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  <head>
    <title>dispcal</title>
    <meta http-equiv="content-type" content="text/html;
      charset=windows-1252">
    <meta name="author" content="Graeme Gill">
  </head>
  <body>
    <h2><b>spectro/dispcal</b></h2>
    <h3>Summary</h3>
    Given calibration target information [white point, maximum
    brightness, and response curve ("gamma")], display a series of test
    patches on the display, and using the colorimetric values read,
    create a calibration lookup tables that make the display meet the
    desired target. The type of instrument is determined by the
    communication port selected. Emission and display measurement
    instruments are supported.<br>
    <h3>Usage</h3>
    <font size="-1"><span style="font-family: monospace;">dispcal
        [-options]</span><i style="font-family: monospace;"> inoutfile</i><br
        style="font-family: monospace;">
      <span style="font-family: monospace;">&nbsp;</span><a
        style="font-family: monospace;" href="#v">-v [n]</a><span
        style="font-family: monospace;">
        &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;



















































        Verbose mode<br>
      </span></font><font size="-1"><span style="font-family:
        monospace;">&nbsp;</span><a style="font-family: monospace;"
        href="#display">-display displayname</a><span
        style="font-family: monospace;"> [X11 only] Choose X11 display
        name<br>
      </span></font><font size="-1"><span style="font-family:
        monospace;">&nbsp;<a href="#dnm">-d n[,m]</a>
        &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
        [X11 only]Choose the display from the following list (default
        1),<br>
        &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
and
optionally
choose
a
different
display
m
for



















































        VideoLUT access.</span></font><br>
    <font size="-1"><span style="font-family: monospace;">&nbsp;<a
          href="#d">-d n</a>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
Choose
the
display
from
the
following
list
(default



















































        1)</span></font><br>
    <span style="font-family: monospace;">&nbsp;<a href="#dweb">-dweb[:port]</a>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;


















































      Display via a web server at port (default 8080)</span><br>
    <span style="font-family: monospace;">&nbsp;<a href="#dmadvr">-dmadvr</a>
      &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;


































      [MSWin] Display via MadVR Video Renderer</span><br>
    <tt>&nbsp;</tt><tt><a href="#dcc">-dcc[:n]</a>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;














    </tt><tt>Display via n'th ChromeCast (default 1, ? for list)</tt><br
      style="font-family: monospace;">
    <font size="-1"><span style="font-family: monospace;"></span><span
        style="font-family: monospace;"></span><span style="font-family:
        monospace;"></span>&nbsp; <span style="font-family: monospace;"></span></font><small
      style="font-family: monospace;"><span style="font-family:
        monospace;"></span><a style="font-family: monospace;" href="#c">-c



















































        listno</a><span style="font-family: monospace;"> &nbsp; &nbsp;
        &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Choose instrument from the
        following list (default 1)<br>
      </span></small><font size="-1"><span style="font-family:
        monospace;">&nbsp;</span><a style="font-family: monospace;"
        href="#r">-r</a><span style="font-family: monospace;">
        &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
        &nbsp;&nbsp;&nbsp;&nbsp; Report on the calibrated display then
        exit</span></font><font size="-1"><span style="font-family:
        monospace;"></span><span style="font-family: monospace;"></span><span
        style="font-family: monospace;"></span><span style="font-family:
        monospace;"><br>
      </span></font><font size="-1"><span style="font-family:
        monospace;">&nbsp;</span><a style="font-family: monospace;"
        href="#R">-R</a><span style="font-family: monospace;">
        &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
        &nbsp;&nbsp;&nbsp;&nbsp; Report on the uncalibrated display then
        exit</span></font><font size="-1"><span style="font-family:
        monospace;"></span></font><br>
    <font size="-1"><span style="font-family: monospace;">&nbsp;</span><a
        style="font-family: monospace;" href="#m">-m</a><span
        style="font-family: monospace;">
        &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
        &nbsp;&nbsp;&nbsp;&nbsp; </span></font><font size="-1"><span
        style="font-family: monospace;">Skip</span><span
        style="font-family: monospace;"> adjustment of the monitor
        controls</span></font><br>
    &nbsp; <font size="-1"><span style="font-family: monospace;"><a
          href="#o">-o [profile.icm]</a>&nbsp;&nbsp;&nbsp;&nbsp; Create
        fast matrix/shaper profile [different filename to outfile.icm]<br>
        &nbsp;<a href="#O">-O description</a>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;



















































        Fast ICC Profile Description string (Default "outfile")<br>
        &nbsp;<a href="#u">-u</a>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
Update
previous
calibration
and
(if
-o
used)
ICC



















































        profile VideoLUTs</span><span style="font-family: monospace;"></span><span
        style="font-family: monospace;"></span><br style="font-family:
        monospace;">
      <span style="font-family: monospace;">&nbsp;</span><a
        style="font-family: monospace;" href="#q">-q [lmh]</a><span
        style="font-family: monospace;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;



















































        Quality - Low, Medium (def), High<br>
        &nbsp;<a href="#p">-p</a>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;








































        Use telephoto mode (ie. for a projector) (if available)<br>
        &nbsp;</span></font><font size="-1"><span style="font-family:
        monospace;"><a href="#y">-y X</a>
        &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;



















































        Display type - instrument specific list to choose from.</span></font><font
      size="-1"><span style="font-family: monospace;"><br
          style="font-family: monospace;">
      </span><span style="font-family: monospace;">&nbsp;</span><a
        style="font-family: monospace;" href="#t">-t [temp]</a><span
        style="font-family: monospace;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
White
Daylight
locus
target,
optional
target
temperaturee
in



















































        deg. K (deflt.)<br>
      </span></font><font size="-1"><span style="font-family:
        monospace;">&nbsp;</span><a style="font-family: monospace;"
        href="#T">-T [temp]</a><span style="font-family: monospace;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
White
Black
Body
locus
target,
optional
target
temperaturee



















































        in deg. K</span></font><br style="font-family: monospace;">
    <font size="-1"><span style="font-family: monospace;"></span><span
        style="font-family: monospace;">&nbsp;</span><a
        style="font-family: monospace;" href="#w">-w x,y</a><span
        style="font-family: monospace;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;



















































        Set the target white point as chromaticity coordinates</span><br
        style="font-family: monospace;">
      <span style="font-family: monospace;">&nbsp;</span><a
        style="font-family: monospace;" href="#b">-b bright</a><span
        style="font-family: monospace;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;



















































        Set the target white brightness in cd/m^2</span><br
        style="font-family: monospace;">
      <span style="font-family: monospace;">&nbsp;</span><a
        style="font-family: monospace;" href="#g">-g gamma</a><span
        style="font-family: monospace;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;



















































        Set the target response curve gamma (Def. 2.4)</span><br
        style="font-family: monospace;">
      <span style="font-family: monospace;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;



















































        Use "-gl" for L*a*b* curve</span><br style="font-family:
        monospace;">
      <span style="font-family: monospace;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;



















































        &nbsp; &nbsp;&nbsp;&nbsp;&nbsp; Use "-gs" for sRGB curve<br>
        &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
Use
"-g709"
for
REC
709
curve
(should
use



















































        -a as well!)<br>
        &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;



















































        Use "-g240" for SMPTE 240M curve </span></font><font size="-1"><span
        style="font-family: monospace;">(should use -a as well!)</span></font><br>
    <font size="-1"><span style="font-family: monospace;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;



















































        Use "-G2.4 -f0" for BT.1886</span></font>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;












































    <br>
    <font size="-1"><span style="font-family: monospace;">&nbsp;</span><a
        style="font-family: monospace;" href="#G">-G gamma</a><span
        style="font-family: monospace;">
        &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
        Set the target response curve actual technical gamma<br>
        &nbsp;<a href="#f">-f [degree]</a>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
Amount
of
black
level
accounted
for
with
output



















































        offset (default all output offset)<br>
        &nbsp;<a href="#a">-a ambient</a>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;



















































        Use viewing condition adjustment for ambient in Lux<br>
      </span></font><font size="-1"><span style="font-family:
        monospace;">&nbsp;<a href="#k">-k factor</a>
        &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
        Amount to try and correct black point hue. Default 1.0, LCD
        default 0.0<br>
      </span></font><font size="-1"><span style="font-family:
        monospace;">&nbsp;<a href="#A">-A rate</a>
        &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
        Rate of blending from neutral to black point. Default 4.0<br>
        &nbsp;<a href="#bhack">-b</a>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;












        Use forced black point hack<br>
      </span></font> <font size="-1"><span style="font-family:
        monospace;">&nbsp;</span><a style="font-family: monospace;"
        href="#B">-B bkbright</a><span style="font-family: monospace;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;



















































        Set the target black brightness in cd/m^2</span></font><br
      style="font-family: monospace;">
    <font size="-1"><span style="font-family: monospace;"></span><span
        style="font-family: monospace;">&nbsp;</span><a
        style="font-family: monospace;" href="#e">-e [n]</a><span
        style="font-family: monospace;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;



















































        Run n verify passes on final curves<br>
      </span></font><font size="-1"><span style="font-family:
        monospace;">&nbsp;</span><a style="font-family: monospace;"
        href="#z">-<font size="-1">z</font></a><span style="font-family:
        monospace;">
        &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;



















































