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[Octave-bug-tracker] [bug #44396] bwmorph shrink does not preserve Euler
From: |
Cory Bloor |
Subject: |
[Octave-bug-tracker] [bug #44396] bwmorph shrink does not preserve Euler number |
Date: |
Sun, 01 Mar 2015 11:03:34 +0000 |
User-agent: |
Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:36.0) Gecko/20100101 Firefox/36.0 |
URL:
<http://savannah.gnu.org/bugs/?44396>
Summary: bwmorph shrink does not preserve Euler number
Project: GNU Octave
Submitted by: cbloor
Submitted on: Sun 01 Mar 2015 11:03:33 AM GMT
Category: Octave Forge Package
Severity: 3 - Normal
Priority: 5 - Normal
Item Group: Incorrect Result
Status: None
Assigned to: None
Originator Name: Cory Bloor
Originator Email:
Open/Closed: Open
Discussion Lock: Any
Release: 3.8.1
Operating System: GNU/Linux
_______________________________________________________
Details:
The documentation for bwmorph shrink states that it preserves the Euler
number, but I've found a case where that doesn't seem to be true.
octave:1> version
ans = 3.8.1
octave:2> in= [0, 0, 0, 1, 0;
> 1, 1, 1, 1, 0;
> 0, 0, 1, 1, 0;
> 0, 0, 1, 1, 0;
> 0, 0, 0, 1, 0]
in =
0 0 0 1 0
1 1 1 1 0
0 0 1 1 0
0 0 1 1 0
0 0 0 1 0
octave:3> out=bwmorph(in, 'shrink')
out =
0 0 0 0 0
0 1 1 1 0
0 0 0 0 0
0 0 0 1 0
0 0 0 1 0
octave:4> bweuler(in)
ans = 1
octave:5> bweuler(out)
ans = 2
I discovered this while implementing shrink in C++ from the book "Digital
Image Processing" by William K. Pratt. I was surprised by my result, so I
checked it against Octave's result. I was then very surprised when Octave's
result matched mine. I think we both might be making the same mistake.
_______________________________________________________
Reply to this item at:
<http://savannah.gnu.org/bugs/?44396>
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- [Octave-bug-tracker] [bug #44396] bwmorph shrink does not preserve Euler number,
Cory Bloor <=
- [Octave-bug-tracker] [bug #44396] image package: bwmorph shrink does not preserve Euler number, Carnë Draug, 2015/03/01
- [Octave-bug-tracker] [bug #44396] image package: bwmorph shrink does not preserve Euler number, Avinoam Kalma, 2015/03/01
- [Octave-bug-tracker] [bug #44396] image package: bwmorph shrink does not preserve Euler number, Carnë Draug, 2015/03/01
- [Octave-bug-tracker] [bug #44396] image package: bwmorph shrink does not preserve Euler number, Avinoam Kalma, 2015/03/01
- [Octave-bug-tracker] [bug #44396] image package: bwmorph shrink does not preserve Euler number, Cory Bloor, 2015/03/01
- [Octave-bug-tracker] [bug #44396] image package: bwmorph shrink does not preserve Euler number, Carnë Draug, 2015/03/02
- [Octave-bug-tracker] [bug #44396] image package: bwmorph shrink does not preserve Euler number, Cory Bloor, 2015/03/02