[gnuastro-devel] [sr #109227] Cropping of small regions fails

[Lee Kelvin]

URL:
  <http://savannah.gnu.org/support/?109227>

                 Summary: Cropping of small regions fails
                 Project: GNU Astronomy Utilities
            Submitted by: leeskelvin
            Submitted on: Thu 19 Jan 2017 05:21:21 PM GMT
                Category: ImageCrop
                Priority: 5 - Normal
                Severity: 4 - Important
              Item Group: Crash
                  Status: None
                 Privacy: Public
             Assigned to: None
        Originator Email: 
             Open/Closed: Open
         Discussion Lock: Any
        Operating System: GNU/Linux

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Details:

When attempting to crop a region with either axis of length 1 pixel or 2
pixels, ImageCrop fails, with different errors.

The attached file 'input.fits' was used to test. This file is a 9x9 FITS image
which was cropped from a larger image using the NASA HEASARC program
'fitscopy'. Note that this file was initially produced to test the feature
request in support item #109226.

First, I attempted to crop a 2x2 pixel region from the lower-left corner of
the image. The command and resultant FITSIO error are shown below:

$ astimgcrop --section=1:3,1:3 input.fits 
ImageCrop started on Thu Jan 19 17:06:39 2017
  - Read metadata of 1 images.                    0.000293 seconds

FITSIO status = 307: bad first row number
Attempt to read past end of array:
  Image has  4 elements;
  Tried to read 3 elements starting at element 3.
astimgcrop: Error in CFITSIO, see above.

An output file was produced of size 0 bytes.

Curiously, running this command with an aim to crop regions of varying
rectangular size fail, but only to a point. In my testing these dimensions
failed: 1:3,1:3; 1:3,1:4; 1:3,1:5. However, 1:3,1:6 succeeded. Note however
that varying the dimension of the 1st axis whilst keeping the second axis
length fixed always fails (e.g. 1:9,1:3 fails).

Second, I attempted to crop a 1x1 pixel region from the lower-left corner of
the image. The command and resultant error are shown below:

$ astimgcrop --section=1:2,1:2 input.fits 
ImageCrop started on Thu Jan 19 17:08:08 2017
  - Read metadata of 1 images.                    0.000493 seconds
astimgcrop: the bottom left corner coordinates cannot be larger or equal to
the top right's! Your section string (1:2,1:2) has been read as: bottom left
coordinate (1, 1) to top right coordinate (1, 1)

No output file is produced after running this second command.

This second command always fails in my testing for any dimension rectangular
region where one of the axes is of length 1 pixel.

I believe the causes of these two errors to be separate, but I am unsure,
hence my listing them together in this bug report. I'm unsure what may be the
cause for the former bug, but it seems like the cause of the latter may be an
overly restrictive internal hard-coded limitation.

Regards, 
Lee Kelvin




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File Attachments:


-------------------------------------------------------
Date: Thu 19 Jan 2017 05:21:22 PM GMT  Name: input.fits  Size: 8kB   By:
leeskelvin

<http://savannah.gnu.org/support/download.php?file_id=39514>

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