        Run only verify pass on installed calibration curves</span></font><br
      style="font-family: monospace;">
    <font size="-1"><span style="font-family: monospace;"></span><span
        style="font-family: monospace;">&nbsp;<a href="#P">-P
          ho,vo,ss[,vs]</a>&nbsp;&nbsp;&nbsp;&nbsp; Position test window
        and scale it</span><br style="font-family: monospace;">
      <span style="font-family: monospace;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
ho,vi:
0.0
=
left/top,
0.5
=
center,
1.0



















































        = right/bottom etc.</span><br style="font-family: monospace;">
      <span style="font-family: monospace;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
ss:
0.5
=
half,
1.0
=
normal,
2.0



















































        = double etc.<br>
      </span></font><font size="-1"><span style="font-family:
        monospace;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;






































        ss,vs: = optional horizontal, vertical scale.</span></font><br>
    <font size="-1"><span style="font-family: monospace;"> &nbsp;<a
          href="#F">-F</a>
        &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;



















































        Fill whole screen with black background</span></font><font
      size="-1"><span style="font-family: monospace;"></span></font><br>
    <font size="-1"><span style="font-family: monospace;">&nbsp;</span></font><font
      size="-1"><span style="font-family: monospace;"><a href="#E">-E</a>
        &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;






























      </span></font><small><span style="font-family: monospace;">Video
        encode output as (16-235)/255 "TV" levels</span></small><br
      style="font-family: monospace;">
    <font size="-1"><span style="font-family: monospace;"></span><span
        style="font-family: monospace;">&nbsp;</span><a
        style="font-family: monospace;" href="#n">-n</a><span
        style="font-family: monospace;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
&nbsp;&nbsp;&nbsp;&nbsp;
[X11
only]
Don't
set
override
redirect
on



















































        test window<br>
      </span></font><font size="-1"><span style="font-family:
        monospace;">&nbsp;</span><a style="font-family: monospace;"
        href="#J">-J</a><span style="font-family: monospace;">
        &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
        &nbsp;&nbsp;&nbsp;&nbsp; Run instrument calibration first<br>
      </span></font><font size="-1"><span style="font-family:
        monospace;">&nbsp;<a href="#N">-N</a>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;



















































        Disable initial calibration of instrument if possible</span></font><br>
    <font size="-1"><span style="font-family: monospace;">&nbsp;</span><a
        style="font-family: monospace;" href="#H">-H</a><span
        style="font-family: monospace;">
        &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
        &nbsp;&nbsp;&nbsp;&nbsp; Use high resolution spectrum mode (if
        available)<br>
      </span></font><font size="-1"><span style="font-family:
        monospace;"></span><span style="font-family: monospace;"><br>
        &nbsp;</span></font><font size="-1"><span style="font-family:
        monospace;"><span style="text-decoration: underline;"></span><a
          href="#X1">-X file.ccmx</a>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;



















































        Apply Colorimeter Correction Matrix</span></font><br>
    <span style="font-family: monospace;">&nbsp;<a href="#X2">-X
        file.ccss</a>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
Use
Colorimeter
Calibration



















































      Spectral Samples for calibration</span><font size="-1"><span
        style="font-family: monospace;"><br>
      </span></font><small><span style="font-family: monospace;">&nbsp;</span><a
        style="font-family: monospace;" href="#Q">-Q <i>observ</i></a><span
        style="font-family: monospace;">&nbsp; &nbsp; &nbsp; &nbsp;
        &nbsp;&nbsp;&nbsp; Choose CIE Observer for spectrometer or CCSS
        colorimeter data:</span><br style="font-family: monospace;">
      <span style="font-family: monospace;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;



















































        &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 1931_2 </span></small><small><span
        style="font-family: monospace;">(def.)</span></small><small><span
        style="font-family: monospace;">, 1964_10, </span></small><small><span
        style="font-family: monospace;"><tt><small>2012_2, 2012_10, </small></tt>S&amp;B


        1955_2, shaw, J&amp;V 1978_2, 1964_10c or file.cmf<br>
        &nbsp;<a href="#I">-I b|w</a>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;



















































        Drift compensation, Black: -Ib, White: -Iw, Both: -Ibw</span></small><br>
    <small><span style="font-family: monospace;"><tt>&nbsp;<a href="#YR">-Y




















            R:<i>rate</i></a>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;




















          Override measured refresh rate with rate Hz<br>
        </tt>&nbsp;</span></small><font size="-1"><span
        style="font-family: monospace;"></span><a style=" font-family:
        monospace;" href="#YA">-<font size="-1">Y</font> A</a><span
        style="font-family: monospace;">
        &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
        &nbsp;&nbsp;&nbsp; Use non-adaptive integration time mode (if
        available).</span></font><br>
    <font size="-1"><span style="font-family: monospace;">&nbsp;</span><a
        style=" font-family: monospace;" href="#Yp">-<font size="-1">Y</font>
        <font size="-1">p</font></a><span style="font-family:
        monospace;">
        &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
        &nbsp;&nbsp;&nbsp; Don't wait for the instrument to be placed on
        the display</span></font><br>
    <small><span style="font-family: monospace;"> </span></small><font
      size="-1"><span style="font-family: monospace;">&nbsp;</span><a
        style="font-family: monospace;" href="#C">-C "command"</a><span
        style="font-family: monospace;">
        &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Invoke shell
        "command" each time a color is set</span></font><br>
    <font size="-1"><span style="font-family: monospace;">&nbsp;</span><a
        style="font-family: monospace;" href="#M">-M "command"</a><span
        style="font-family: monospace;">
        &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Invoke shell
        "command" each time a color is measured</span></font><font
      size="-1"><span style="font-family: monospace;"></span><span
        style="font-family: monospace;"></span></font><br>
    <font size="-1"><span style="font-family: monospace;">&nbsp;<a
          href="#W">-W n|h|x</a>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
Override
serial
port
flow
control:
n
=
none,



















































        h = HW, x = Xon/Xoff</span></font><font size="-1"><span
        style="font-family: monospace;"></span></font><br>
    <font size="-1"><span style="font-family: monospace;"> </span></font><font
      size="-1"><span style="font-family: monospace;">&nbsp;</span><a
        style="font-family: monospace;" href="#D">-D [level]</a><span
        style="font-family: monospace;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;



















































        Print debug diagnostics to stderr</span></font><br
      style="font-family: monospace;">
    <font size="-1"><span style="font-family: monospace;"></span><span
        style="font-family: monospace;">&nbsp;</span><a
        style="font-family: monospace;" href="#p1"><i>inoutfile</i></a><span
        style="font-family: monospace;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;



















































      </span><span style="font-family: monospace;">Base name for created
        or updated </span></font><font size="-1"><a style="font-family:
        monospace;" href="cal_format.html">.cal</a><span
        style="font-family: monospace;"></span></font><font size="-1"><span
        style="font-family: monospace;">&nbsp; and <a
          href="File_Formats.html#ICC">.icm</a> output files</span></font><br>
    <br>
    <h3>Comments<br>
    </h3>
    This is the tool is used for adjusting and calibrating a display to
    reach specified target behaviour, and optionally profiling it.&nbsp;
    For best results on a CRT, you should run this against a neutral
    grey desktop background, and avoid having any bright images or
    windows on the screen at the time you run dispcal. You could also
    use the <span style="font-weight: bold;">-B</span> option to black
    the whole screen out, although this will make it impossible to
    control dispcal unless you have more than one display.<br>
    <br>
    <a name="v"></a> The <b>-v</b> flag reports progress information,
    as well as other statistics about the progress of calibration. A
    numerical argument greater than 1 gives greater verbosity. 2 will
    give per step adjustment and repeat information, while 3 will give
    even greater technical detail.<br>
    <br>
    <a name="display"></a>When running on a UNIX based system that used
    the X11 Windowing System, <b>dispcal</b> will by default use the
    $DISPLAY environment variable to determine which local or remote
    display and screen to read from. This can be overridden by supplying
    an X11 display name to the <span style="font-weight: bold;">-display</span>
    option. Note that if Xinerama is active, you can't select the screen
    using $DISPLAY or -display, you have to select it using the <span
      style="font-weight: bold;">-d</span> parameter.<br>
    <br>
    <a name="d"></a> By default the main display will be the location of
    the test window. If the system has more than one display or screen,
    an alternate display/screen can be selected with the <span
      style="font-weight: bold;">-d</span> parameter. If you invoke <span
      style="font-weight: bold;">dispcal</span> so as to display the
    usage information (i.e. "dispcal -?" or "dispcal --"), then the
    discovered displays/screens will be listed. Multiple displays may
    not be listed, if they appear as a single display to the operating
    system (ie. the multi-display support is hidden in the video card
    driver). On UNIX based system that used the X11 Windowing System,
    the <span style="font-weight: bold;">-d</span> parameter will
    override the screen specified by the $DISPLAY or parameter.<br>
    <br>
    <span style="font-weight: bold;">Note</span> that if VideoLUTs for a
    display are not accessible (i.e. no hardware calibration
    capability), <span style="font-weight: bold;">dispcal</span> will
    will issue a warning, but continue creating a calibration based on
    the display "as-is" rather than its native response. See the <a
      href="dispcal.html#o">-o</a> flag for an explanation of the
    implications of having no access to the VideoLUTs.<br>
    <br>
    On X11 the inability to access VideoLUTs could be because you are
    trying to access a remote display, and the remote display doesn't
    support the XF86VidMode extension, or perhaps you are running
    multiple monitors using NVidia TwinView, or MergedFB, and trying to
    access anything other than the primary monitor. TwinView and
    MergedFB don't properly support the XF86VidMode extension for
    multiple displays. You can use <a href="dispwin.html#r">dispwin -r</a>
    to test whether the VideoLUTs are accessible for a particular
    display. See also below, on how to select a different display for
    VideoLUT access. Also note that dispcal will fail if the Visual
    depth doesn't match the VideoLUT depth. Typically the VideoLUTs have
    256 entries per color component, so the Visual generally needs to be
    24 bits, 8 bits per color component.<br>
    <br>
    <a name="dnm"></a>Because of the difficulty cause by TwinView and
    MergedFB in X11 based systems, you can optionally specify a separate
    display number after the display that is going to be used to present
    test patches, for accessing the VideoLUT hardware. This must be
    specified as a single string, e.g. <span style="font-weight: bold;">-d



















































