bugGNU Octave - Bugs: bug #59502, imread doesn't read correctly...


bug #59502: imread doesn't read correctly 1-bit depth .pgm file

Submitter:  alexis rivera <arivera>
Submitted:  Mon 23 Nov 2020 02:17:54 AM UTC
Category:  Octave Function Severity:  3 - Normal
Priority:  5 - Normal Item Group:  Incorrect Result
Status:  None Assigned to:  None
Originator Name:  alexis Open/Closed:  * Open
Release:  * 5.2.0 Operating System:  * Microsoft Windows
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Tue 24 Nov 2020 07:40:35 PM UTC, comment #3: 

This might be a duplicate of bug #51264 (or bug #41584 ).

Hartmut <hardy>
Mon 23 Nov 2020 03:31:40 AM UTC, comment #2: 

If I change the maximum gray value from 1 to 2 (in the test.pgm header), it would work. But I think 1 should work as well:



Dmitri A. Sergatskov <dasergatskov>
Mon 23 Nov 2020 02:36:57 AM UTC, comment #1: 

Confirm with current stable on linux.
The problem appears to be with graphicsmagick library.
"gm display test.pgm" does not show ellips.
Using imagemagick works fine ("display test.pgm")


Dmitri A. Sergatskov <dasergatskov>
Mon 23 Nov 2020 02:17:54 AM UTC, original submission:  


I created a 64x64 1-bit depth pgm file containing an ellipse.  When I read it as follows:
X = imread('test.pgm')

The result is a 64 matrix of all ones.

However, imread works fine with a 64x64 .pbm file
X = imread('test.pbm') % this works

I am running octave-5.2.0_1-w32 on a windows 10 machine.  Another detail is that I downloaded the .zip file instead of the installer. 


alexis rivera <arivera>


(Note: upload size limit is set to 16384 kB, after insertion of the required escape characters.)

Attach Files:

Attached Files
file #50317:  test.pgm added by arivera (4KiB - application/octet-stream - test images)
file #50318:  test.pbm added by arivera (521B - application/octet-stream - test images)


Depends on the following items: None found

Items that depend on this one: None found


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    Follow 2 latest changes.

    Date Changed by Updated Field Previous Value => Replaced by
    2020-11-23 arivera Attached File- Added test.pgm, #50317
        Attached File- Added test.pbm, #50318

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