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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: Fri, 11 Dec 2015 12:56:29 +0000
User-agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:42.0) Gecko/20100101 Firefox/42.0

Follow-up Comment #12, bug #46547 (project octave):

I've used the following script to have a look at the Matlab result for an
automatic threshold result of our sample image:


clear, close all;
I = imread('sample2.png');
BW = edge(I, 'Canny');
imwrite(BW, 'ML2013b_autothresh_canny_sample2.png');


The resulting image is attached both 
* as image file, and 
* as a screenshot with a comparison between the Matlab result and the Octave
result
(with all patches applied, including the one in comment #7).

My CONCLUSION: Matlab gives the same "not so nice" result when used without an
explicit threshold value on this image.

So I would now strongly vote for option 3: APPLY ALL PATCHES to the Octave
version of edge.m. This gives
* good quality edge images as results (with an individually fine tuned
threshold value)
* a very good Matlab compatibility of the results, with and without explicitly
given thresholds
* a worse result on this single example image, when used without explicit
thresholds

So the worse result  (with auto thresholds) on this sample image is the price
we need to pay for improved Matlab compatibility. 


(file #35698, file #35699)
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Additional Item Attachment:

File name: ML2013b_autothresh_canny_sample2.png Size:2 KB
File name: Compare_left=Matlab2013b_right=Octave+AllPatches.png Size:9 KB


    _______________________________________________________

Reply to this item at:

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

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