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

 
 

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

Submitter:  None
Submitted:  Fri 26 Dec 2014 06:07:36 PM UTC
   
 
Category:  Octave Package Severity:  3 - Normal
Priority:  5 - Normal Item Group:  Incorrect Result
Status:  Invalid / Not an Octave Bug Assigned to:  None
Originator Name:  fachri Originator Email:  -email is unavailable-
Open/Closed:  * Closed Release:  * other
Operating System:  * GNU/Linux Fixed Release:  None
Planned Release:  None
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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>
Group 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>
Group 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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    Follow 8 latest changes.

    Date Changed by Updated Field Previous Value => Replaced by
    2014-12-27 carandraug StatusNone Invalid / Not an Octave Bug
        Open/ClosedOpen Closed
        Release3.8.1 other
        SummaryIncorrect result of erosion and dilation image package: Incorrect result of erosion and dilation
    2014-12-26 avinoam Carbon-Copy- Added avinoam
    2014-12-26 jwe CategoryOctave Function Octave Package
    2014-12-26 None Attached File- Added version.png, #32716
        Attached File- Added Result.png, #32717

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