      1,2</span> . Some experimentation may be needed using <a
      href="dispwin.html">dispwin</a> on such systems, to discover what
    screen has access to the VideoLUT hardware, and which screens the
    test patches appear on. You may be able to calibrate one screen, and
    then share the calibration with another screen. Profiling can be
    done independently to calibration on each screen.<br>
    <br>
    <a name="dweb"></a><span style="font-weight: bold;">-dweb</span> or
    <span style="font-weight: bold;">-dweb:port</span> starts a
    standalone web server on your machine, which then allows a local or
    remote web browser to display the the color test patches. By default
    port <span style="font-weight: bold;">8080</span> is used, but this
    can be overridden by appending a <span style="font-weight: bold;">:</span>
    and the port number i.e. <span style="font-weight: bold;">-dweb:8001</span>.
    The URL will be <span style="font-weight: bold;">http://</span>
    then name of the machine or its I.P. address followed by a colon and
    the port number - e.g something like <span style="font-weight:
      bold;">http://192.168.0.1:8080</span>. If you use the verbose
    option (<span style="font-weight: bold;">-v</span>) then a likely
    URL will be printed once the server is started, or you could run <span
      style="font-weight: bold;">ipconfig</span> (MSWin) or <span
      style="font-weight: bold;">/sbin/ifconfig</span> (Linux or OS X)
    and identify an internet address for your machine that way. <b>JavaScript</b>
    needs to be enabled in your web browser for this to work. You may
    have to modify any firewall to permit port 8080 to be accessed on
    your machine.<br>
    <br>
    Note that if you use this method of displaying test patches, that
    there is no access to the display VideoLUTs and that the colors will
    be displayed with 8 bit per component precision, and any
    screen-saver or power-saver will not be disabled. You will also be
    at the mercy of any color management applied by the web browser, and
    may have to carefully review and configure such color management.
    See the <a href="#o">-o</a> flag for an explanation of the
    implications of having no access to the VideoLUTs.<br>
    <br>
    <a name="dmadvr"></a><span style="font-weight: bold;">-dmadvr</span>
    [MSWin only] causes test patches to be displayed using the MadVR
    video renderer. Note that will have to start <b>MadTPG</b> before
    running dispcal, and that while you can adjust the "Test Pattern
    Configuration" controls, you should <u>not</u> normally alter the
    "Existing Calibration" controls, as dispcal will set these
    appropriately. <br>
    <br>
    <a name="dcc"></a><span style="font-weight: bold;">-dcc</span> or <b>-dcc:<i>no</i></b>
    causes test patches to be displayed using and available <a
      href="http://en.wikipedia.org/wiki/Chromecast">ChromeCast</a> to
    your TV. Use <b>-dcc:?</b> to display a list of ChromeCasts on your
    local network. Note that the ChromeCast as a test patch source is
    probably the<b> least accurate</b> of your choices, since it
    up-samples the test patch and transforms from RGB to YCC and back,
    but should be accurate within  1 bit. You may have to modify any
    firewall to permit port 8081 to be accessed on your machine if it
    falls back to the Default receiver (see <a href="Installing.html">installation







      instructions</a> for your platform).<br>
    <br>
    <a name="c"></a> <span style="font-weight: bold;">-c</span> The
    instrument is assumed to communicate through a USB or serial
    communication port, and the port can be selected with the <b>-c</b>
    option, if the instrument is not connected to the first port. If you
    invoke <span style="font-weight: bold;">dispcal</span> so as to
    display the usage information (i.e. "dispcal -?" or "dispcal --"),
    then the discovered USB and serial ports will be listed. On
    UNIX/Linux, a list of all possible serial ports are shown, but not
    all of them may actually be present on your system.<br>
    <br>
    <a name="r"></a> The -<span style="font-weight: bold;">r</span> and
    <span style="font-weight: bold;"><a name="R"></a>-R </span>flags
    perform a quick measurement of current display behaviour, reports
    and then exits. If the <span style="font-weight: bold;">-r</span>
    flag is used the measurement are taken using the currently loaded
    calibration (Video LUT) curves, and in the case of MadVR renderer
    test patch display the Color Management 3dLut. If <span
      style="font-weight: bold;">-R</span> is use, then the uncalibrated
    ("raw" or "native") behaviour is measured (ie. no VideoLut or CM).
    Reported are: <br>
    <br>
    &nbsp;&nbsp;&nbsp; Black Brightness in cd/m^2<br>
    &nbsp;&nbsp;&nbsp; White Brightness in cd/m^2<br>
    &nbsp;&nbsp;&nbsp; The approximate Gamma<br>
    &nbsp;&nbsp;&nbsp; The white point x,y chromaticity co-ordinates<br>
    &nbsp;&nbsp;&nbsp; The correlated color temperature in Kelvin, and
    the CIEDE200 to the Black Body locus.<br>
    &nbsp;&nbsp;&nbsp; The correlated Daylight temperature in Kelvin,
    and the CIEDE200 to the Daylight locus.<br>
    &nbsp;&nbsp;&nbsp; The visual color temperature in Kelvin, and the
    CIEDE200 to the Black Body locus.<br>
    &nbsp;&nbsp;&nbsp; The visual Daylight temperature in Kelvin, and
    the CIEDE200 to the Daylight locus.<br>
    &nbsp;&nbsp;&nbsp; The visual color temperature in Kelvin<br>
    (for <span style="font-weight: bold;">-R </span>"raw":)<br>
    &nbsp;&nbsp;&nbsp; The apparent VideoLUT entry number of significant
    bits.<br>
    <br>
    Note that the correlated color temperature is the temperature of a
    black body radiator that has the closest color to the white point
    measured using the traditional CIE 1960 UCS space color difference
    formula. The correlated daylight temperature is a similar thing,
    except the CIE daylight locus is used. The visual color temperature
    values are calculated similarly to the correlated color
    temperatures, but using the modern CIEDE2000 color difference
    formula to calculate a better visual approximation to the closest
    temperature to the displays white point. There will be no difference
    between the UCS and CIEDE2000 temperatures if the display white
    point actually lies on the particular locus.<br>
    <br>
    <a name="m"></a> The -<span style="font-weight: bold;">m</span>
    option skips the usual process of adjusting the display monitor
    contrast, brightness and white point controls, and skips straight to
    calibration.<br>
    <br>
    <a name="o"></a><span style="font-weight: bold;">-o [</span><span
      style="font-style: italic;">profile.icm</span><span
      style="font-weight: bold;">]</span> Normally <span
      style="font-weight: bold;">dispcal</span> creates just a
    calibration file, which can then be used for subsequent
    characterization using <a href="dispread.html">dispread</a> and
    profiling using <a href="colprof.html">colprof</a>. If the <span
      style="font-weight: bold;">-o</span> flag is used, <span
      style="font-weight: bold;">dispcal</span> will also create a
    shaper/matrix profile. By default it will create a profile named <span
      style="font-weight: bold;">inoutfile.icm</span>, but a differently
    named file can be created or updated by specifying the name after
    the <span style="font-weight: bold;">-o</span> flag. If the <span
      style="font-weight: bold;">-u</span> flag is used with <span
      style="font-weight: bold;">-o</span>, then the ICC profile <span
      style="font-weight: bold;">vcgt</span> calibration curves will be
    updated.<br>
    <br>
    Note that if VideoLUT access is not possible for the display, that
    hardware calibration is not possible. dispcal will create
    calibration curves anyway with a warning, and if a profile is
    created, it will not contain a 'vcgt' tag, but instead will have the
    calibration curves incorporated into the profile itself. If
    calibration parameters are chosen that change the displays white
    point or brightness, then this will result in a slightly unusual
    profile that has a white point that does not correspond with
    R=G=B=1.0. Some systems may not cope properly with this type of
    profile. See the <a href="Scenarios.html#PM7">tutorial</a> for a
    further explanation.<br>
    <br>
    <a name="O"></a>The <b>-O</b> parameter allows setting of the
    shaper/matrix profile description tag. The parameter should be a
    string that describes the device and profile. With most command line
    shells, it will be necessary to enclose the parameter with double
    quotes, so that spaces and other special characters are included in
    the parameter, and not mistaken for the start of another flag, or as
    a final command line parameter. Many programs that deal with ICC
    profiles use the description tag to identify a profile, rather than
    the profile filename, so using a descriptive string is important in
    being able to find a profile. By default, the profile file name will
    be used as the description.<br>
    <br>
    <a name="u"></a><span style="font-weight: bold;">-u</span> Normally
    <span style="font-weight: bold;">dispcal</span> creates a new
    calibration file and optional profile, based on the requested
    targets and the response of the display. This can take a fair amount
    of time, particularly if a high quality level has been selected, so
    to speed up the process of keeping a display in calibration the <span
      style="font-weight: bold;">-u</span> flag can be used. This uses
    the same calibration targets as the previous calibration but does a
    smaller number of refinement passes, enough to improve the accuracy
    of the calibration to account for drift in the device. If the <span
      style="font-weight: bold;">-o</span> flag is used as well, then
    the ICC profile <span style="font-weight: bold;"></span>will have
    its vcgt tag updated with the new calibration. This keeps the
    profile up to date with the display. Normally <span
      style="font-weight: bold;">dispcal -u</span> will use the same
    quality level that was specified in the previous calibration, but
    this can be overridden using the <span style="font-weight: bold;">-q</span>
    flag. Any options that attempt to change the calibration target (ie.
    white point, brightness, gamma etc.) will be ignored. Adjustment of
    the display monitor controls is skipped. A profile cannot be updated
    if the display does not support hardware calibration (no VideoLUT
    access).<br>
    <br>
    <a name="q"></a>&nbsp; Quality - Low, Medium (def), High. The <span
      style="font-weight: bold;">-q</span> flag determines how much time
    and effort to go to in calibrating the display. The higher the
    quality, the more test readings will be done, the more refinement
    passes will be done, the tighter will be the accuracy tolerance, and
    the more detailed will be the calibration of the display. The result
    will ultimately be limited by the accuracy of the instrument, the
    repeatability of the display and instrument, and the resolution of
    the Video Lookup table entries and Digital or Analogue output
    (RAMDAC).<br>
    <br>
    <a name="p"></a>The <span style="font-weight: bold;">-p</span> flag
    allows measuring in telephoto mode, using instruments that support
    this mode, e.g. the ColorMunki. Telephoto mode is one for taking
    emissive measurements from a distance (ie. telespectometer,
    tele-colorimeter) mode, and typically would be used for measuring
    projector type displays. If a device does not support a specific
    telephoto mode, then the normal emissive mode may be suitable for
    measuring projectors.<br>
    <br>
    <a name="y"></a>&nbsp; The <span style="font-weight: bold;">-y</span>
    flag allows setting the Display Type. The selection typically
    determines two aspects of of the instrument operation: <span
      style="font-weight: bold;">1)</span> It may set the measuring mode
    to suite <a
      href="http://en.wikipedia.org/wiki/Comparison_of_display_technology"><span
        style="font-weight: bold;">refresh</span> or <span
        style="font-weight: bold;">non-refresh</span> displays</a>.
    Typically only LCD (Liquid Crystal) displays have a non-refresh
    nature. <span style="font-weight: bold;">2)</span> It may select an
    instrument calibration matrix suitable for a particular display
    type. The selections available depends on the type and model of
    instrument, and a list of the options for the discovered instruments
    will be shown in the <a href="ArgyllDoc.html#CmdLine">usage</a>
    information. For more details on what particular instruments support
    and how this works, see <a href="instruments.html">Operation of
      particular instruments</a>. <b>3)</b> Any installed CCSS files
    (if applicable), or CCMX files. These files are typically created
    using <a href="ccxxmake.html">ccxxmake</a>, and installed using <a
      href="oeminst.html">oeminst</a>. The default and Base Calibration
    types will be indicated in the usage.<br>
    <br>
    <a name="t"></a><span style="text-decoration: underline;"></span> <span
      style="font-weight: bold;">-t</span> Set the target white point
    locus to the equivalent of a Daylight spectrum of the given
    temperature in degrees Kelvin. By default the white point target
    will be the native white of the display, and it's color temperature
    and delta E to the daylight spectrum locus will be shown during
    monitor adjustment, and adjustments will be recommended to put the
    display white point directly on the Daylight locus. If a Daylight
    color temperature is given as an argument to <span
      style="font-weight: bold;">-t</span>, then this will become the
    target of the adjustment, and the recommended adjustments will be
    those needed to make the monitor white point meet the target.
    Typical&nbsp; values might be 5000 for matching printed output, or
    6500, which gives a brighter, bluer look. A white point temperature
    different to that native to the display may limit the maximum
    brightness possible.<br>
    <br>
    <a name="T"></a><span style="text-decoration: underline;"></span> <span
      style="font-weight: bold;">-T</span>&nbsp; Same functionality as
    the <span style="font-weight: bold;">-t</span> option, except the
    white point locus will be the Black Body, or Planckian locus, rather
    than the Daylight locus. While these two white point loci are quite
    close, they are subtly different. If a temperature is given as an
    argument, this will become the Black Body target temperature during
    adjustment.<br>
    <br>
    <a name="w"></a><span style="font-weight: bold;">-w</span>&nbsp; An
    alternative to specifying a&nbsp; white point target in Daylight or
    Black Body degrees Kevin, is to specify it in chromaticity
    co-ordinates. This allows the white point to be a color other than
    one on the Daylight or Black Body. Note that the x,y numbers must be
    specified as a single string (no space between the numbers and the
    comma).<br>
    <br>
    <a name="b"></a><span style="font-weight: bold;">-b</span>&nbsp; Set
    the target brightness of white in cd/m^2. If this number cannot be
    reached, the brightest output possible is chosen, consistent with
    matching the white point target. Note that many of the instruments
    are not particularly accurate when assessing the absolute display
    brightness in cd/m^2. <span style="font-weight: bold;">NOTE</span>
    that some LCD screens behave a little strangely near their absolute
    white point, and may therefore exhibit odd behavior at values just
    below white. It may be advisable in such cases to set a brightness
    slightly less than the maximum such a display is capable of.<br>
    <br>
    <a name="g"></a><span style="font-weight: bold;">-g gamma</span>&nbsp;
Set



















































