bugGNU Octave - Bugs: bug #43893, image package: Incorrect result of...

 
 

bug #43893: image package: Incorrect result of erosion and dilation

Submitted by:  None
Submitted on:  Fri 26 Dec 2014 06:07:36 PM UTC  
 
Category: Octave Forge PackageSeverity: 3 - Normal
Priority: 5 - NormalItem Group: Incorrect Result
Status: InvalidAssigned to: None
Originator Name: fachriOriginator Email: -unavailable-
Open/Closed: ClosedRelease: other
Operating System: GNU/Linux

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Sat 27 Dec 2014 04:26:37 PM UTC, comment #2:

Your images look fine to me. Note that the white regions of your image (pixels of value true) are the objects/foreground while the black regions (pixels with value false) are the background.

The visual effect of erosion is shrinking of objects (white regions become smaller, very small objects disappear) while the effect of dilation is is the opposite. Your screenshoot shows this so the results are as expected.

The only reason I can see someone expecting the opposite is if you are an ImageJ user. ImageJ uses an inverted LUT for binary images by default --- background is white, objects are white --- which can be confusing for users of everything else. If so, you may want to use the complement of your image (use imcomplement of the image package).

I'm closing this is an invalid (but please comment if we interpreted this wrong and we will reopen the bug).

Carnë Draug <carandraug>
Project Member
Fri 26 Dec 2014 08:40:03 PM UTC, comment #1:

Why do you think the results are reversed? Your screenshot looks fine for me. See also the ML docu here http://de.mathworks.com/help/images/ref/imerode.html for some examples.

Andreas Weber <andy1978>
Project Member
Fri 26 Dec 2014 06:07:36 PM UTC, original submission:

Dear GNU Octave Developer

I am using GNU Octave version 3.8.1 at Ubuntu 14.04 with image package 2.2.0 (screenshot of packcage list attached as version.png). When I use imerode to erode image and imdilate to dilate image, I found the result is reversed. imerode resulted a dilated image and vice versa. I attached the image result from my experiment (result.png). I hope it help and can be fixed as soon as possible.

Thank you very much.

Anonymous

 

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Attached Files
file #32716:  version.png added by None (26KiB - image/png)
file #32717:  Result.png added by None (117KiB - image/png)

 

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  • -unavailable- added by avinoam
  • -unavailable- added by jwe (Updated the item)
  • -unavailable- added by None (Submitted the item)
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    Follow 8 latest changes.

    Date Changed By Updated Field Previous Value => Replaced By
    Sat 27 Dec 2014 04:26:37 PM UTCcarandraugStatusNone=>Invalid
      Open/ClosedOpen=>Closed
      Release3.8.1=>other
      SummaryIncorrect result of erosion and dilation=>image package: Incorrect result of erosion and dilation
    Fri 26 Dec 2014 06:55:40 PM UTCavinoamCarbon-Copy-=>Added avinoam
    Fri 26 Dec 2014 06:22:08 PM UTCjweCategoryOctave Function=>Octave Forge Package
    Fri 26 Dec 2014 06:07:36 PM UTCNoneAttached File-=>Added version.png, #32716
      Attached File-=>Added Result.png, #32717

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