mImgtbl - Online in the Cloud

PROGRAM:

NAME

mImgtbl - Generate metadata from a set of FITS images

SYNOPSIS

mImgtbl [-rcadb] [-s statusfile] [-f fieldlistfile] [-t imglist] directory images.tbl

DESCRIPTION

mImgtbl extracts the FITS header geometry information from a set of files and creates an
ASCII image metadata table which is used by several of the other programs. It only
collects data from headers that comply with the FITS standard, but reports a count of
images that fail that check.

OPTIONS

-r mImgtbl can also be used as a standalone program to gather image metadata for other
purposes (to populate a database, as a basis for spatial coverage searches, etc.)
In this case it is often desirable to collect information on all the files in a
directory tree recursively. The "-r" (recursive) flag instructs mImgtbl to search
the given directory and all its subdirectories recursively.

-c The "-c" (corners) option in mImgtbl will cause eight extra columns to be added to
the output metadata table containing the RA, Dec coordinates (ra1, dec1, ... ra4,
dec4) of the image corners. The output is always Equatorial J2000, even if the
input is some other system. Though not required for the core proessing modules, we
recommend using this option, as some of the utilities may require corner locations
to function properly.

-C The original version of mImgtbl ignored cube structure in the files; it only looked
at the first two dimensions and associated WCS parameters. When cube processing
was added to Montage, it was necessary to examine the third and fourth dimensions
(if they exist) and so some additional columns were added to the mImgtbl output
(e.g., NAXIS4, CRVAL3). It is still often the case where all of the new columns
would be blank, so to save space the old mode output can be invoked using the "-C"
(no-cube) option. This is cosmetic for the most part, since the "four-dimensional"
output is perfectly valid for further processing of 2D data.

-a By default, mImgtbl ignores FITS files with names ending in _area (i.e.
name_area.fits), assuming them to be Montage-created area images. If you want to
generate information on these images, or if you have images with _area in the title
other than those generated by Montage, you should turn on this flag to force
mImgtbl to look at all images in the directory.

-d Turn on debugging

-b When this switch is set, mImgtbl will explicitly output each FITS file it finds
that does not appear to be valid, along with information on the error.

-s statusfile
Output and errors are written to statusfile instead of being written to stdout.

-f fieldlistfile
Used to specify a fieldlist, which will list additional keywords to be read from
the FITS headers and included in the output table. Fieldlists should specify the
keyword name, type (int,char,double), and size. Example: example.fieldlist.

-t imglist
mImgtbl will only process files with names specified in table imglist, ignoring any
other files in the directory. Example: example.imglist.

ARGUMENTS

directory
Path to directory containing set of input FITS files.

images.tbl
Path of output metadata table.

RESULT

Output table contains metadata information from all readable FITS files in the directory
specified by directory. count is the number of records in the table, and badfits is the
number of files for which FITS metadata could not be extracted.

OUTPUT COLUMNS

cntr A unique counter (row number)

ra,dec Image position in decimal degree format

cra,cdec
Right ascension in HHMMSS.SS format. Declination in DDMMSS.S format

naxis1, naxis2
The size of the image in pixels for dimensions 1 and 2

ctype1, ctype2
The coordinate system (the first four characters) and WCS map projection (last
three characters) for dimensions 1 and 2

crpix1, crpix2
The pixel coordinates of the reference location (can be fractional and can be off
the image) for dimensions 1 and 2

crval1, crval2
The coordinates of a reference location on the sky (often at the center of the
image) for dimensions 1 and 2

cdelt1, cdelt2
The pixel scale (in degrees on the sky per pixel) at the reference location for
dimensions 1 and 2

crota2 The rotation angle from the "up" direction to the celestial pole

equinox
Precessional year associated with the coordinate system

hdu Numerical identifier for the FITS extension that the image info is extracted from,
for FITS files with multiple HDUs.

size Filesize (in bytes) of the input FITS file

fname The path to the input FITS file

MESSAGES

OK [struct stat="OK", count=count, badfits=badfits]

ERROR Illegal argument: -arg

ERROR Cannot open status file: statusfile

ERROR Cannot open field list file: fieldlistfile

ERROR Cannot open image list file: imgfile

ERROR Image table needs column fname/file

ERROR Illegal field name: string]

ERROR Illegal field type: string]

ERROR Cannot access directory

ERROR directory is not a directory

ERROR Can't open output table.

ERROR Can't open copy table.

ERROR Can't open tmp (in) table.

ERROR Can't open tmp (out) table.

ERROR Can't open final table.

ERROR FITS library error

EXAMPLES

The following example runs mImgtbl on a directory containing 14 2MASS images:

$ mImgtbl input/2mass images.tbl
[struct stat="OK", count=14, badfits=0]

Output: images.tbl.

Running mImgtbl on a directory that contains 3 bad FITS images, with the -c switch on:

$ mImgtbl -c input/2mass-bad images-corners.tbl
[struct stat="OK", count=14, badfits=3]

The output file is identical to the first example, but with the addition of 8 "corners"
columns: images-corners.tbl. The badfits counter in the output message reports on how
many images were found containing invalid header information.

When passed a field list file like this example, extra columns are extracted from the FITS
headers and inserted in the table:

$ mImgtbl -f example.fieldlist input/2mass images-expanded.tbl
[struct stat="OK", count=14, badfits=0]

The output file has additional columns as specified: images-expanded.tbl.

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