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<h3>Jhead is a command line driven program for manipulating the non-image parts of Exif flavour
JPEG files that most digital cameras produce.</h3><p>

Windows / Mac users:  Jhead has <b>no Graphical User Interface</b>.  Clicking on it with the mouse from Windows 
or Mac OS-X won't do anything for you - you have to <b>use it from the Command prompt</b> 


<h3>Jhead v2.97 program Features</h3>
<ul>
<li>Extracting camera settings from Exif image files
<li>Able to set and/or adjust the Exif time field
<li>Manipulation (extract, replace, regenerate) of Exif integral thumbnails
<li>Transplant Exif image header from one JPEG to another
<li>Edit JPEG comment fields
<li>Automatically rotate images upright (using jpegtran) according to "orientation" tag.
<li>Manage running programs on large batches of Jpegs and restoring Exif header
    information afterwards.
<li>Display embedded GPS info (if present)
</ul>


<h3>General metadata options</h3>
<table cellpadding=5>

<tr valign=top><td><b>-te &lt;name&gt;
  <td>
    Transplant Exif header from image &lt;name&gt; into specified image.  This option is
    useful if you like to edit the photos but still want the Exif header on your photos.
    As most photo editing programs will wipe out the Exif header, this option can be used
    to re-transplant them back in after editing the photos.
    <br>
    This feature has an interesting 'relative path' option for specifying the thumbnail name.
    Whenever the &lt;name&gt; contains the characters '&i', jhead will substitute the original
    filename for this name.  This allows creating a 'relative name' when doing a whole
    batch of files.  For example, the incantation:
    <ul>jhead -te "originals\&i" *.jpg</ul>
    would transfer the Exif header for each .jpg file in the originals directory by the same name,
    Both Win32 and most UNIX shells treat the '&' character in a special way, so you have to
    put quotes around that command line option for the '&' to even be passed to the program.


<tr valign=top><td><b>-dc
<td>Delete comment field from the JPEG header.  Note that the comment
    is not part of the Exif header.

<tr valign=top><td><b>-de
<td>Delete the Exif header entirely.  This leaves other sections (IPTC, XMP, comment) intact

<tr valign=top><td><b>-di
<td>Delete IPTC section (if present).  Leaves other sections intact.

<tr valign=top><td><b>-dx
<td>Delete XMP section (if present).  Leaves other sections intact.

<tr valign=top><td><b>-du
<td>Delete any sections that jhead doesn't know about.  Leaves Exif, XMP, IPTC and comment
    sections intact.

<tr valign=top><td><b>-purejpg
<td>Delete all JPEG sections that aren't necessary for rendering the image.  Strips any
    metadata that various applications may have left in the image.  A combination of 
    the -de -dc and -du options.

<tr valign=top><td><b>-mkexif
<td>Creates minimal Exif header.  Exif header contains date/time, and empty thumbnail
    fields only.  Date/time set to file time by default.
    use with -rgt option if you want the Exif header to contain a thumbnail.
    Note that Exif header creation is very limited at this time, and no other fields
    can be added to the Exif header this way.

<tr valign=top><td><b>-ce
<td>Edit the JPEG header comment field (note, this comment field is outside the Exif structure
    and can be part of Exif and non Exif style JPEG images).
    <br>
    A temporary file containing the comment is created and a text editor is launched to edit
    the file.  The editor is specified in the EDITOR environment variable.  If none is specified
    notepad or vi are used under Windows and UNIX respectively.  After the editor exits,
    the data is transferred back into the image, and the temporary file deleted.

<tr valign=top><td><b>-cs &lt;name&gt;
<td>Save comment section to a file

<tr valign=top><td><b>-ci &lt;name&gt;
<td>Replace comment with text from file.

<tr valign=top><td><b>-cl&nbsp&lt;comment&gt;
<td>Replace comment with comment from command line.
</table>


<h3>Date / Time manipulation options</h3>
<table cellpadding=5>

<tr valign=top><td><b>-ft
<td>Sets the file's system time stamp to what is stored in the Exif header.

<tr valign=top><td><b>-dsft
<td>Sets the Exif timestamp to the file's timestamp.  Requires an Exif header to pre-exist.
    Use -mkexif option to create one if needed.

