bugGNU Octave - Bugs: bug #42043, image(X, Y, Img) yields distorted...


bug #42043: image(X, Y, Img) yields distorted display

Submitted by:  Falk Tannhäuser <fata>
Submitted on:  Thu 03 Apr 2014 10:26:10 PM UTC  
Category:  Plotting Severity:  3 - Normal
Priority:  5 - Normal Item Group:  Regression
Status:  Fixed Assigned to:  None
Originator Name:  Falk Tannhäuser Open/Closed:  Closed
Release:  3.8.1 Operating System:  Microsoft Windows

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Fri 04 Apr 2014 06:53:44 PM UTC, comment #5: 

I fixed the issue in this changeset (http://hg.savannah.gnu.org/hgweb/octave/rev/3283ce934648).  Unfortunately you won't see the results until the next release (3.8.2).  But since the changes were only to m-files you could just grab image.m, imagesc.m from the hgweb interface and replace your local copies with the new files.

Rik <rik5>
Project Administrator
Fri 04 Apr 2014 04:19:08 PM UTC, comment #4: 

Done. See the attached .tar.bz2 archive.

(file #31126)

Falk Tannhäuser <fata>
Fri 04 Apr 2014 03:44:08 PM UTC, comment #3: 

I need to ask for another piece of information from Matlab.

Could you run this code and then upload the resulting file?

close all
image (1:5, 1:20, 255*eye(60))
axprop = get (gca);
save ('axprop.v6', 'axprop', '-v6')

If it doesn't work with a structure and '-v6' you could use '-v7', but it should be fine.

Rik <rik5>
Project Administrator
Fri 04 Apr 2014 12:28:55 PM UTC, comment #2: 

With Matlab version (R2012b) I get the following results (some line breaks removed):

ans = auto
ans =     4.0678   19.3220    1.0000
ans = auto
ans =      1     1     1

ans = auto
ans =     60    60     1
ans = auto
ans =     1     1     1

I also attach PNG files of the generated figures.

Falk Tannhäuser <fata>
Thu 03 Apr 2014 11:24:49 PM UTC, comment #1: 

I know why this is happening, but I need to figure out how Matlab behaves in order to maintain compatibility.  Could someone run the following test in Matlab ard report the results here?

image (1:5, 1:20, 255*eye(60))
daspect ('mode')
pbaspect ('mode')

image (255*eye(60))
daspect ('mode')
pbaspect ('mode')

Rik <rik5>
Project Administrator
Thu 03 Apr 2014 10:26:10 PM UTC, original submission:  

The following command yields a distorted picture display in Octave version 3.8.1 (Cygwin 64-bit / gnuplot), while a normal (i.e. almost square) picture is generated when replacing the file /usr/share/octave/3.8.1/m/image/image.m by the corresponding file from version 3.8.0:

image(1:5, 1:20, 255*eye(60))

See the two attached PNG files for the different results.
This strange behaviour breaks in particular the specgram() function from the signal package, which is how I noticed the problem.

Falk Tannhäuser <fata>


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

Attach Files:

Attached Files
file #31126:  axprop.tar.bz2 added by fata (5KiB - application/x-bzip2)
file #31122:  1.png added by fata (3KiB - image/png)
file #31123:  2.png added by fata (3KiB - image/png)
file #31117:  image_380.png added by fata (10KiB - image/png)
file #31118:  image_381.png added by fata (10KiB - image/png)


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    Follow 10 latest changes.

    Date Changed by Updated Field Previous Value => Replaced by
    2015-08-21 mtmiller Dependencies- => bugs #45807 is dependent
    2014-09-06 mtmiller Dependencies- => bugs #43159 is dependent
    2014-04-04 rik5 StatusNeed Info => Fixed
        Open/ClosedOpen => Closed
    2014-04-04 fata Attached File- => Added axprop.tar.bz2, #31126
    2014-04-04 fata Attached File- => Added 1.png, #31122
        Attached File- => Added 2.png, #31123
    2014-04-03 rik5 StatusNone => Need Info
    2014-04-03 fata Attached File- => Added image_380.png, #31117
        Attached File- => Added image_381.png, #31118

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