    the target response curve gamma. This is normally an exponential
    curve (output = input ^gamma), and defaults to 2.4 on MSWindows and
    Macintosh OS X 10.6 or latter and Linux/Unix (which is typical of a
    CRT type displays real response), and 1.8 on a Macintosh (prior to
    OS X 10.6). Four pre-defined curves can be used as well: the sRGB
    colorspace response curve, which is an exponent curve with a
    straight segment at the dark end and an overall response of
    approximately gamma 2.2 (<span style="font-weight: bold;">-gs</span>),
the



















































    L* curve, which is the response of the CIE L*a*b* perceptual
    colorspace (<span style="font-weight: bold;">-gl</span>). the REC
    709 video standard response curve (<span style="font-weight: bold;">-g709</span>)
    and the SMPTE 240M video standard response curve (<span
      style="font-weight: bold;">-g240</span>) <br>
    <br>
    <span style="font-weight: bold;">Note</span> that a real display
    can't reproduce any of these ideal curves, since it will have a
    non-zero black point, whereas all the ideal curves assume zero light
    at zero input. In the case of a gamma curve target, dispcal uses an
    actual technical power curve shape that aims for the same relative
    output at 50% input as the ideal gamma power curve. To allow for the
    non-zero black level of a real display, by default <span
      style="font-weight: bold;">dispcal</span> will offset the target
    curve values so that zero input gives the actual black level of the
    display (output offset). This ensures that the target curve better
    corresponds to the typical natural behavior of displays, but it may
    not be the most visually even progression from display minimum, but
    this behavior can be changed using the <span style="font-weight:
      bold;">-f</span> option (see below).<br>
    <br>
    <span style="font-weight: bold;">Also note</span> that many color
    spaces are encoded with, and labelled as having a gamma of
    approximately<span style="font-weight: bold;"> 2.2</span> (ie. sRGB,
    REC 709, SMPTE 240M, Macintosh OS X 10.6), but are actually intended
    to be displayed on a display with a typical CRT gamma of <span
      style="font-weight: bold;">2.4</span> viewed in a darkened
    environment. This is because this <span style="font-weight: bold;">2.2</span>
    gamma is a source gamma encoding in bright viewing conditions such
    as a television studio, while typical display viewing conditions are
    quite dark by comparison, and a contrast expansion of (approx.)
    gamma 1.1 is desirable to make the images look as intended. So if
    you are displaying images encoded to the sRGB standard, or
    displaying video through the calibration, just setting the gamma
    curve to sRGB or REC 709 (respectively) is probably <span
      style="font-weight: bold;">not what you want!</span> What you
    probably want to do, is to set the gamma curve to about gamma 2.4,
    so that the contrast range is expanded appropriately, or <span
      style="text-decoration: underline; font-weight: bold;">alternatively</span>
    use sRGB or REC 709 or a gamm of 2.2 but <span style="font-weight:
      bold;">also</span> use the <span style="font-weight: bold;">-a</span>
    parameter to specify the actual ambient viewing conditions, so that
    <span style="font-weight: bold;">dispcal</span> can make an
    appropriate contrast enhancement. If your instrument is capable of
    measuring ambient light levels, then you can do so during the
    interactive display control adjustment. See
    &lt;http://www.color.org/sRGB.xalter&gt; for details of how sRGB is
    intended to be used.<br>
    <br>
    It is hard to know whether Apple Macintosh computers prior to OS X
    10.6 should also have such an adjustment, since it is not really
    possible to know whether colors labelled as being in such a
    colorspace are actually encoded in that gamma with the expectation
    that they will be displayed on a display with that actual response,
    or whether they are intended to be displayed on a display that
    contrast expands by a power 1.1.&nbsp; Both situations might be the
    case, depending on how source material is created!<br>
    <br>
    <a name="G"></a><span style="font-weight: bold;">-G gamma</span>&nbsp;
As



















