<tr valign=top><td><b>-n[&lt;fmt-string&gt;]
<td>This option causes files to be renamed and/or moved according to the Exif header "DateTimeOriginal" field.
    If the file is not an Exif file, or the DateTimeOriginal does not contain a valid value, 
    the file date is used.
    <p>
    If the name includes '/' or '\' (under windows), this is interpreted as a new path for
    the file.  If the new path does not exist, the path will be created.
    <p>
    If the [fmt-string] is omitted, the file will be renamed to MMDD-HHMMSS.
    <br>
    If a [fmt-string] is provided, the fmt-string will be passed to the 
    strftime function for formatting.  In addition, if the format string contains '%f', this will
    substitute the original name of the file (minus extension).
    <br>
    A sequence number may also be included by including '%i' in the format string.  Leading
    zeros can be specified.  '%03i' for example will pad the numbers to '001', '002'...
    this works just like printf in C, but with '%i' instead of '%d'.
    <br>
    If the target name already exists, the name will be appended with "a", "b", "c", etc,
    unless the name ends with a letter, in which case it will be appended with "0", "1", "2", etc.
    <br>
    This feature is especially useful if more than one digital camera was used to take pictures
    of an event.  By renaming them to a scheme according to date, they will automatically
    appear in order of taking when viewed with some sort of viewer like Xnview or AcdSee, and
    sorted by name.  Or you could use the -ft option and view the images sorted by date.
    Typically, one of the carera's date will be set not quite right, in which case you may have
    to use the -ta or -da options on those files first.
    <p>
    <b>Some of the more useful arguments for strftime are:</b>

    <table>
    <tr><td>%d &nbsp </td><td>Day of month as decimal number (01  31)
    <tr><td>%H</td><td>Hour in 24-hour format (00  23)
    <tr><td>%j</td><td>Day of year as decimal number (001  366)
    <tr><td>%m</td><td>Month as decimal number (01  12)
    <tr><td>%M</td><td>Minute as decimal number (00  59)
    <tr><td>%S</td><td>Second as decimal number (00  59)
    <tr><td>%U</td><td>Week of year as decimal number, with Sunday as first day of week (00  53)
    <tr><td>%w</td><td>Weekday as decimal number (0  6; Sunday is 0)
    <tr><td>%y</td><td>Year without century, as decimal number (00  99)
    <tr><td>%Y</td><td>Year with century, as decimal number
    </table>
    <p>
    Example:<br>
    &nbsp &nbsp jhead -n%Y%m%d-%H%M%S *.jpg<p>
    This will rename files matched by *.jpg according to YYYYMMDD-HHMMSS
    <p>
    Note to Windows batch file users:  '%' is used to deliminate macros in Windows batch files.  You must
    use %% to get one % passed to the program.  So from a batch file, you would have to write "jhead -n%%Y%%m%%d-%%H%%M%%S *.jpg"
    <p>
    For a full listing of strftime arguments, look up the strftime function.  Note that some arguments
    to the strftime function (not listed here) produce strings with characters such as '/' and ':' that
    may not be valid as part of a filename on various systems.

<tr valign=top><td><b>-a
<td>(Windows only option).  Rename files with the same name but different extension as well.
    This is useful for renaming .AVI files based on Exif file in .THM, or to rename sound annotation
    files or raw files with jpeg files.  Use together with '-n' option.

<tr valign=top><td><b>-ta&lt;timediff&gt;
<td>Adjust time stored in the Exif header by h:mm forwards or backwards.  Useful when having
    taken pictures with the wrong time set on the camera, such as after travelling across
    time zones, or when daylight savings time has changed.
    This option uses the time from the "DateTimeOriginal" (tag 0x9003) field, but sets
    all the time fields in the Exif header to the new value.
    <p>
    Examples:<br>
    Adjust time one hour forward (you would use this after you forgot to set daylight savings 
    time on the digicam)<br>
    <ul>jhead -ta+1:00 *.jpg</ul>
    Adjust time back by 23 seconds (you would use this to get the timestamps from two digicams
    in sync after you found that they didn't quite align)
    <ul>jhead -ta-0:00:23 *.jpg</ul>
    Adjust time forward by 2 days and 1 hour (49 hours)
    <ul>jhead -ta+49 *.jpg</ul>

