Comments on: Dilation algorithms—structuring element decomposition http://blogs.mathworks.com/steve/2008/09/17/dilation-structuring-element-decomposition/ Steve Eddins manages the Image & Geospatial development team at The MathWorks and coauthored Digital Image Processing Using MATLAB. He writes here about image processing concepts, algorithm implementations, and MATLAB. Sat, 11 Feb 2012 18:27:50 +0000 hourly 1 http://wordpress.org/?v=3.2.1 By: Steve http://blogs.mathworks.com/steve/2008/09/17/dilation-structuring-element-decomposition/#comment-23778 Steve Mon, 13 Dec 2010 13:13:55 +0000 http://blogs.mathworks.com/steve/2008/09/17/dilation-structuring-element-decomposition/#comment-23778 Mohammed—What do you mean by "scalable structure element"? Mohammed—What do you mean by “scalable structure element”?

]]> By: Mohammed Aqlan http://blogs.mathworks.com/steve/2008/09/17/dilation-structuring-element-decomposition/#comment-23774 Mohammed Aqlan Sat, 11 Dec 2010 12:27:55 +0000 http://blogs.mathworks.com/steve/2008/09/17/dilation-structuring-element-decomposition/#comment-23774 Hi, I got good points from your explanation but I have one question for you how I can get a scalable structure element,,,, I tried but I could not get it to use it in making a local enhancement of gray images,,,, Hi,
I got good points from your explanation but I have one question for you how I can get a scalable structure element,,,, I tried but I could not get it to use it in making a local enhancement of gray images,,,,

]]> By: Steve http://blogs.mathworks.com/steve/2008/09/17/dilation-structuring-element-decomposition/#comment-22176 Steve Mon, 05 Oct 2009 14:48:39 +0000 http://blogs.mathworks.com/steve/2008/09/17/dilation-structuring-element-decomposition/#comment-22176 Anne—That's a very good point. The performance of implementations of binary dilation and erosion can be data-dependent. When we do performance benchmarking of binary dilation, we usually use a couple of images: one with just a few foreground pixels and one with many foreground pixels. It's difficult to write a binary dilation routine that performs equally well for all kinds of input images. For grayscale dilation and erosion, though, the performance is not data dependent and structuring element decomposition is a clear win. Anne—That’s a very good point. The performance of implementations of binary dilation and erosion can be data-dependent. When we do performance benchmarking of binary dilation, we usually use a couple of images: one with just a few foreground pixels and one with many foreground pixels. It’s difficult to write a binary dilation routine that performs equally well for all kinds of input images.

For grayscale dilation and erosion, though, the performance is not data dependent and structuring element decomposition is a clear win.

]]> By: Anne http://blogs.mathworks.com/steve/2008/09/17/dilation-structuring-element-decomposition/#comment-22156 Anne Wed, 23 Sep 2009 21:21:41 +0000 http://blogs.mathworks.com/steve/2008/09/17/dilation-structuring-element-decomposition/#comment-22156 Hi Steve, It seems to me that the time savings you get by decomposing the structuring element depend a bit on the initial volume. In the case of a mostly empty volume with only a small percentage of non-zero voxels, I think decomposition could actually cost more time! For the limiting case, say we have a 3D volume with only 1 nonzero voxel which we are dilating with a 5x5x5 structuring element. In the case of no decomposition, 125 comparison are made. However, if you decompose the structuring element into 3 linear elements, you have to do 1*5 (first step) + 5*5 (second step) + 25*5 (third step) = 155 comparisons. Is my logic correct here? Thanks, Anne Hi Steve,

It seems to me that the time savings you get by decomposing the structuring element depend a bit on the initial volume. In the case of a mostly empty volume with only a small percentage of non-zero voxels, I think decomposition could actually cost more time! For the limiting case, say we have a 3D volume with only 1 nonzero voxel which we are dilating with a 5x5x5 structuring element. In the case of no decomposition, 125 comparison are made. However, if you decompose the structuring element into 3 linear elements, you have to do 1*5 (first step) + 5*5 (second step) + 25*5 (third step) = 155 comparisons. Is my logic correct here?

Thanks,
Anne

]]> By: Steve http://blogs.mathworks.com/steve/2008/09/17/dilation-structuring-element-decomposition/#comment-21593 Steve Fri, 20 Mar 2009 12:33:24 +0000 http://blogs.mathworks.com/steve/2008/09/17/dilation-structuring-element-decomposition/#comment-21593 Lala—Dilation and erosion are dual operators. There is relatively little difference between them in terms of algorithms and implementation. Everything I've written about dilation applies to erosion, so I have no plans to write anything further that's specific to erosion. Closing is just dilation followed by erosion. Lala—Dilation and erosion are dual operators. There is relatively little difference between them in terms of algorithms and implementation. Everything I’ve written about dilation applies to erosion, so I have no plans to write anything further that’s specific to erosion. Closing is just dilation followed by erosion.

]]> By: lala http://blogs.mathworks.com/steve/2008/09/17/dilation-structuring-element-decomposition/#comment-21592 lala Thu, 19 Mar 2009 21:47:11 +0000 http://blogs.mathworks.com/steve/2008/09/17/dilation-structuring-element-decomposition/#comment-21592 Hi Steve, I'm searching for algorithm concepts behind the implementation of erosion and closing in the Image Processing Toolbox in Matlab. Looks like you haven't update on this yet. Can you please give me a brief detail on this? Thank you very much. ~Lala Hi Steve,

I’m searching for algorithm concepts behind the implementation of erosion and closing in the Image Processing Toolbox in Matlab. Looks like you haven’t update on this yet. Can you please give me a brief detail on this? Thank you very much.

~Lala

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