    explained above, the gamma value provided to the <span
      style="font-weight: bold;">-g</span> option is used to set and
    actual response curve that makes an allowance for the non-zero black
    of the actual display, and will have the same relative output at 50%
    input as the ideal gamma power curve, and so best matches typical
    expectations. The <span style="font-weight: bold;">-G</span> option
    is an alternative that allows the <span style="font-weight: bold;">actual</span>
    power to be specified instead, meaning that when combined with the
    displays non-zero black value, the response at 50% input will
    probably not match that of the ideal power curve with that gamma
    value.<br>
    <br>
    <a name="f"></a><span style="font-weight: bold;">-f [degree]</span>:
    As explained in for the <span style="font-weight: bold;">-g</span>
    and <span style="font-weight: bold;">-G</span> options, real
    displays do not have a zero black response, while all the target
    response curves do, so this has to be allowed for in some way. The
    default way of handling this (equivalent to -f 1.0)&nbsp; is to
    allow for this at the output of the ideal response curve, by
    offsetting and scaling the output values.<span style="font-weight:
      bold;"></span> This defined a curve that will match the responses
    that many other systems provide and may be a better match to the
    natural response of the display, but will give a less visually even
    response from black<span style="font-weight: bold;"></span>. The
    other alternative is to offset and scale the input values into the
    ideal response curve so that zero input gives the actual non-zero
    display response. This ensures the most visually even progression
    from display minimum, but might be hard to achieve since it is
    different to the naturally response of a display. A subtlety is to
    provide a split between how much of the offset is accounted for as
    input to the ideal response curve, and how much is accounted for at
    the output, and this can be done by providing a parameter <span
      style="font-weight: bold;">-f degree</span>, where the degree is
    0.0 accounts for it all as input offset, and 1.0 accounts for all of
    it as output offset. If <span style="font-weight: bold;">-f</span>
    is used without a specified degree, a degree of 0.0 is assumed, the
    opposite of the default. <span style="font-weight: bold;">Note</span>
    that using all input offset (degree == 0.0) is equivalent to the use
    of the <span style="font-weight: bold;">BT.1886</span> transfer
    function.<br>
    <br>
    <a name="a"></a><span style="font-weight: bold;">-a ambient</span>:
    As explained for the <span style="font-weight: bold;">-g</span>
    parameter, often colors are encoded in a situation with viewing
    conditions that are quite different to the viewing conditions of a
    typical display, with the expectation that this difference in
    viewing conditions will be allowed for in the way the display is
    calibrated. The <span style="font-weight: bold;">-a</span> option
    is a way of doing this. By default <span style="font-weight: bold;">dispcal</span>
    will not make any allowances for viewing conditions, but will
    calibrate to the specified response curve, but if the <span
      style="font-weight: bold;">-a</span> option is used, or the
    ambient level is measured during the interactive display controls
    portion of the calibration, an appropriate viewing conditions
    adjustment will be performed. For a gamma value or sRGB, the
    original viewing conditions will be assumed to be that of the sRGB
    standard viewing conditions, while for REC 709 and SMPTE 240M they
    will be assumed to be television studio viewing conditions. By
    specifying or measuring the ambient lighting for your display, a
    viewing conditions adjustment based on the CIECAM02 color appearance
    model will be made for the brightness of&nbsp; your display and the
    contrast it makes with your ambient light levels. <br>
    <br>
    <a name="k"></a><span style="font-weight: bold;">-k factor</span>:
    Normally this will be set automatically, based on the measured black
    level of the display. A <span style="font-weight: bold;">-k</span>
    factor of 1.0 will make all colors down the neutral axis (R=G=B)
    have the same hue as the chosen white point. Near the black point,
    red, green or blue can only be added, not subtracted from zero, so
    the process of making the near black colors have the desired hue,
    will <span style="font-weight: bold;">lighten</span> them to some
    extent. For a device with a good contrast ratio or a black point
    that has nearly the same hue as the white, this should not affect
    the contrast ratio too severely. If the device contrast ratio is not
    so good, and the native black hue is noticeably different to that of
    the chosen white point (which is often the case for <span
      style="font-weight: bold;">LCD</span> type displays, or <span
      style="font-weight: bold;">CRT</span> type displays with one
    channel which has a poor level of black), this could have a
    noticeably detrimental effect on an already limited contrast ratio,
    and result in a black that is not as good as it can be, and a lower
    <span style="font-weight: bold;">-k</span> factor should be used. <span
      style="font-weight: bold;">-k</span> values can range between 0.0
    (no correction of black) to 1.0 (full correction of black). If less
    than full correction is chosen, then the resulting calibration
    curves will have the target white point down most of the curve, but
    will then blend over to the native or compromise black point that is
    blacker, but not of the right hue. The rate of this blend can be
    controlled with the <span style="font-weight: bold;">-A</span>
    parameter (see below). For applications where maximum contrast ratio
    is important (such as <b>Video</b>), use <b>-k0</b>. <br>
    <br>
    <a name="A"></a><span style="font-weight: bold;">-A rate</span>:&nbsp;
If



















































