[Octave-bug-tracker] [bug #49613] image package - regionprops.m majoraxislength broken

[Hartmut]

URL:
  <http://savannah.gnu.org/bugs/?49613>

                 Summary: image package - regionprops.m majoraxislength broken
                 Project: GNU Octave
            Submitted by: hardy
            Submitted on: Tue 15 Nov 2016 09:33:59 PM GMT
                Category: Octave Forge Package
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: Regression
                  Status: None
             Assigned to: None
         Originator Name: 
        Originator Email: 
             Open/Closed: Open
         Discussion Lock: Any
                 Release: dev
        Operating System: Any

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Details:

This problem happens with the current version 2.6.1 of the image package. It
still worked fine with the older version of regionprops.m that is in the
release image-2.4.1.

The property "majoraxislenght" and "minoraxislength" seem to be corrupted
somewhere on their way through regionprops.m. If I observe this right, the
results are fine when I only request those properties from a single region.
But once I request those properties simultanously from several regions at
once, I get corrupted results.

Here is a small script to reproduce the behavior. It uses the attached
png-file "rechtecke.png":


clear, close all

I = imread('rechtecke.png');
schwelle = graythresh(I);
BW = im2bw(I, schwelle);
L = bwlabel(BW);
L_rgb = label2rgb(L, 'hsv');
imshow(L_rgb);
title('labelled regions');

props = regionprops(L,'MajorAxisLength','MinorAxisLength');
major=[props.MajorAxisLength]';
minor=[props.MinorAxisLength]';
figure, plot(major, minor, 'x');
xlabel('major axis length');
ylabel('minor axis length');


The second plot obviously does not show the correct major and minor axis
length with image-2.6.1. If you use image-2.4.1 instead you can see the
correct and expected result. I will also attach those two screenshots.



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File Attachments:


-------------------------------------------------------
Date: Tue 15 Nov 2016 09:33:59 PM GMT  Name: rechtecke.png  Size: 6kB   By:
hardy

<http://savannah.gnu.org/bugs/download.php?file_id=38977>
-------------------------------------------------------
Date: Tue 15 Nov 2016 09:33:59 PM GMT  Name: correct-result_image-2.4.1.png 
Size: 10kB   By: hardy

<http://savannah.gnu.org/bugs/download.php?file_id=38978>
-------------------------------------------------------
Date: Tue 15 Nov 2016 09:33:59 PM GMT  Name: wrong-result_image-2.6.1.png 
Size: 9kB   By: hardy

<http://savannah.gnu.org/bugs/download.php?file_id=38979>

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