Comments on: Nonflat grayscale dilation and erosion http://blogs.mathworks.com/steve/2006/10/23/nonflat-grayscale-dilation-and-erosion/ Steve Eddins manages the Image & Geospatial development team at <a href="http://www.mathworks.com/">The MathWorks</a> and coauthored <a href="http://www.mathworks.com/support/books/book5291.html?category=-1&language=-1">Digital Image Processing Using MATLAB</a>. He writes here about image processing concepts, algorithm implementations, and MATLAB.<br><br><img> Sun, 22 Nov 2009 23:25:22 +0000 http://wordpress.org/?v=2.3.1 By: Steve http://blogs.mathworks.com/steve/2006/10/23/nonflat-grayscale-dilation-and-erosion/#comment-22319 Steve Wed, 11 Nov 2009 12:18:34 +0000 http://blogs.mathworks.com/steve/2006/10/23/nonflat-grayscale-dilation-and-erosion/#comment-22319 Fredric—Use the <tt>'ball'</tt> with <tt>strel</tt>. You can also construct a structuring element of arbitrary shape by specifying the domain (nhood) and height values yourself. Fredric—Use the ‘ball’ with strel. You can also construct a structuring element of arbitrary shape by specifying the domain (nhood) and height values yourself.

]]> By: Fredric http://blogs.mathworks.com/steve/2006/10/23/nonflat-grayscale-dilation-and-erosion/#comment-22318 Fredric Wed, 11 Nov 2009 09:44:46 +0000 http://blogs.mathworks.com/steve/2006/10/23/nonflat-grayscale-dilation-and-erosion/#comment-22318 Is there any hemispheric structuring element coding in MATLAB? Is there any hemispheric structuring element coding
in MATLAB?

]]> By: Steve http://blogs.mathworks.com/steve/2006/10/23/nonflat-grayscale-dilation-and-erosion/#comment-22301 Steve Fri, 06 Nov 2009 17:23:40 +0000 http://blogs.mathworks.com/steve/2006/10/23/nonflat-grayscale-dilation-and-erosion/#comment-22301 Kezia—Try <tt>imrotate</tt>. Kezia—Try imrotate.

]]> By: kezia http://blogs.mathworks.com/steve/2006/10/23/nonflat-grayscale-dilation-and-erosion/#comment-22299 kezia Fri, 06 Nov 2009 15:56:31 +0000 http://blogs.mathworks.com/steve/2006/10/23/nonflat-grayscale-dilation-and-erosion/#comment-22299 steve, how to perform rotation of structuring element by 15 degrees. kindly answer my question. thank u kezia joseph steve,
how to perform rotation of structuring element by 15 degrees.
kindly answer my question.
thank u
kezia joseph

]]> By: Steve http://blogs.mathworks.com/steve/2006/10/23/nonflat-grayscale-dilation-and-erosion/#comment-21757 Steve Wed, 13 May 2009 12:18:31 +0000 http://blogs.mathworks.com/steve/2006/10/23/nonflat-grayscale-dilation-and-erosion/#comment-21757 Christina—I do not understand why you are using the HEIGHT argument at all. NHOOD controls the shape of the structuring element; make that 3-D. Your threshold value will have to be applied as a separate step; erosion does not do that. Christina—I do not understand why you are using the HEIGHT argument at all. NHOOD controls the shape of the structuring element; make that 3-D. Your threshold value will have to be applied as a separate step; erosion does not do that.

]]> By: Christina http://blogs.mathworks.com/steve/2006/10/23/nonflat-grayscale-dilation-and-erosion/#comment-21754 Christina Tue, 12 May 2009 14:04:16 +0000 http://blogs.mathworks.com/steve/2006/10/23/nonflat-grayscale-dilation-and-erosion/#comment-21754 Hi, thanks for the answer, but how should I modify the HEIGHT to make it 3d? I have a Volume and I want to 'filter' or take out all structures whos values that are higher than a certain threshold and that are connected in the origin/center over 3 slices. Is it correct than, if I use this 3D strel? Thanks so much, Christina Hi, thanks for the answer, but how should I modify the HEIGHT to make it 3d?
I have a Volume and I want to ‘filter’ or take out all structures whos values that are higher than a certain threshold and that are connected in the origin/center over 3 slices. Is it correct than, if I use this 3D strel?
Thanks so much, Christina

]]> By: Steve http://blogs.mathworks.com/steve/2006/10/23/nonflat-grayscale-dilation-and-erosion/#comment-21753 Steve Tue, 12 May 2009 13:42:26 +0000 http://blogs.mathworks.com/steve/2006/10/23/nonflat-grayscale-dilation-and-erosion/#comment-21753 Christina—You have used a two-dimensional structuring element neighborhood (NHOOD), so you're only going to get within-plane effects. Use a three-dimensional one instead. Also, I doubt that you need the HEIGHT argument. Christina—You have used a two-dimensional structuring element neighborhood (NHOOD), so you’re only going to get within-plane effects. Use a three-dimensional one instead. Also, I doubt that you need the HEIGHT argument.