<tr valign=top><td><b>-da&lt;date&gt;-&lt;date&gt;
<td>Works like -ta, but for specifying large date offsets, to be used when fixing dates from 
    cameras where the date was set incorrectly, such as having date and time reset by battery
    removal on some cameras.  This feature is best for adjusting dates on pictures taken
    over a large range of dates.  For pictures all taken the same date, the "-ds" option
    is often easier to use.
    <p>
    Because different months and years have different numbers of days in them, a simple offset
    for months, days, years would lead to unexpected results at times.  The time offset is
    thus specified as a difference between two dates, so that jhead can figure out exactly
    how many days the timestamp needs to be adjusted by, including leap years and daylight
    savings time changes.
    The dates are specified as yyyy:mm:dd.  For sub-day adjustments, a time of day can also
    be included, by specifying yyyy:nn:dd/hh:mm or yyyy:mm:dd/hh:mm:ss
    <p>
    Examples:<br>
    Year on camera was set to 2004 instead of 2005 for pictures taken in April
    <ul>jhead -da2005:03:01-2004:03:01</ul>
    Default camera date is 2002:01:01, and date was reset on 2005:05:29 at 11:21 am
    <ul>jhead -da2005:05:29/11:21-2002:01:01</ul>

<tr valign=top><td><b>-ts&lt;date-time&gt;
<td>Sets the date and time stored in the Exif header to what is specified on the command line.
    This option changes all the date fields in the Exif header.
    Time must be specified as:<br>
    <font face=courier> &nbsp &nbsp yyyy:mm:dd-hh:mm:ss</font><p>

<tr valign=top><td><b>-ds&lt;date-time&gt;
<td>Sets the date stored in the Exif header to what is specified on the command line.
    Can be used to set date, just year and month, or just year.
    Date is specified as:<br>
    <font face=courier> &nbsp &nbsp yyyy:mm:dd,  yyyy:mm, or yyyy</font><p>

</table>
<h3>Thumbnail manipulation options</h3>
<table cellpadding=5>
<tr valign=top><td><b>-dt
<td>Delete thumbnails from the Exif header, but leave the
    interesting parts intact.  This option truncates the thumbnail from the Exif header, provided
    that the thumbnail is the last part of the Exif header (which so far as I know is always the case).
    Exif headers have a built-in thumbnail, which is typically 240x160 and 10k in size.
    This thumbnail is used by digital cameras.  Windows XP, as well
    as various photo viewing software may also use this thumbnail if present, but work just fine
    if it isn't.

<tr valign=top><td><b>-st &lt;name&gt;
<td>Save the built in thumbnail from Jpegs that came from a digital camera.  The thumbnail lives
    inside the Exif header, and is a very low-res JPEG image.  Note that making
    any changes to a photo, except for with some programs, generally wipes out the Exif header
    and with it the thumbnail.
    <br>
    I implemented this option because I kept getting asked about having such an option.
    I don't consider the
    built in thumbnails to be all that useful - too low res.  However, now you can see for
    yourself.  I always generate my thumbnails using ImageMagick (see end of this page).
    <br>
    Like the '-te' option, this feature has the 'relative path' option for specifying the 
    thumbnail name.
    Whenever the &lt;name&gt; contains the characters '&i', jhead will substitute the original
    filename for this name.  This allows creating a 'relative name' when doing a whole
    batch of files.  For example, the incantation:
    <ul>jhead -st "thumbnails\&i" *.jpg</ul>
    would create a thumbnail for each .jpg file in the thumbnails directory by the same name,
    (provided that the thumbnails directory exists, of course).
    Both Win32 and most UNIX shells treat the '&' character in a special way, so you have to
    put quotes around that command line option for the '&' to even be passed to the program.
    <p>
    If a '-' is specified for the output file, the thumbnail is sent to stdout. (UNIX build only)

<tr valign=top><td><b>-rt &lt;name&gt;
<td>Replace thumbnails from the Exif header.
    This only works if the Exif header already contains an Exif header a thumbnail.

