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[Octave-bug-tracker] [bug #46547] image package: canny detector in edge(


From: Hartmut
Subject: [Octave-bug-tracker] [bug #46547] image package: canny detector in edge() should use LoG as first step
Date: Thu, 26 Nov 2015 19:29:22 +0000
User-agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:42.0) Gecko/20100101 Firefox/42.0

URL:
  <http://savannah.gnu.org/bugs/?46547>

                 Summary: image package: canny detector in edge() should use
LoG as first step
                 Project: GNU Octave
            Submitted by: hardy
            Submitted on: Do 26 Nov 2015 19:29:21 GMT
                Category: Octave Forge Package
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: Matlab Compatibility
                  Status: None
             Assigned to: None
         Originator Name: 
        Originator Email: 
             Open/Closed: Open
         Discussion Lock: Any
                 Release: 4.0.0
        Operating System: Any

    _______________________________________________________

Details:

I moved this away from bug report #46099 (comment 2 of an anonymous use),
because it is a different and new topic. The following is a quote:
=========================================

I'm evaluating an image binarization code (originaly developed for Matlab)
with Octave (4.0.0) and image package (2.4.1). After some investigation on why
I'm getting worse results with Octave than with Matlab (R2012b), I've found
that edge function with 'Canny' method outputs a much noisier result with
Octave than with Matlab. In order to give an example, I've run the following
code with both software:

clear, close all;
I = imread('sample2.png');
thresholds = [5.2742e-004 0.3899];
BW = edge(I, 'Canny', thresholds);
imwrite(BW, 'result_edge_canny_sample2.png');


As one can see in the attached files, "Octave_result_edge_canny_sample2.png"
is much noisier than "ML2012b_result_edge_canny_sample2.png". As a result, the
binarized image (generated by the image binarization code, which uses edge
function with 'Canny' method) is also noisy and almost useless.



    _______________________________________________________

File Attachments:


-------------------------------------------------------
Date: Do 26 Nov 2015 19:29:21 GMT  Name: sample2.png  Size: 24kB   By: hardy

<http://savannah.gnu.org/bugs/download.php?file_id=35565>
-------------------------------------------------------
Date: Do 26 Nov 2015 19:29:21 GMT  Name: Octave_result_edge_canny_sample2.png 
Size: 3kB   By: hardy

<http://savannah.gnu.org/bugs/download.php?file_id=35566>
-------------------------------------------------------
Date: Do 26 Nov 2015 19:29:21 GMT  Name: ML2012b_result_edge_canny_sample2.png
 Size: 823B   By: hardy

<http://savannah.gnu.org/bugs/download.php?file_id=35567>

    _______________________________________________________

Reply to this item at:

  <http://savannah.gnu.org/bugs/?46547>

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