The functions bwlabel and regionprops are very useful for measuring the properties of shapes in a binary image. There are documentation examples and product demos showing how to do this,... read more >>

About twelve years ago, I was implementing the algorithm that became roifill in the Image Processing Toolbox. In this algorithm, a specified set of pixels is replaced (or filled in) such that... read more >>

So far in this series I've talked about calculating pixel flow directions and handling plateaus, but I haven't yet discussed the actual upslope area calculation. The Tarboton paper... read more >>

In March 2006 I wrote about how to overlay a specified color onto specified pixels of a grayscale or RGB image. I put a utility function (imoverlay) for performing this... read more >>

A few weeks ago I promised a series on developing a MATLAB algorithm to compute upslope area. Now I'm ready to begin that project in earnest. First, though, I'd like to comment on the... read more >>

Back in October I introduced the concept of filter separability. A two-dimensional filter s is said to be separable if it can be written as the convolution of two one-dimensional filters v and... read more >>

A MATLAB user asked me how to determine which image pixels had local maxima that weren't unique. My answer involves a creative use of ordfilt2. Let's review first the concept... read more >>