<tr valign=top><td><b>-rgt[size]    
<td>Regnerate Exif thumbnail.
    'size' specifies maximum height or width of thumbnail.
    I added this option because I had a lot of images that I had rotated with various tools that don't
    update the Exif header.  But newer image browsers such as XnView make use of the Exif thumbnail,
    and so the thumbnails would be different from the image itself.  Note that the rotation tag also
    needed to be cleared (-norot option).
    <br>
    Typically, only images that are shot in portrait orientation are afflicted with this.  You can use
    the -orp option to tell jhead to only operate on images that are upright.
    <p>

    This option relies on 'mogrify' program (from ImageMagick) to regenerate the thumbnail.
    Linux users often already have this tool pre-installed.  Windows users have to go and download it.
    This option only works if the image already contains a thumbail.
</table>

<h3>Rotation tag manipulation</h3>
<table cellpadding=5>
<tr valign=top>
    <td><b>-autorot
    <td>
        Using the 'Orientation' tag of the Exif header, rotate the image so that it is upright.
        The program 'jpegtran' is used to perform the rotation.  This program is present in most 
        Linux distributions.  For windows, you need to get a copy of it.
        After rotation, the orientation tag of the Exif header is set to '1' (normal orientation).  
        The Exif thumbnail is also rotated.   Other fields of the Exif header, 
        including dimensions are untouched, but the JPEG height/width are adjusted.<br>
        This feature is especially useful with newer digital cameras, which set the orientation
        field in the Exif header automatically using a built in orientation sensor in the camera.

<tr valign=top>
    <td><b>-norot
    <td>
        Clears the Exif header rotation tag without altering the image.
        You may find that your images have rotation tags in them from your camera, but you already 
        rotated them with some lossless tool without clearing the rotation tag.
        Now your friendly browser rotates the images on you again because the image rotation
        tag still indicates the image should be rotated.  Use this option to fix this problem.
        You may also want to regenerate the thumbnail using the -rgt option.
</table>


<h3>Output verbosity control</h3>
<table cellpadding=5>


<tr valign=top><td><b>-h
<td>Displays summary of command line options.

<tr valign=top><td><b>-v
<td>Makes the program even more verbose than it already is.  Like DOS programs, and unlike
    UNIX programs, Jhead gives feedback as to what it is doing, even when nothing goes wrong.
    Windows user that I am, when something doesn't give me feedback for 20 seconds, I assume
    its crashed.

<tr valign=top><td><b>-q
<td>Makes the progran mot spit out messages on success - more like the "Silence is golden" Unix way.    its crashed.

<tr valign=top><td><b>-V
<td>Print version info and compilation date.

<tr valign=top><td><b>-Exifmap
<td>Show a map of the bytes in the Exif header.  Useful when analyzing strange Exif headers,
    not of much use to non software developers.

<tr valign=top><td><b>-se
<td>Suppress error messages relating to corrupt Exif header structure.

<tr valign=top><td><b>-c
<td>Concise output.  This causes picture info to be summarized on one line instead of several.
    Useful for grep-ing through images, as well as importing into spread sheets (data is space
    delimited with quotes as text qualifier).

</table>


<h3>File matching and selection</h3>
<table cellpadding=5>

<tr valign=top><td><b>-model
<td>Restricts processing of files to those whose camera model, as indicated by the Exif image
    information, contains the substring specified in the argument after '-model'.
    For example, the following command will list only images that are from an S100 camera:
    <p>
    jhead -model S100 *.jpg<p>
    <p>
    I use this option to restrict my JPEG re-compressing to those images that came from my 
    Cannon S100 digicam, (see the -cmd option).

<tr valign=top>
<td><b>-exonly
<td>Skip all files that don't have an Exif header.  This skips all files that did not
    come directly from the digital camera, as most photo editing software does not 
    preserve the Exif header when saving pictures.

<tr valign=top><td><b>-cmd&lt;command&gt;
<td>Executes the specified command on each Jepg file to be processed.<p>
    The Exif section of each file is read before running the command, and re-inserted
    after the command finishes.
    <p>
    This is useful for using jhead's file globbing capability for processing a whole
    directory tree of files.
    <p>
    It's also useful for restoring the exif header after operatiosn that wipe out
    the Exif metadata.  Most programs today however will keep the Exif metadata
    intact, so this is less important than it used to be.

<tr valign=top><td><b>-orp -orl
<td>Operate only on images with portrait (-orp) or landscape (-orl) aspect ratio.<br>
    Please note that this is solely based on jpeg width and height values.  Some browsers may auto
    rotate the image on displaying it based on the Exif orientation tag, so that images shot
    in portrait mode are displayed as portrait.  However, the image itself may not be stored in
    portrait orientation.
    The -autorot and -norot options are useful for dealing with rotation issues.
                                                                               
<tr valign=top><td><b>-r
<td>The recursive feature of version 1.0 never worked to my satisfaction, and I replaced it 
    with my recursive file globbing code in the Windows version.  See below.

