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[Octave-bug-tracker] [bug #51724] image package: imregionalmax misbehave
From: |
Hartmut |
Subject: |
[Octave-bug-tracker] [bug #51724] image package: imregionalmax misbehaves on float images |
Date: |
Thu, 10 Aug 2017 14:23:11 -0400 (EDT) |
User-agent: |
Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:54.0) Gecko/20100101 Firefox/54.0 |
URL:
<http://savannah.gnu.org/bugs/?51724>
Summary: image package: imregionalmax misbehaves on float
images
Project: GNU Octave
Submitted by: hardy
Submitted on: Thu 10 Aug 2017 06:23:10 PM UTC
Category: Octave Forge Package
Severity: 3 - Normal
Priority: 5 - Normal
Item Group: Incorrect Result
Status: None
Assigned to: None
Originator Name:
Originator Email:
Open/Closed: Open
Discussion Lock: Any
Release: 4.2.1
Operating System: Any
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Details:
Here is how to reproduce the behavior:
clear, close all
pkg load image
A = peaks ();
B = A ./ 100;
Armax = imregionalmax (A);
Brmax = imregionalmax (B);
sum_Armax = sum(Armax(:))
sum_Brmax = sum(Brmax(:))
sum_ABrmax_Matlab = 4
There are several problems with this:
* The output of imregionalmax (for float input images) depends on the absolute
size of the input. This should not happen.
* The output of imregionalmax is not the same as Matlab's output (which is
4).
This happens with current Octave (4.2.1) and image package release (2.6.1).
The underlying function imreconstruct seems to NOT be the problem. Because
when I run the Octave code of imregionalmax.m (at least the essential code
line) under Matlab (and thus use the Matlab implementation of imreconstruct),
then the wrong results (3 and 1) stay.
To me it seems that the current code of imregionalmax (i.e. "recon =
imreconstruct (img, img + 1)") is only ment to be applied to integer valued
input images.
Maybe a possibility to calculate the same thing for float input images would
be "recon = imreconstruct (img, img + eps (im))". This little change made the
result of the above script Matlab compatible for me (i.e. 4 in both cases, and
also the same index positions in Armax and Brmax as in Matlab).
_______________________________________________________
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<http://savannah.gnu.org/bugs/?51724>
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- [Octave-bug-tracker] [bug #51724] image package: imregionalmax misbehaves on float images,
Hartmut <=
- [Octave-bug-tracker] [bug #51724] image package: imregionalmax misbehaves on float images, Hartmut, 2017/08/10
- [Octave-bug-tracker] [bug #51724] [octave forge] (image) imregionalmax misbehaves on float images, John W. Eaton, 2017/08/11
- [Octave-bug-tracker] [bug #51724] [octave forge] (image) imregionalmax misbehaves on float images, Avinoam Kalma, 2017/08/13
- [Octave-bug-tracker] [bug #51724] [octave forge] (image) imregionalmax misbehaves on float images, Avinoam Kalma, 2017/08/13
- [Octave-bug-tracker] [bug #51724] [octave forge] (image) imregionalmax misbehaves on float images, Avinoam Kalma, 2017/08/14
- [Octave-bug-tracker] [bug #51724] [octave forge] (image) imregionalmax misbehaves on float images, Hartmut, 2017/08/27
- [Octave-bug-tracker] [bug #51724] [octave forge] (image) imregionalmax misbehaves on float images, Hartmut, 2017/08/28
- [Octave-bug-tracker] [bug #51724] [octave forge] (image) imregionalmax misbehaves on float images, Avinoam Kalma, 2017/08/29
- [Octave-bug-tracker] [bug #51724] [octave forge] (image) imregionalmax misbehaves on float images, Avinoam Kalma, 2017/08/29
- [Octave-bug-tracker] [bug #51724] [octave forge] (image) imregionalmax misbehaves on float images, Hartmut, 2017/08/29