Comments on: bwselect http://blogs.mathworks.com/steve/2007/10/26/bwselect/ 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. Wed, 01 Feb 2012 13:58:45 +0000 hourly 1 http://wordpress.org/?v=3.2.1 By: Steve http://blogs.mathworks.com/steve/2007/10/26/bwselect/#comment-24126 Steve Tue, 26 Apr 2011 12:02:14 +0000 http://blogs.mathworks.com/steve/2007/10/26/bwselect/#comment-24126 Denis—Use <a href="http://www.mathworks.com/help/toolbox/images/ref/regionprops.html" rel="nofollow">regionprops</a> with the 'Area' measurement. Denis—Use regionprops with the ‘Area’ measurement.

]]> By: denis http://blogs.mathworks.com/steve/2007/10/26/bwselect/#comment-24125 denis Mon, 25 Apr 2011 11:04:46 +0000 http://blogs.mathworks.com/steve/2007/10/26/bwselect/#comment-24125 Hi Steve, I need to select the biggest object in a b&w picture.So is there a possible way in matlab to realise it without indicate particular pixel values? Hi Steve,
I need to select the biggest object in a b&w picture.So is there a possible way in matlab to realise it without indicate particular pixel values?

]]> By: Steve http://blogs.mathworks.com/steve/2007/10/26/bwselect/#comment-21599 Steve Sun, 22 Mar 2009 22:30:25 +0000 http://blogs.mathworks.com/steve/2007/10/26/bwselect/#comment-21599 Tarik—Use <tt>find</tt> to get the indices of the select object. Set the image elements at those location to zero. Offset the locations by the desired amount, and then set the image elements at the offset locations to be 1. Tarik—Use find to get the indices of the select object. Set the image elements at those location to zero. Offset the locations by the desired amount, and then set the image elements at the offset locations to be 1.

]]> By: Tarik http://blogs.mathworks.com/steve/2007/10/26/bwselect/#comment-21595 Tarik Sat, 21 Mar 2009 21:31:50 +0000 http://blogs.mathworks.com/steve/2007/10/26/bwselect/#comment-21595 Please, if you can help me , how can I use bwselect function, to change the location of the object which we selected, for example,we want to give new coordinates for this object! is it possible? Please, if you can help me , how can I use bwselect function, to change the location of the object which we selected, for example,we want to give new coordinates for this object! is it possible?

]]> By: Steve http://blogs.mathworks.com/steve/2007/10/26/bwselect/#comment-21076 Steve Tue, 16 Sep 2008 11:58:02 +0000 http://blogs.mathworks.com/steve/2007/10/26/bwselect/#comment-21076 Pete—Thanks for the kind words. I can't think of a way to do what you suggest without getting into some custom GUI programming. See my <a href="http://blogs.mathworks.com/steve/matlab-gui-programming-resources/" rel="nofollow">GUI programming resources</a> page. Pete—Thanks for the kind words. I can’t think of a way to do what you suggest without getting into some custom GUI programming. See my GUI programming resources page.

]]> By: Pete http://blogs.mathworks.com/steve/2007/10/26/bwselect/#comment-21067 Pete Mon, 15 Sep 2008 18:00:38 +0000 http://blogs.mathworks.com/steve/2007/10/26/bwselect/#comment-21067 Hi Steve. I have just recently started working with the image processing toolbox. At the moment I am trying to write a program that allows a user to select 'fields' on images of ordnance survey maps. I have been using bwselect and the mouse to allow the user to click on regions of interest. It would be very useful if I was able to display each selected region as colored after each single mouse click, as opposed to after the double click when all selections have been made. Is there any simple way to do this without creating a more complex GUI, or without creating a loop where the number of selections is known in advance? Alternatively, can you suggest some other suitable method? Thanks - great blog by the way! Hi Steve. I have just recently started working with the image processing toolbox. At the moment I am trying to write a program that allows a user to select ‘fields’ on images of ordnance survey maps. I have been using bwselect and the mouse to allow the user to click on regions of interest. It would be very useful if I was able to display each selected region as colored after each single mouse click, as opposed to after the double click when all selections have been made. Is there any simple way to do this without creating a more complex GUI, or without creating a loop where the number of selections is known in advance? Alternatively, can you suggest some other suitable method? Thanks – great blog by the way!

]]> By: Steve http://blogs.mathworks.com/steve/2007/10/26/bwselect/#comment-20199 Steve Fri, 15 Feb 2008 13:28:46 +0000 http://blogs.mathworks.com/steve/2007/10/26/bwselect/#comment-20199 Utk—You could use the interactive <tt>bwselect</tt> syntax, which lets you use the mouse to define starting locations, or you could use <tt>impixelinfo</tt> to display pixel location information on the figure window as you move the mouse around. Utk—You could use the interactive bwselect syntax, which lets you use the mouse to define starting locations, or you could use impixelinfo to display pixel location information on the figure window as you move the mouse around.

]]> By: Utk http://blogs.mathworks.com/steve/2007/10/26/bwselect/#comment-20185 Utk Fri, 15 Feb 2008 00:17:18 +0000 http://blogs.mathworks.com/steve/2007/10/26/bwselect/#comment-20185 How do you go about guessing pixels fir the bwselect function. In the above example I downloaded the image and tried fiddling with the numbers and i couldnt see anything. How do you go about guessing pixels fir the bwselect function. In the above example I downloaded the image and tried fiddling with the numbers and i couldnt see anything.

]]> By: Steve http://blogs.mathworks.com/steve/2007/10/26/bwselect/#comment-19468 Steve Tue, 29 Jan 2008 01:34:50 +0000 http://blogs.mathworks.com/steve/2007/10/26/bwselect/#comment-19468 StevenB—The function <tt>normxcorr2</tt> doesn't support that behavior. You'll have to modify the function yourself. StevenB—The function normxcorr2 doesn’t support that behavior. You’ll have to modify the function yourself.

]]> By: StevenB http://blogs.mathworks.com/steve/2007/10/26/bwselect/#comment-19460 StevenB Mon, 28 Jan 2008 20:28:52 +0000 http://blogs.mathworks.com/steve/2007/10/26/bwselect/#comment-19460 I've been playing with normxcorr2, specifically the image registration example at http://www.mathworks.com/products/demos/image/cross_correlation/imreg.html. It says "The image sub_onion will be the template, and must be smaller than the image sub_peppers." But when you run the example, the matrix of outputs is huge. How can I make the function only compute the coefficients for the cases where the template fits within the image to which it is being registered. For example, if I have a 100 X 100 master image and a 90 X 80 subimage, I want only a (100-90)X(100-80) = 10 X 20 matrix of coefficients. How do I tell the function not to pad the edges? I’ve been playing with normxcorr2, specifically the image registration example at http://www.mathworks.com/products/demos/image/cross_correlation/imreg.html.

It says “The image sub_onion will be the template, and must be smaller than the image sub_peppers.”

But when you run the example, the matrix of outputs is huge. How can I make the function only compute the coefficients for the cases where the template fits within the image to which it is being registered.

For example, if I have a 100 X 100 master image and a 90 X 80 subimage, I want only a (100-90)X(100-80) = 10 X 20 matrix of coefficients. How do I tell the function not to pad the edges?

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