</table>

<h3>Bugs and Shortcomings</h3>
<ul>
    After jhead runs a program to rotate or resize an image, the image dimensions and thumbnail 
    in the Exif header are not adjusted.
    <p>
    Modifying of Exif header data is very limited, as Jhead internally only has a read only
    implementation of the file system contained in the Exif header.  For the most part, Exif
    can only modify pre-existing fixed-length fields in the header.
    <p>

    Most Canon digital SLR cameras fail to adjust the effective sensor resolution when shooting at less
    than full resolution, causing jhead to incorrectly miscalculate the sensor width and 35mm equivalent 
    focal length.  The same can result from resizing photos with Photoshop, which will manipulate
    parts of the Exif header.
    This is often reported as a bug in Jhead, but Jhead can't do much about incorrect data.
</ul>

<h3>Name globbing and recursive directories under Windows</h3>
<ul>
    Name globbing means matching wildcard patterns to actual file names.  If you know what this
    term means, you are probably annoyed at how programs on Windows typically handle this.
    The Win32 version of this program goes beyond the pattern matching that Windows provides,
    and allows you to specify fancy UNIX-like patterns such as:
    <p>
    <font size = 2 face="courier">&nbsp jhead c:\pix\199*\*\*.jpg</font>
    <p>
    This program goes one step beyond beyond that in that "**" as a path component means any
    level of subdirectories.  The invocation
    <p>
    <font size = 2 face="courier">&nbsp jhead c:\**\*.jpg</font>
    <p>
    will find ALL Jpegs files on the c: drive, including those in the root directory.
    The <font size = 2 face="courier">**</font>
    only works if it is the only part of that path component.  For example, the path
    <font size = 2 face="courier">'c:\a**\*.jpg'</font>
    will not recurse.
    The <font size = 2 face="courier">'**'</font>
    recursive expansion is ONLY supported on the Windows version.   The code is in the module 'myglob.c',
    if you want to reuse it (I certainly intend to reuse that code for other applications).
    Under UNIX, the shell's wildcard expansion is
    pretty decent already, and dealing with the convoluted nature of some UNIX file layouts,
    doing better would have been much more of a challenge.
</ul>

<h3>Programs I use with Jhead</h3>
<b>ImageMagick</b><br>
<ul>
I use the MOGIRIFY command from ImageMagick to do batch conversions and re-compresses of images.
If you use Linux, you probably already have ImageMagick on your system (just type 'mogrify' at the
command prompt to see if you have it).  For Windows users, you have to download it from:
<a href="http://www.imagemagick.org"> http://www.imagemagick.org</a><p>
Image Magick is one of those programs that preserves comment and Exif headers, although older
versions do not.
</ul>
<b>JPEGTRAN</b><br>
<ul>
If you use Linux you probably also already have this program.  For windows, it's hard to find a 
pre-built binary on the web.  The <a href="http://www.ijg.org"> Independent JPEG
Group</a>'s website only has the source code.<p>
There's a fancier version, with pre-built Windows binaries and a lossless cropping feature added at:
<a href="http://sylvana.net/jpegcrop"> http://sylvana.net/jpegcrop</a>.
</ul>

<b>XnView</b><br>
<ul>
<a href="http://www.xnview.com">XnView</a> is an excellent, small, fast, and free graphical image browser.
It makes use of jpeg thumbnails for the thumbnail view.  On account of Xnview, I added
options to fix or regenerate the thumbnails to jhead, so that I could regenerate the thumbnails
for images where the thumbnail had gotten out of sync with the image.
<br>
Mac and Linux versions of XnView are also available.
</ul>

<b>wrjpgcom / rdjpgcom</b><br>
<ul>
You can use these programs to write and extract COM markers from JPEG images respectively.  Although I always
use my jhead program for this feature, the wrjpgcom and rdjpgcom programs are extremely simple and very
suitable for use with perl or shell scripts to process lots of images.  These programs are part of most 
Linux distributions as part of the libjpg package (along with jpegtran)
</ul>
<p><br>
Jhead homeage: <a href="http://www.sentex.net/~mwandel/jhead">http://www.sentex.net/~mwandel/jhead</a><br>
Last Updated: Jan 30 2013<p>