Comments on: POLY2MASK and ROIPOLY - Part 1 http://blogs.mathworks.com/steve/2006/12/05/poly2mask-and-roipoly-part-1/ 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> Mon, 23 Nov 2009 00:00:29 +0000 http://wordpress.org/?v=2.3.1 By: Steve http://blogs.mathworks.com/steve/2006/12/05/poly2mask-and-roipoly-part-1/#comment-21928 Steve Wed, 01 Jul 2009 13:12:02 +0000 http://blogs.mathworks.com/steve/2006/12/05/poly2mask-and-roipoly-part-1/#comment-21928 MoHDa—It might be possible. You'll need to use one of the options that produces closed edge contours, or work out some way of closing them yourself. MoHDa—It might be possible. You’ll need to use one of the options that produces closed edge contours, or work out some way of closing them yourself.

]]> By: MoHDa http://blogs.mathworks.com/steve/2006/12/05/poly2mask-and-roipoly-part-1/#comment-21927 MoHDa Tue, 30 Jun 2009 20:09:41 +0000 http://blogs.mathworks.com/steve/2006/12/05/poly2mask-and-roipoly-part-1/#comment-21927 I have one question about the ROIPOLY: I have an image with stripes, I use the "edge" command for finding the edges, is it possible to use the output of edge as input to ROIPOLY and just extract the information that is included in the edges lines? I have one question about the ROIPOLY:

I have an image with stripes, I use the “edge” command for finding the edges, is it possible to use the output of edge as input to ROIPOLY and just extract the information that is included in the edges lines?

]]> By: Steve http://blogs.mathworks.com/steve/2006/12/05/poly2mask-and-roipoly-part-1/#comment-10588 Steve Tue, 25 Sep 2007 13:18:23 +0000 http://blogs.mathworks.com/steve/2006/12/05/poly2mask-and-roipoly-part-1/#comment-10588 Sridharan—Use your polygon vertices to create a patch object that is superimposed over the image. Then you can adjust the transparency of the patch. Sridharan—Use your polygon vertices to create a patch object that is superimposed over the image. Then you can adjust the transparency of the patch.

]]> By: Sridharan Kamalakannan http://blogs.mathworks.com/steve/2006/12/05/poly2mask-and-roipoly-part-1/#comment-9820 Sridharan Kamalakannan Wed, 19 Sep 2007 04:05:17 +0000 http://blogs.mathworks.com/steve/2006/12/05/poly2mask-and-roipoly-part-1/#comment-9820 Hi Steve, I have a polygon which i coverted to a mask by using poly2mask command. Now i have to color the mask by using patch, i.e. i want to superimpose a color mask on an image such that I can adjust the transparency of the mask. In short I would like to know if there is some command to fill specific pixels with a color such that its transparency can be adjusted. Hi Steve,

I have a polygon which i coverted to a mask by using poly2mask command. Now i have to color the mask by using patch, i.e. i want to superimpose a color mask on an image such that I can adjust the transparency of the mask.

In short I would like to know if there is some command to fill specific pixels with a color such that its transparency can be adjusted.

]]> By: Steve http://blogs.mathworks.com/steve/2006/12/05/poly2mask-and-roipoly-part-1/#comment-6626 Steve Wed, 28 Mar 2007 19:58:03 +0000 http://blogs.mathworks.com/steve/2006/12/05/poly2mask-and-roipoly-part-1/#comment-6626 Olivier - I don't have a polygon vertex reduction function to offer you, but I'll add it to my list of possible blog topics. Fortunately, for the output of bwboundaries or bwtraceboundary, the vertices all lie on a regular axes-oriented grid, so there are no numerical problems with determining colinearity. I think you might be able to eliminate vertices efficiently in iterations in which you alternate between considering odd-numbered and even-numbered vertices. Olivier - I don’t have a polygon vertex reduction function to offer you, but I’ll add it to my list of possible blog topics. Fortunately, for the output of bwboundaries or bwtraceboundary, the vertices all lie on a regular axes-oriented grid, so there are no numerical problems with determining colinearity. I think you might be able to eliminate vertices efficiently in iterations in which you alternate between considering odd-numbered and even-numbered vertices.

]]> By: Olivier http://blogs.mathworks.com/steve/2006/12/05/poly2mask-and-roipoly-part-1/#comment-6595 Olivier Wed, 21 Mar 2007 16:11:55 +0000 http://blogs.mathworks.com/steve/2006/12/05/poly2mask-and-roipoly-part-1/#comment-6595 Steve, Thanks for the advice, but I think I need a vertex reduction script now. Any advice on that? Thanks again, Olivier. Steve,

Thanks for the advice, but I think I need a vertex reduction script now. Any advice on that?

Thanks again,

Olivier.

]]> By: Steve http://blogs.mathworks.com/steve/2006/12/05/poly2mask-and-roipoly-part-1/#comment-6593 Steve Wed, 21 Mar 2007 12:13:50 +0000 http://blogs.mathworks.com/steve/2006/12/05/poly2mask-and-roipoly-part-1/#comment-6593 Olivier - look at <tt>bwboundaries</tt> and <tt>bwtraceboundary</tt> in the Image Processing Toolbox. Olivier - look at bwboundaries and bwtraceboundary in the Image Processing Toolbox.

]]> By: Olivier http://blogs.mathworks.com/steve/2006/12/05/poly2mask-and-roipoly-part-1/#comment-6592 Olivier Wed, 21 Mar 2007 10:38:15 +0000 http://blogs.mathworks.com/steve/2006/12/05/poly2mask-and-roipoly-part-1/#comment-6592 Dear Steve, I am actually looking for an algorithm that does the reverse of this script; a mask2poly so to speak. So, the input is a mask and the output a number of vertices. Would you know if there is any script in Matlab that does this? Regards, Olivier. Dear Steve,

I am actually looking for an algorithm that does the reverse of this script; a mask2poly so to speak. So, the input is a mask and the output a number of vertices. Would you know if there is any script in Matlab that does this?

Regards,

Olivier.

]]> By: Steve http://blogs.mathworks.com/steve/2006/12/05/poly2mask-and-roipoly-part-1/#comment-6402 Steve Fri, 08 Dec 2006 14:36:27 +0000 http://blogs.mathworks.com/steve/2006/12/05/poly2mask-and-roipoly-part-1/#comment-6402 Andy - The output values are computed as the nearest distance between the element center and the idealized line segment. I couldn't find this anywhere in the doc, so we'll make a note to add this information in a future release. Andy - The output values are computed as the nearest distance between the element center and the idealized line segment. I couldn’t find this anywhere in the doc, so we’ll make a note to add this information in a future release.

]]> By: Andy http://blogs.mathworks.com/steve/2006/12/05/poly2mask-and-roipoly-part-1/#comment-6389 Andy Thu, 07 Dec 2006 06:31:38 +0000 http://blogs.mathworks.com/steve/2006/12/05/poly2mask-and-roipoly-part-1/#comment-6389 Dear Steve, I have a question smiliar to deciding the mask values along the edge. I hope it's okay to ask here. How is the motion blur (obtained by fspecial('motion',len,theta)) actually defined? I couldn't find the formula in the Uers' Guide. Thanks. Andy Dear Steve,

I have a question smiliar to deciding the mask values along the edge. I hope it’s okay to ask here. How is the motion blur (obtained by fspecial(’motion’,len,theta)) actually defined? I couldn’t find the formula in the Uers’ Guide. Thanks.

Andy

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