    the black point is not being set completely to the same hue as the
    white point (ie. because the <span style="font-weight: bold;">-k</span>
    factor is less than 1.0), then the resulting calibration curves will
    have the target white point down most of the curve, but will then
    blend over to the native or compromise black point that is blacker,
    but not of the right hue. The rate of this blend can be controlled
    with the <span style="font-weight: bold;">-A</span> parameter. The
    default value 4.0, which results in a target that switches from the
    white point target to the black, moderately close to the black
    point. While this typically gives a good visual result with the
    target neutral hue being maintained to the point where the crossover
    to the black hue is not visible, it may be asking too much of some
    displays (typically LCD type displays), and there may be some visual
    effects due to inconsistent color with viewing angle. For this
    situation a smaller value may give a better visual result (e.g. try
    values of 3.0 or 2.0. A value of 1.0 will set a pure linear blend
    from white point to black point). If there is too much coloration
    near black, try a larger value, e.g. 6.0 or 8.0.<br>
    <br>
    <a name="bhack"></a>The <b>-b</b> flag forces source 0,0,0 to map
    to destination 0,0,0. This may be useful with displays that have a
    very dark black point, and with an instrument is unable to measure
    it precisely, and where it is known in some other way that the
    display is <u>very well behaved</u> from black (i.e. that it has no
    "dead zone" above zero device input). Using this option with a
    display that is <u>not</u> well behaved, may result in a loss of
    shadow detail. This will override any <b>-k</b> factor.<br>
    <br>
    <a name="B"></a><span style="font-weight: bold;">-B</span>&nbsp; Set
    the target brightness of black in cd/m^2 (i.e. the absolute Y
    value). Setting too high a value may give strange results as it
    interacts with trying to achieve the target "advertised" gamma curve
    shape. You could try using -f 1 if this causes a problem.<br>
    <br>
    <a name="e"></a><span style="font-weight: bold;">-e [n]</span> Run <span
      style="font-weight: bold;">n</span> verify passes on the final
    curves. This is an extra set of instrument readings, that can be
    used to estimate how well the device will match the targets with the
    computed calibration curves. Note that the usefulness of the
    verification is sometimes limited by the repeatability of the device
    &amp; instrument readings. This is often evident for CRT displays,
    which (due to their refresh rate) flicker. More than one
    verification pass can be done by providing the parameter <span
      style="font-weight: bold;">n</span>, and by then comparing the
    successive verifications, some idea of the repeatability can be
    ascertained. The verification uses a fixed number of semi-random
    test values to test the calibration.<br>
    <br>
    <a name="z"></a><span style="font-weight: bold;">-z</span> Run
    verify pass on the display as it is currently setup (currently
    installed LUT curves). This will use the usual input parameters to
    establish the expected (target) characteristic. <span
      style="font-weight: bold;">Note</span> that if the initial
    calibration was modified due to it being out of gamut of the
    display, verify will show the resulting discrepancy. You can use <a
      href="dispwin.html">dispwin</a> to load a <span
      style="font-weight: bold;">.cal</span> file into the display
    before running dispcal <span style="font-weight: bold;">-z</span>.
    Note that if you set an Ambient light level interactively during the
    calibration, you need to enter the same number that was measured and
    set using the <span style="font-weight: bold;">-a</span> parameter
    for verify.<br>
    <br>
    <a name="P"></a> The <span style="font-weight: bold;">-P</span>
    parameter allows you to position and size the test patch window. By
    default it is places in the center of the screen, and sized
    appropriately for the type of instrument, or 10% of the width of the
    display if the display size is unknown.. The <span
      style="font-weight: bold;">ho</span> and <span
      style="font-weight: bold;">vo</span> values govern the horizontal
    and vertical offset respectively. A value of 0.0 positions the
    window to the far left or top of the screen, a value of 0.5
    positions it in the center of the screen (the default), and 1.0
    positions it to the far right or bottom of the screen. If three
    parameters are provided, then the <span style="font-weight: bold;">ss</span>
    parameter is a scale factor for the test window size. A value of 0.5
    for instance, would produce a half sized window. A value of 2.0 will
    produce a double size window. If four parameters are provided, then
    the last two set independent horizontal and vertical scaling
    factors. Note that the ho,vo,ss or ho,vo,hs,vs numbers must be
    specified as a single string (no space between the numbers and the
    comma). For example, to create a double sized test window at the top
    right of the screen, use <span style="font-weight: bold;">-P 1,0,2</span>
    . To create a window twice as wide as high: <span
      style="font-weight: bold;">-P 1,0,2,1</span>.<br>
    <br>
    <a name="F"></a> The <span style="font-weight: bold;">-F</span>
    flag causes the while screen behind the test window to be masked
    with black. This can aid black accuracy when measuring CRT displays
    or projectors.<br>
    <br>
    <a name="E"></a> The <span style="font-weight: bold;">-E</span>
    flag causes the display test values to be scaled to the Video RGB
    encoding range of (16-235)/255. This also modifies the resulting
    calibration curve behavior downstream of dispcal. If a calibration
    curve created using -E gets installed or converted to an ICC profile
    'vcgt' tag in the process of creating a profile in dispcal or
    colprof, the incoming full range values will first have the
    calibration curve applied and then be scaled to the Video encoding
    range (16-235)/255.<br>
    <br>
    <a name="n"></a><span style="font-weight: bold;">-n</span> When
    running on a UNIX based system that used the X11 Windowing System, <b>dispcal</b>
    normally selects the override redirect so that the test window will
    appear above any other windows on the display. On some systems this
    can interfere with window manager operation, and the <b>-n</b>
    option turns this behaviour off.<br>
    <br>
    <a name="J"></a> The -<span style="font-weight: bold;">J</span>
    option runs through the black and sensor relative calibration
    routines for the Xrite DTP92 and DTP94 instruments, the black level
    calibration for the Eye-One Display 1, and a CRT frequency
    calibration for the Eye-One Display 2. For the black calibration the
    instrument should be placed on an opaque, black surface, and any
    stray light should be avoided by placing something opaque over the
    instrument. If a Spectrolino is being used, then a white and black
    calibration will always be performed before the instrument can be
    placed on the display, unless the <a href="dispcal.html#N">-N</a>
    flag is used. Generally it is not necessary to do a calibration
    every time an instrument is used, just now and again. There is also
    no point in doing&nbsp; a CRT frequency calibration, as this will be
    done automatically at the commencement of patch reading, and will be
    lost between runs.<br>
    <br>
    <a name="N"></a> <span style="font-weight: bold;">-N</span> Any
    instrument that requires regular calibration will ask for
    calibration on initial start-up. Sometimes this can be awkward if
    the instrument is being mounted in some sort of measuring jig, or
    annoying if several sets of readings are being taken in quick
    succession. The -<span style="font-weight: bold;">N</span>
    suppresses this initial calibration if a valid and not timed out
    previous calibration is recorded in the instrument or on the host
    computer. It is advisable to only use this option on the second and
    subsequent measurements in a single session.<br>
    <br>
    <a name="H"></a> The -<span style="font-weight: bold;">H</span>
    option turns on high resolution spectral mode, if the instrument
    supports it, such as the Eye-One Pro. See <a
      href="instruments.html">Operation of particular instruments</a>
    for more details. This may give better accuracy for display
    measurements.<br>
    <br>
    <a name="X1"></a> The -<span style="font-weight: bold;">X <span
        style="font-style: italic;">file.ccmx</span></span> option reads
    a <a href="File_Formats.html#.ccmx">Colorimeter Correction Matrix</a>
    from the given file, and applies it to the colorimeter instruments
    readings. This can improve a colorimeters accuracy for a particular
    type of display. A list of contributed <span style="font-weight:
      bold;">ccmx</span> files is <a href="ccmxs.html">here</a>.<br>
    <br>
    <a name="X2"></a> The -<span style="font-weight: bold;">X <span
        style="font-style: italic;">file.ccss</span></span> option reads
    a <a href="File_Formats.html#.ccss">Colorimeter Calibration
      Spectral Sample</a> from the given file, and uses it to set the
    colorimeter instruments calibration. This will only work with
    colorimeters that rely on sensor spectral sensitivity calibration
    information (ie. the X-Rite <span style="font-weight: bold;">i1d3</span>,
    or the DataColor <span style="font-weight: bold;">Spyder4 &amp;
      Spyder 5</span>).This can improve a colorimeters accuracy for a
    particular type of display. A list of contributed <span
      style="font-weight: bold;">ccss</span> files is <a
      href="ccsss.html">here</a>.<br>
    <br>
    <a name="Q"></a> The <b>-Q</b> flag allows specifying a tristimulus
    observer, and is used to compute PCS (Profile Connection Space)
    tristimulus values from spectral readings or using a colorimeter
    that has CCSS capability. The following choices are available:<br>
    <b>&nbsp; 1931_2</b> selects the standard CIE 1931 2 degree
    observer. The default.<br>
    &nbsp; <b>1964_10</b> selects the standard CIE 1964 10 degree
    observer<br>
    <b>&nbsp; 2012_2</b> selects the proposed CIE 2012 2 degree observer<br>
    &nbsp; <b>2012_10</b> selects the proposed CIE 2012 10 degree
    observer<br>
    &nbsp; <b>1955_2</b> selects the Stiles and Birch 1955 2 degree
    observer<br>
    &nbsp; <b>1978_2 </b>selects the Judd and Voss 1978 2 degree
    observer<br>
    &nbsp; <b>shaw</b> selects the Shaw and Fairchild 1997 2 degree
    observer<br>
    &nbsp; <b>1964_10c</b> selects a version of the CIE 1964 10 degree
    observer that has been adjusted using a 3x3 matrix to better agree
    with the 1931 2 degree observer.<br>
    &nbsp; <i><b>file.cmf</b></i> selects an observer specified by the
    given <a href="File_Formats.html#.cmf">.cmf</a> file.<br>
    <br>
    <span style="font-weight: bold;">NOTE</span> that if you select
    anything other than the default 1931 2 degree observer, that the Y
    values will not be cd/m^2, due to the Y curve not being the CIE 1924
    photopic V(&#955;) luminosity function.<br>
    <br>
    <a name="I"></a> The -<span style="font-weight: bold;">I <span
        style="font-style: italic;">b|w</span></span> options invoke
    instrument black level, and display white level compensation
    (respectively). Instrument black level drift compensation attempts
    to combat instrument black calibration drift by using a display
    black test patch as a reference. If an instrument is not
    acclimatised sufficiently to the measurement conditions, changes in
    temperature can affect the black readings. Display white level drift
    compensation attempts to combat changes in display brightness as it
    warms up by measuring a white patch every so often, and using it to
    normalise all the other readings. If just instrument black drift
    compensation is needed, use <span style="font-weight: bold;">-Ib</span>.
    If just display white level compensation is needed, use <span
      style="font-weight: bold;">-Iw</span>. If both are needed, use <span
      style="font-weight: bold;">-Ibw</span> or <span
      style="font-weight: bold;">-Iwb</span>.<span style="font-weight:
      bold;"> </span><br>
    <br>
    <a name="YR"></a> The -<span style="font-weight: bold;">Y R:<i>rate</i></span>
    options overrides calibration of the instrument refresh rate. This
    may be useful if the instrument supports this function and the
    refresh rate cannot be accurately calibrated from the display
    itself.<br>
    <br>
    <a name="YA"></a> The -<span style="font-weight: bold;">Y A</span>
    option uses a non-adaptive integration time emission measurement
    mode, if the instrument supports it, such as the Eye-One Pro,
    ColorMunki, i1d3 and K10. By default an adaptive integration time
    measurement mode will be used for emission measurements, but some
    instruments support a fixed integration time mode that can be used
    with display devices. This may give faster measurement times, but
    may also give less accurate low level readings.<br>
    <br>
    <a name="Yp"></a> The -<span style="font-weight: bold;">Y p</span>
    option skips asking the user to place the instrument on the display.
    Normally a grey patch is displayed, and then the user is asked to
    confirm that the instrument is in place, so that readings can
    commence. This flag disables that check. This may be useful in
    automating certain operations.<br>
    <br>
    <a name="C"></a> The -<span style="font-weight: bold;">C</span> <span
      style="font-weight: bold;">"command" </span>option allows a
    method of relaying each test value to some other display than that
    on the system running dispcal (for instance, a photo frame, PDA
    screen etc.), by causing the given command to be invoked to the
    shell, with six arguments. The first three arguments are the RGB
    test color as integers in the range 0 to 255, the second three
    parameters are the RGB test color as floating point numbers in the
    range 0.0 to 1.0. The script or tool should relay the given color to
    the screen in some manner (e.g. by generating a raster file of the
    given color and sending it to the display being profiled), before
    returning. Note that a test window will also be created on the
    system running dispread.<br>
    <br>
    <a name="M"></a> The -<span style="font-weight: bold;">M</span> <span
      style="font-weight: bold;">"command" </span>option allows a
    method of gathering each test value from some external source, such
    as an instrument that is not directly supported by Argyll. The given
    command is involked to the shell, with six arguments. The first
    three arguments are the RGB test color as integers in the range 0 to
    255, the second three parameters are the RGB test color as floating
    point numbers in the range 0.0 to 1.0. The script or tool should
    create a file called <span style="font-weight: bold;">"command.meas</span>"
    that contains the XYZ values for the given RGB (or measured from the
    test window) in cd/m^2 as three numbers separated by spaces, before
    returning. If the command returns a non-zero return value, dispcal
    will abort. Note that a test window will also be created on the
    system running dispcal.<br>
    <br>
    <a name="W"></a>The <b>-W</b> <span style="font-weight: bold;">n|h|x</span>
    parameter overrides the default serial communications flow control
    setting. The value <span style="font-weight: bold;">n</span> turns
    all flow control off, <span style="font-weight: bold;">h</span>
    sets hardware handshaking, and <span style="font-weight: bold;">x</span>
    sets Xon/Xoff handshaking. This commend may be useful in workaround
    serial communications issues with some systems and cables. <br>
    <br>
    <a name="D"></a>The <b>-D</b> flag causes communications and other
    instrument diagnostics to be printed to stdout. A level can be set
    between 1 .. 9, that may give progressively more verbose
    information, depending on the instrument. This can be useful in
    tracking down why an instrument can't connect.<br>
    <br>
    <a name="p1"></a><span style="font-weight: bold;">inoutfile</span>
    The final parameter on the command line is the base filename for the
    <a href="cal_format.html">.cal</a> file and the optional ICC
    profile. Normally this will be created (or an existing file will be
    overwritten). If the <span style="font-weight: bold;">-u</span>
    flag is used, then these files will be updated. If a different ICC
    profile name needs to be specified, do so as an argument to the <span
      style="font-weight: bold;">-o</span> flag.<br>
    <br>
    <span style="font-weight: bold;">NOTE</span> that on an X11 system,
    if the environment variable <span style="font-weight: bold;">ARGYLL_IGNORE_XRANDR1_2</span>
    is set (ie. set it to "yes"), then the presence of the XRandR 1.2
    extension will be ignored, and other extensions such as Xinerama and
    XF86VidMode extension will be used. This may be a way to work around
    buggy XRandR 1.2 implementations.<br>
    <br>
    <hr style="width: 100%; height: 2px;">
    <h2><a name="Adjustment"></a>Discussion and guide to display control
      adjustment:</h2>
    <br>
    The adjustment of the display controls (brightness, contrast, R, G
    &amp; B channel controls etc.) is very dependent on the particular
    monitor. Different types and brands of monitors will have different
    controls, or controls that operate in different ways. Some displays
    have almost no user controls, and so you may well be best skipping
    display adjustment, and going straight to calibration.<br>
    <br>
    Almost all LCD displays lack a real <span style="font-weight:
      bold;">contrast</span> control. Those that do present such a
    control generally fake it by adjusting the video signal. For this
    reason it is usually best to set an LCD's <span style="font-weight:
      bold;">contrast</span> control at its neutral setting (ie. the
    setting at which it doesn't change the video signal). Unfortunately,
    it can be hard to know what this neutral setting is. On some
    displays it is 50%, others 75%. If the LCD display has a "reset to
    factory defaults" mode, then try using this first, as a way of
    setting the <span style="font-weight: bold;">contrast</span>
    control to neutral. The LCD <span style="font-weight: bold;">brightness</span>
    control generally adjusts the level of backlighting the display
    gets, which affects the maximum brightness, and also tends to raise
    or lower the black level in proportion, without changing the
    displays response curve shape or overall contrast ratio. If your LCD
    display has a <span style="font-weight: bold;">backlight</span>
    control as well as a <span style="font-weight: bold;">brightness</span>
    control, then the brightness control is also probably being faked,
    and you are probably better off setting it to it's neutral setting,
    and using the <span style="font-weight: bold;">backlight</span>
    control in place of <span style="font-weight: bold;">brightness</span>
    in the following adjustments.<br>
    <br>
    Some high end displays have the ability to mimic various standard
    colorspaces such as sRGB or AdobeRGB. You could choose to calibrate
    and profile the display in such an emulation mode, although you
    probably don't want to fight the emulations white point and gamma.
    To get the best out of such a display you really want to choose it's
    "Native Gamut" setting, whatever that is called. Note that some
    people have reported bad experiences in trying to use "6-axis custom
    controls" on displays such as the Dell U2410, so attempting to use
    such a mode should be approached with caution. Ideally such a mode
    should be used to give just the underlying native display response,
    but the settings to achieve this may be very difficult to determine,
    and/or it may not be possible, depending on how such a mode distorts
    the RGB signals.<br>
    <br>
    On CRT based displays, the <span style="font-weight: bold;">brightness</span>
    control generally adjusts the black level of the display (sometimes
    called the <span style="font-weight: bold;">offset</span>), and as
    a side effect, tends to change the maximum brightness too. A CRT <span
      style="font-weight: bold;">contrast</span> control generally
    adjusts the maximum brightness (sometimes called <span
      style="font-weight: bold;">gain</span>) without affecting the
    black level a great deal. On a CRT both the <span
      style="font-weight: bold;">brightness</span> and <span
      style="font-weight: bold;">contrast</span> controls will tend to
    affect the shape or gamma of the display response curve.<br>
    <br>
    Many displays have some sort of color temperature adjustment. This
    may be in the form of some pre-set color temperatures, or in the
    form of individual Red, Green and Blue channel gain adjustments.
    Some CRT displays also have R, G &amp; B channel offset adjustments
    that will affect the color temperatures near black, as well as
    affect the individual channels curve shape. The color temperature
    adjustment will generally affect the maximum brightness, and may
    also affect the black level and the shape of the display response
    curves.<br>
    <br>
    Some special (expensive) LCD displays may have a white point
    adjustment that changes the color of the backlight. If you do not
    have one of these types of LCD displays, then attempting to change
    the white point of the display (even if it appears to have a "<span
      style="font-weight: bold;">white point selection</span>" or <span
      style="font-weight: bold;">R/G/B</span> "<span style="font-weight:
      bold;">gain</span>" controls") may not be a good idea, as once
    again these controls are probably being faked by manipulating the
    signal levels. Even if you do manage to change the white point
    significantly, it may do things like change the mid tone color too
    dramatically, or create a display response that is hard to correct
    with calibration, or results in side effects such as quantization
    (banding) or other undesirable effects. You may have to try out
    various controls (and your aim points for the display calibration),
    to decide what is reasonable to attempt on an LCD display.<br>
    <br>
    Due to the variety of controls as well as the interaction between
    them, it can be an iterative process to arrive at a good monitor
    set-up, before proceeding on to calibrating and profiling a display.
    For this reason, <span style="font-weight: bold;">dispcal</span>
    offers a menu of adjustment modes, so that the user can
    interactively and iteratively adjust the display controls to meet
    the desired targets.<br>
    <br>
    &nbsp; 1) Black level (CRT: Brightness)<br>
    &nbsp; 2) White point (Color temperature, R,G,B, Gain/Contrast)<br>
    &nbsp; 3) White level (CRT: Gain/Contrast, LCD:
    Brightness/Backlight)<br>
    &nbsp; 4) Black point (R,G,B, Offset/Brightness)<br>
    &nbsp; 5) Check all<br>
    &nbsp; 6) Measure and set ambient for viewing condition adjustment<br>
    &nbsp; 7) Continue on to calibration<br>
    &nbsp; 8) Exit<br>
    <br>
    There are four basic adjustment modes. Normally one would proceed
    through them in the order above, then perhaps repeat the first
    adjustment, before checking the overall settings. The White point
    and White level modes operate slightly differently, depending on
    whether a white target point has been set using the <span
      style="font-weight: bold;">-t -T</span> or <span
      style="font-weight: bold;">-w</span> options, and on whether a
    brightness target has been set using the <span style="font-weight:
      bold;">-b</span> option.<br>
    <br>
    <br>
    The first mode lets you adjust the black level of a CRT display.
    Given the current white level, it calculates a value that should
    produce a 1% display brightness if the black level is set correctly.
    After doing some initial measurements, it will show the target
    brightness value (in cd/m^2) on one line, and then underneath it
    will show continuously updated readings from the display. The left
    most character will switch from '\' to '/' or back again each time a
    reading is updated. Some instruments can be quite slow in measuring
    dark colors, and it's best to wait for a reading update before
    changing the controls more than once. Underneath the target value is
