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CROP(1) User Commands CROP(1)


Crop - crop regions of a dataset


astcrop [OPTION...] [Crop-Identifier] ASTRdata ...


Crop is part of GNU Astronomy Utilities 0.14. Crop will create cutouts, thumbnails, postage stamps or crops of region(s) from input image(s) using image or celestial coordinates. If muliple crops are desired, a catalog must be provided. When in WCS mode, if the cut out covers more than one input image, all overlapping input images will be stitched in the output.

For more information, please run any of the following commands. In particular the second contains a very comprehensive explanation of Crop's invocation: expected input(s), output(s), and a full description of all the options.

All options and their values:
$ astcrop -P
Inputs/Outputs and options:
$ info astcrop
Full section in manual/book:
$ info Crop
Full Gnuastro manual/book:
$ info gnuastro

If you couldn't find your answer in the manual, you can get direct help from experienced Gnuastro users and developers. For more information, please run:

$ info help-gnuastro

Crop options:

Header keyword number to stop reading WCS.
Header keyword number to start reading WCS.
-h, --hdu=STR/INT
Extension name or number of (all) input(s).
-O, --mode=STR
Coordinate mode 'img' or 'wcs'.
-z, --zeroisnotblank
0.0 in float or double images are not blank.
-b, --noblank
Remove parts of the crop box out of input image.
-D, --dontdelete
Don't delete output if it exists.
-K, --keepinputdir
Keep input directory for automatic output.
-o, --output=STR
Output file name.
Write crop in primary/zero-th HDU of output.
-p, --suffix=STR
Suffix (postfix) of cropped images.
Table fmt: 'fits-ascii', 'fits-binary', 'txt'.
-T, --type=STR
Type of output: e.g., int16, float32, etc...
Crop by center
Width (in pixels) of box at center to check.
-c, --center=FLT[,...]
Central coordinates of a single crop.
-w, --width=FLT[,...]
Width when crop is defined by its center.
Crop by center (when a catalog is given)
HDU of catalog, if it is a FITS table.
-C, --catalog=STR
Input catalog filename.
-I, --ignorecase
Ignore case in matching/searching columns.
-n, --namecol=STR/INT
Column no./info of crop filename (no suffix).
Select column(s): 'name', 'unit', 'comment'.
-x, --coordcol=STR/INT
Column no./info containing coordinates.
Crop by region
-l, --polygon=STR
Polygon vertices of region to crop, keep inside.
Keep the polygon's outside, mask the inside.
Sort polygon vertices as counter-clockwise.
-s, --section=STR
Image section string specifying crop range.
Operating modes:
-?, --help
give this help list
List all config files and variables read.
BibTeX citation for this program.
Read configuration file STR immediately.
Do not parse any more configuration files.
Information about output(s) in a log file.
Minimum bytes in array to not use ram RAM.
-N, --numthreads=INT
Number of CPU threads to use.
Only run if the program version is STR.
-P, --printparams
Print parameter values to be used and abort.
Don't print mmap'd file's name and size.
-q, --quiet
Only report errors, remain quiet about steps.
-S, --setdirconf
Set default values for this directory and abort.
give a short usage message
-U, --setusrconf
Set default values for this user and abort.
-V, --version
print program version

Mandatory or optional arguments to long options are also mandatory or optional for any corresponding short options.

GNU Astronomy Utilities home page:


Report bugs to


Copyright © 2015-2021, Free Software Foundation, Inc. License GPLv3+: GNU General public license version 3 or later.
This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law.

Written/developed by Mohammad Akhlaghi


The full documentation for Crop is maintained as a Texinfo manual. If the info and Crop programs are properly installed at your site, the command
info Crop

should give you access to the complete manual.

January 2021 GNU Astronomy Utilities 0.14