bugGNU Octave - Bugs: bug #31241, imrotate bad behaviour with...

 
 

bug #31241: imrotate bad behaviour with "Fourier" parameter

Submitted by:  zenko <zenko>
Submitted on:  Mon 04 Oct 2010 02:19:00 PM UTC  
 
Category: LibrariesSeverity: 3 - Normal
Priority: 5 - NormalItem Group: Incorrect Result
Status: Octave ForgeAssigned to: None
Originator Name: ZenkoOpen/Closed: Closed
Release: 3.2.4Operating System: GNU/Linux

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Tue 05 Oct 2010 09:26:11 AM UTC, comment #3:

Isn't imrotate an Octave Forge image package function? I think this bug should be reported/discussed on the Octave Forge mailing list and closed here since it is not really a bug in Octave.

John W. Eaton <jwe>
Project Administrator
Tue 05 Oct 2010 09:14:56 AM UTC, comment #2:

Hi again,

I've tried with jpg and png formats and it fails with both of them, I also tried your code and the results are in the attachments, you can see how the borders of the square are blurry, with color images it's worst because it returns an bw image.

The next two attachments are a test with GNU logo.

Please note that if I use any other method such as "bicubic" everything works fine.

(file #21620, file #21621, file #21622, file #21623)

zenko <zenko>
Tue 05 Oct 2010 01:44:10 AM UTC, comment #1:

Can you also post the image used? I have done a few simple tests like:

zz = zeros(100,100);
zz(40:60,40:60) = 1;
zz2 = imrotate(zz, 45, "Fourier");
imshow(zz2,[])

and everything looks fine. I would like to take a look at the image you are loading in to see if it is possibly a mix of the Fourier interpolation with JPG artifacts. Does this occur if the image was loaded from a lossless format?

John Swensen <jpswensen>
Mon 04 Oct 2010 02:19:00 PM UTC, original submission:

The function imrotate presents a bad behaviour when using "Fourier" parameter.

I've tried the 3.2.4 and 3.3.52 versions and the one that comes with ubuntu 10.04, all of them have the same bug. The following set of instructions cause bad behaviour:

img = imread("myimg.jpg");
imgr = imrotate(img,65,"Fourier");

The rotated image is not properly working, I attach the result as an image.

zenko <zenko>

 

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

Attach File(s):
   
   
Comment:
   

Attached Files
file #21620:  badsqar.png added by zenko (4KiB - image/png)
file #21621:  square.png added by zenko (2KiB - image/png)
file #21622:  badlogo.png added by zenko (85KiB - image/png)
file #21623:  logo.jpg added by zenko (17KiB - image/jpeg)

 

Depends on the following items: None found

Items that depend on this one: None found

 

Carbon-Copy List
  • -unavailable- added by jwe (Posted a comment)
  • -unavailable- added by jpswensen (Posted a comment)
  • -unavailable- added by zenko (Submitted the item)
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    Follow 7 latest changes.

    Date Changed By Updated Field Previous Value => Replaced By
    Tue 05 Oct 2010 09:26:11 AM UTCjweStatusNone=>Octave Forge
      Open/ClosedOpen=>Closed
    Tue 05 Oct 2010 09:14:56 AM UTCzenkoAttached File-=>Added badsqar.png, #21620
      Attached File-=>Added square.png, #21621
      Attached File-=>Added badlogo.png, #21622
      Attached File-=>Added logo.jpg, #21623
    Mon 04 Oct 2010 02:19:00 PM UTCzenkoAttached File-=>Added Screenshot-Untitled Window.png, #21609

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