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.TH MADD 1 "Dec 2016" "Montage 5" "Montage"
.SH NAME
mAdd \- Re-project and mosaic your images, with background rectification
.SH SYNOPSIS
mAdd [\-p \fIimgdir\fP] [\-n(o-areas)] [\-a mean|median|count] [\-e(xact-size)] [\-d \fIlevel\fP] [\-s \fIstatusfile\fP] images.tbl template.hdr out.fits
.SH DESCRIPTION
Coadd the reprojected images in an input list to form an output mosaic with FITS header keywords specified in a header file. Creates two output files, one containing the coadded pixel values, and the other containing coadded pixel area values. The pixel area values can be used as a weighting function if the output pixel values are themselves to be coadded with other projected images, and may also be used in validating the fidelity of the output pixel values.
.SH OPTIONS
.TP
\-p \fIimgdir\fP
Specifies path to directory containing reprojected images. If the \-p switch is not included, mAdd will look for the input images in the current working directory.
.TP
\-n
Co-addition ignores weighting by pixel areas and performs coaddition based only on pixel positions. This flag refers to \fIinput\fP images; the area file for the output image will still be created.
.TP
\-a \fItype\fP
Select type of averaging to be done on accumulated pixel values (either mean or median). To generate a map showing counts of how many times each pixel was overlapped by the input images, use count.
.TP
\-e
Enables exact size mode. The output image will match the header template exactly, instead of shrinking the output to fit the data.
.TP
\-d \fIlevel\fP
Turns on debugging to the specified level (1\-3).
.TP
\-s \fIstatusfile\fP
mAdd output and errors will be written to \fIstatusfile\fP instead of stdout.
.SH ARGUMENTS
.TP
images.tbl
ASCII table (generated by mImgtbl) containing metadata for all images to be coadded.
.TP
template.hdr
FITS header template to be used in generation of output FITS
.TP
out.fits
Name of output FITS image.
.SH RESULT
If successful, mAdd creates a FITS file \fBout.fits\fP that is a coadd of all the FITS files in the table \fBimages.tbl\fP, according to the header template given. A corresponding \fBout_area.fits\fP is also created.
.SH MESSAGES
.TP
OK
[struct stat = "OK", time=\fItime\fP]
.TP
ERROR
MPI initialization failed
.TP
ERROR
Invalid argument for \-a flag
.TP
ERROR
Cannot open status file: \fIstatusfile\fP
.TP
ERROR
Invalid image metadata file: \fIfilename\fP
.TP
ERROR
Need columns: cntr,fname, crpix1, crpix2, cdelt1, cdelt2, naxis1, naxis2, crval1, crval2 in image list
.TP
ERROR
Memory allocation failed
.TP
ERROR
Too many open files
.TP
ERROR
Input wcsinit() failed.
.TP
ERROR
Failed to allocate enough memory for output arrays
.TP
ERROR
Bad WCS in header template.
.TP
ERROR
Images are not in same pixel space.
.TP
ERROR
Template file not found.
.TP
ERROR
\fIFITS library error\fP
.TP
ERROR
\fIgeneral error message\fP
.SH EXAMPLES
.PP
The following example runs \fBmAdd\fP on 4 FITS images, generating the output file \fBmosaic.fits\fP. Related files are images.tbl and template.hdr.
.TP
$ mAdd \-p proj images.tbl template.hdr output/mosaic.fits
[struct stat="OK", time=1]
.SH BUGS
The drizzle algorithm has been implemented but has not been tested
in this release.
.PP
If a header template contains carriage returns (i.e., created/modified
on a Windows machine), the cfitsio library will be unable to read it
properly, resulting in the error: [struct stat="ERROR", status=207,
msg="illegal character in keyword"]
.PP
It is best for the background correction algorithms if the area
described in the header template completely encloses all of the input
images in their entirety. If parts of input images are "chopped off"
by the header template, the background correction will be affected. We
recommend you use an expanded header for the reprojection and
background modeling steps, returning to the originally desired header
size for the final coaddition. The default background matching assumes
that there are no non-linear background variations in the individual
images (and therefore in the overlap differences). If there is any
uncertainty in this regard, it is safer to turn on the "level only"
background matching (the "\-l" flag in mBgModel.
.PP
Although the memory limitation for output images has been overcome in
versions 2.x and above of Montage, it is still possible (though
unlikely) to create an out-of-memory situation due to the size and
number of input images. mAdd builds the output image one row at a
time, and stores every pixel from any input image that contributes to
that row in memory.
.PP
If you have a large enough mosaic, it is almost always more efficient
(and often easier on the user) to tile it. There are tools in Montage
to help with this and these have been brought together under
mAddExec. In fact, even if you want a single output image, it may be
faster to do it in two steps: mAddExec to create a set of tiles, and
then mAdd to make a final mosaic from these tiles. There is absolutely
no loss of information in doing this.
.SH COPYRIGHT
2001-2015 California Institute of Technology, Pasadena, California
.PP
If your research uses Montage, please include the following
acknowledgement: "This research made use of Montage. It is funded by
the National Science Foundation under Grant Number ACI-1440620, and
was previously funded by the National Aeronautics and Space
Administration's Earth Science Technology Office, Computation
Technologies Project, under Cooperative Agreement Number NCC5-626
between NASA and the California Institute of Technology."
.PP
The Montage distribution includes an adaptation of the MOPEX algorithm
developed at the Spitzer Science Center.
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