    displayed the current reading, and to the right of this is a '+',
    '-' or '=' symbol, which gives a hint as to which way to adjust the
    brightness control to improve the match to the target.<br>
    <br>
    <small style="font-weight: bold;"><span style="font-family:
        monospace;">&nbsp; Adjust CRT brightness to get target level.
        Press space when done.</span><br style="font-family: monospace;">
      <span style="font-family: monospace;">&nbsp;&nbsp; &nbsp; Target
        0.60</span><br style="font-family: monospace;">
      <span style="font-family: monospace;">&nbsp; / Current 0.68&nbsp;
        -</span></small><br>
    <br>
    Once happy with the adjustment, press space to go back to the menu.<br>
    <br>
    <br>
    The second mode lets you adjust the color of the white point of the
    display. If a target white point has been set, it will show the
    target brightness value (in cd/m^2) on one line, together with the
    target chromaticity co-ordinates for the white point, and then
    underneath it will show continuously updated readings from the
    display. The left most character will switch from '\' to '/' or back
    again each time a reading is updated. Underneath the target
    brightness value is displayed the current reading, and then the
    current chromaticity co-ordinate values. To the right of this is the
    current delta E of the white point from the target, and further to
    the right are hints '+', '-' or '='&nbsp; as to which direction to
    adjust the individual Red, Green and Blue gain settings to move the
    white point in the direction of the target, and reduce the delta E.
    If the symbol is doubled, then this channel will have the greatest
    effect. If you do not have individual channel gain controls, then
    try choosing amongst color temperature pre-sets, to find one with
    the lowest delta E. Depending on the stability of the display, the
    coarseness of the controls, and the repeatability of the instrument,
    you may not be able to get a perfectly zero delta E.<br>
    <br>
    &nbsp;&nbsp; <small style="font-weight: bold;"><span
        style="font-family: monospace;">Adjust R,G &amp; B gain to get
        target x,y. Press space when done.<br>
        &nbsp;&nbsp; &nbsp; Target B 60.00, x 0.3451, y 0.3516<br>
        &nbsp; / Current B 60.05, x 0.3426, y 0.3506&nbsp; DE&nbsp;
        1.4&nbsp; R+&nbsp; G+&nbsp; B--</span><span style="font-family:
        monospace;"></span></small><br>
    <br>
    If you did not set a white point target, then the information shown
    is a little different - it will show the initial white point value,
    as well as the color temperature, and the CIEDE2000 of the white
    point to either the Daylight or Black Body locus (depending on
    whether the <span style="font-weight: bold;">-T</span> flag was
    set). The constantly updated values show the same thing, and the
    Red, Green and Blue control hints show the direction to adjust the
    controls to place the white point on the locus. The control that
    will have the most direct effect on the color temperature will be
    the Blue, while the Green will most directly move the white point
    towards or away from the locus, thereby reducing the delta E of the
    white point to the locus (but there is interaction).<br>
    <br>
    <small style="font-weight: bold;"><span style="font-family:
        monospace;">Adjust R,G &amp; B gain to desired white point.
        Press space when done.</span><br style="font-family: monospace;">
      <span style="font-family: monospace;">&nbsp; Initial B 47.25, x
        0.3417, y 0.3456, CDT 5113 DE&nbsp; 6.9</span><br
        style="font-family: monospace;">
      <span style="font-family: monospace;">\ Current B 47.38, x 0.3420,
        y 0.3460&nbsp; CDT 5104 DE&nbsp; 6.7&nbsp; R-- G+&nbsp; B-</span></small><br>
    <br>
    &nbsp;The brightness value is just there as a guide to what effect
    the adjustment is having on the overall brightness. Usually the
    white level brightness is adjusted using the next adjustment mode.
    Once happy with the adjustment, press space to go back to the menu.<br>
    <br>
    <br>
    The third mode lets you adjust the brightness of white on the
    display. If you set a target brightness using the <span
      style="font-weight: bold;"><span style="font-weight: bold;">-b</span></span>
    parameter, it will show the target brightness value (in cd/m^2) on
    one line, and then underneath it will show continuously updated
    readings from the display. The left most character will switch from
    '\' to '/' or back again each time a reading is updated. Underneath
    the target value is displayed the current reading, and to the right
    of this is a '+', '-' or '=' symbol, which gives a hint as to which
    way to adjust the CRT contrast or LCD brightness control to improve
    the match to the target.<br>
    <br>
    &nbsp;&nbsp; <small style="font-weight: bold;"><span
        style="font-family: monospace;">Adjust CRT Contrast or LCD
        Brightness to get target level. Press space when done.<br>
        &nbsp;&nbsp; &nbsp; Target 60.00<br>
        &nbsp; / Current 59.96&nbsp; +</span><span style="font-family:
        monospace;"></span></small><br>
    <br>
    If you did not set a brightness target, it will show the initial
    brightness as the target, and the current brightness, which you can
    then set any way you want:<br>
    <br>
    <small style="font-weight: bold;"><span style="font-family:
        monospace;">Adjust CRT Contrast or LCD Brightness to desired
        level. Press space when done.</span><br style="font-family:
        monospace;">
      <span style="font-family: monospace;">&nbsp; Initial 47.32</span><br
        style="font-family: monospace;">
      <span style="font-family: monospace;">/ Current 47.54</span></small><br>
    <br>
    Once happy with the adjustment, press space to go back to the menu.<br>
    <br>
    <br>
    The fourth mode lets you adjust the color of the black point of the
    display, if the display has Red, Green and Blue channel offset
    controls. It will show the target 1% brightness value (in cd/m^2) on
    one line, together with the target chromaticity co-ordinates for the
    black point, and then underneath it will show continuously updated
    readings from the display. The left most character will switch from
    '\' to '/' or back again each time a reading is updated. Underneath
    the target brightness value is displayed the current reading, and
    then the current chromaticity co-ordinate values. To the right of
    this is the current delta E of the black point from the target, and
    further to the right are hints '+', '-' or '='&nbsp; as to which
    direction to adjust the individual Red, Green and Blue offset
    settings to move the black point in the right direction. If the
    symbol is doubled, then this channel will have the greatest effect.
    <br>
    <br>
    <span style="font-family: monospace;"><span style="font-weight:
        bold;">&nbsp; Adjust R,G &amp; B offsets to get target x,y.
        Press space when done.<br>
        &nbsp;&nbsp; &nbsp; Target B 0.60, x 0.3451, y 0.3516<br>
        &nbsp; \ Current B 0.62, x 0.2782, y 0.2331&nbsp; DE&nbsp;
        10.3&nbsp; R+&nbsp; G++ B-</span></span><small
      style="font-weight: bold;"><span style="font-family: monospace;"></span><span
        style="font-family: monospace;"></span></small><br>
    <br>
    The 1%&nbsp; brightness value is just there as a guide to what
    effect the adjustment is having on the 1% brightness level. The
    combined channel offsets may have an effect on this in combination
    with the CRT brightness control. Press space to go back to the menu.<br>
    <br>
    <br>
    The fifth selection checks on the overall settings.&nbsp; If targets
    have been set, it will be like:<br>
    <br>
    <small style="font-weight: bold;"><span style="font-family:
        monospace;">&nbsp; Target Brightness = 50.00, Current = 47.44,
        error = -5.1%<br>
        &nbsp; Target 50% Level&nbsp; = 10.32, Current =&nbsp; 8.10,
        error = -4.4%<br>
        &nbsp; Target Near Black =&nbsp; 0.47, Current =&nbsp; 0.68,
        error =&nbsp; 0.4%<br>
        &nbsp; Target white = x 0.3458, y 0.3586, Current = x 0.3420, y
        0.3454, error =&nbsp; 7.55 DE<br>
        &nbsp; Target black = x 0.3458, y 0.3586, Current = x 0.2908, y
        0.2270, error = 29.69 DE</span><span style="font-family:
        monospace;"></span></small><br>
    <br>
    or if no targets are set:<br>
    <br>
    <small style="font-weight: bold;"><span style="font-family:
        monospace;">&nbsp; Current Brightness = 46.28</span><br
        style="font-family: monospace;">
      <span style="font-family: monospace;">&nbsp; Target 50%
        Level&nbsp; = 10.07, Current =&nbsp; 7.52, error = -5.5%</span><br
        style="font-family: monospace;">
      <span style="font-family: monospace;">&nbsp; Target Near Black
        =&nbsp; 0.46, Current =&nbsp; 0.46, error = -0.0%</span><br
        style="font-family: monospace;">
      <span style="font-family: monospace;">&nbsp; Current white = x
        0.3439, y 0.3466, VCT 5098K DE&nbsp; 3.0</span><br
        style="font-family: monospace;">
      <span style="font-family: monospace;">&nbsp; Target black = x
        0.3439, y 0.3466, Current = x 0.3093, y 0.2165, error = 30.30 DE</span></small><br>
    <br>
    and will then go back to the menu.<br>
    <br>
    The sixth selection <span style="font-weight: bold;">6)</span>
    allows the reading of you ambient lighting conditions if your
    instrument supports such a mode. Doing so will enable the <span
      style="font-weight: bold;">-a</span> option to compensate for your
    viewing conditions in the subsequent calibration. See <a
      href="dispcal.html#a">-a</a>.<br>
    <br>
    Once&nbsp; you're happy with the display set-up, you can either
    proceed on to the rest of the calibration by selecting <span
      style="font-weight: bold;">7)</span>, or exit and re-start by
    selecting <span style="font-weight: bold;">8)</span>. You might
    want to re-start if you want to change the calibration targets.<br>
    <br>
    <hr style="width: 100%; height: 2px;">
    <h2>Other caveats:</h2>
    NOTE that some <span style="font-weight: bold;">LCD</span> screens
    behave a little strangely near their absolute white point, and may
    therefore exhibit odd behavior at values just below white. It may be
    advisable in such cases to set a brightness slightly less than the
    maximum such a display is capable of.<br>
    <br>
    The program attempts to stop any screensaver or powersaver from
    interfering with the measurements, but this may not be effective on
    some systems, so it may be necessary to manually disable the
    screensaver and/or powersaver before commencing the calibration with
    a large number of patches.<br>
    <br>
    The calibration tables produced maintain the maximum level of
    precision available on a system. If the display has VideoLUTs
    available (Video Lookup Tables that the frame buffer values pass
    through on their way to the display) and thier outputs are better
    than 8 bits per component, then the resulting curves can reflect
    this, although few current operating systems and/or display cards
    actually support better than 8 bit per component output.<br>
    <br>
    If calibration curves are created for a display in which VideoLUTs
    are not available, then the resulting calibration file will be
    marked to indicate this, and a subsequent profile created with the
    calibration will not have the calibration converted to the 'vcgt'
    tag, since such a tag can't be loaded into the displays VideoLUTs.<br>
    <br>
    If communications break down with a USB connected instrument, you
    may have to unplug it, and plug it in again to recover operation.<br>
    <br>
    Some systems (Apple OS X in particular) have a special set of user
    interface controls ("Universal Access") that allows altering the
    display in ways designed to assist visually impaired users, by
    increasing contrast etc. This will interfere badly with any attempts
    to calibrate or profile such a system, and must be turned off in
    order to do so. Note that certain magic keyboard sequences can turn
    this on by accident.<br>
    <br>
    <br>
    <br>
    <br>
    <br>
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