]]> By: Christina http://blogs.mathworks.com/steve/2006/10/23/nonflat-grayscale-dilation-and-erosion/#comment-21750 Christina Tue, 12 May 2009 09:33:11 +0000 http://blogs.mathworks.com/steve/2006/10/23/nonflat-grayscale-dilation-and-erosion/#comment-21750 Hi Steve, I have the following problem: I have a 256*256*20 Volume (MRImage) and I want to use strel to cluster connected elements. It works perfect if I use it in 2-D like se = strel('diamond',1); area = imerode(area,se); what I want is to cluster the actual plane with the plane before and the plane behind. If I use NHOOD=[0 1 0; 1 1 1 ; 0 1 0]; HEIGHT=[0 0 0 ; 0 1 0; 0 0 0]; se=strel(NHOOD,HEIGHT); Volume2=imerode(Volume,se); nothing happens. Where is my mistake? Thanks in advance, Christina Hi Steve, I have the following problem: I have a 256*256*20 Volume (MRImage) and I want to use strel to cluster connected elements. It works perfect if I use it in 2-D like

se = strel(’diamond’,1);
area = imerode(area,se);

what I want is to cluster the actual plane with the plane before and the plane behind.

If I use
NHOOD=[0 1 0; 1 1 1 ; 0 1 0];
HEIGHT=[0 0 0 ; 0 1 0; 0 0 0];
se=strel(NHOOD,HEIGHT);
Volume2=imerode(Volume,se);
nothing happens. Where is my mistake?
Thanks in advance, Christina

]]> By: clcclcclc http://blogs.mathworks.com/steve/2006/10/23/nonflat-grayscale-dilation-and-erosion/#comment-20666 clcclcclc Tue, 29 Apr 2008 12:36:49 +0000 http://blogs.mathworks.com/steve/2006/10/23/nonflat-grayscale-dilation-and-erosion/#comment-20666 Oh,thank you very much.Recently I saw a paper named "FACE DETECTION IN COLOR IMAGES" by Rein-Lien Hsu§, Mohamed Abdel-Mottaleb*, and Anil K. Jain §,in which mentioned that "In our eye detection algorithm, the greyscale dilation and erosion using hemispheric structuring elements at an estimated scale are applied independently to construct EyeMap in the luma". Now I know the algorithm,but I don't know the structure to be used. I am a Chinese student,thank you again for your answer Oh,thank you very much.Recently I saw a paper named
“FACE DETECTION IN COLOR IMAGES” by Rein-Lien Hsu§, Mohamed Abdel-Mottaleb*, and Anil K. Jain §,in which mentioned that “In our eye detection algorithm, the greyscale dilation and erosion using hemispheric structuring elements at an estimated scale are applied independently to construct EyeMap in the luma”.
Now I know the algorithm,but I don’t know the structure to be used.
I am a Chinese student,thank you again for your answer

]]> By: Steve http://blogs.mathworks.com/steve/2006/10/23/nonflat-grayscale-dilation-and-erosion/#comment-20665 Steve Tue, 29 Apr 2008 11:32:23 +0000 http://blogs.mathworks.com/steve/2006/10/23/nonflat-grayscale-dilation-and-erosion/#comment-20665 clcclcclc—That's an interesting name that you have. How do you pronounce it? I haven't seen the term <em>scaled hemispheric element</em> before, but I'd guess that it's the kind of structuring element returned by <tt>strel('ball', ...)</tt>. See the <a href="http://www.mathworks.com/access/helpdesk/help/toolbox/images/strel.html" rel="nofollow">strel doc</a> for more information. clcclcclc—That’s an interesting name that you have. How do you pronounce it?

I haven’t seen the term scaled hemispheric element before, but I’d guess that it’s the kind of structuring element returned by strel(’ball’, …).

See the strel doc for more information.

]]>