Scroll to navigation

WARP(1) User Commands WARP(1)


Warp - warp (transform) input dataset


astwarp [OPTION...] ASTRdata


Warp is part of GNU Astronomy Utilities 0.14. Warp will warp/transform the input image using an input coordinate matrix. Currently it accepts any general projective mapping (which includes affine mappings as a subset).

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

All options and their values:
$ astwarp -P
Inputs/Outputs and options:
$ info astwarp
Full section in manual/book:
$ info Warp
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

Warp options:

Header keyword number to end reading WCS.
Header keyword number to start reading WCS.
-h, --hdu=STR/INT
Extension name or number of input data.
-I, --ignorecase
Ignore case in matching/searching columns.
-C, --coveredfrac=FLT
Acceptable fraction of output pixel covered.
-D, --dontdelete
Don't delete output if it exists.
-k, --keepwcs
Do not apply warp to input's WCS
-K, --keepinputdir
Keep input directory for automatic output.
-o, --output=STR
Output file name.
-T, --type=STR
Type of output: e.g., int16, float32, etc...
-a, --align
Align the image and celestial axes.
-c, --centeroncorner
Center of coordinates on first pixel corner.
-e, --shear=FLT[,FLT]
Shear along the given axis(es).
-f, --flip=INT[,INT]
Flip along the given axis(es).
-m, --matrix=STR
Raw transformation matrix, highest priority.
-p, --project=FLT[,FLT]
Project along the given axis(es).
-r, --rotate=FLT
Rotate by the given angle in degrees.
-s, --scale=FLT[,FLT]
Scale along the given axis(es).
-t, --translate=FLT[,FLT]
Translate along the given axis(es).
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 Warp is maintained as a Texinfo manual. If the info and Warp programs are properly installed at your site, the command
info Warp

should give you access to the complete manual.

January 2021 GNU Astronomy Utilities 0.14