One the measurements provided by regionprops is 'Centroid'. Here's an example of labeling binary objects, computing the centroid of each object, and plotting the centroid location on top... read more >>

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 >>

Didja know? You can fill holes, or pits, in grayscale images by using the Image Processing Toolbox function imfill. The other day I was rereading the Tarboton paper on upslope area,... read more >>

[NOTE: After I originally wrote this post about handling plateaus, I discovered problems with the method, so I am no longer using it. I revisited the plateau issue in a later post. -SE] ... read more >>

Last week I wrote about a possible modification to poly2mask that would estimate how much of each pixel is contained within a polygon. The idea was to use a regular 5-by-5 subgrid and ... read more >>

Several people have asked me recently how to plot some kind of shape on top of an image, so I thought I'd show the basic technique here. Essentially, you display the image, then call hold on,... read more >>

This is the final post in a series discussing the algorithm underlying Image Processing Toolbox functions poly2mask and roipoly. (See Part 1 and Part 2.) There are several desirable... read more >>

I'm familiar with two basic ways to determine whether a point is inside a polygon. The first is to compute the winding number, which is the number of times that a closed curve encircles the... read more >>

This is the first of several blogs about the algorithm behind poly2mask and roipoly. poly2mask takes a set of polygon vertices and produces a binary mask image. The binary mask has 1s for... read more >>

Reader JP asked me about my recent blog post on the Hough transform. Specifically, she wanted to know exactly how the rho-theta coordinate system was defined. When I answered her question, ... read more >>