Today, I'm writing about how to create animated PNG (APNG) files, such as this one: I first wrote about APNG files last February. An APNG file is a valid PNG image file that uses file metadata in a... read more >>

Last time, I talked about the function impyramid and how I have been dissatisfied with it. (Confession: I designed it.) Today I want to present an alternative approach to creating a multiresolution... read more >>

Today I want to finish up my long-running discussion of Feret diameters. (Previous posts: 29-Sep-2017, 24-Oct-2017, 20-Feb-2018, and 16-Mar-2018.) Recall that the Feret diameter measures the... read more >>

Last time (if you can remember that long ago), I talked about how to find the maximum Feret diameter of a shape. The Feret diameter, sometimes called the caliper diameter, is illustrated by the diagram below. In a virtual sense, place the object to be measured inside the jaws of a caliper, with the caliper oriented at a specified angle. Close the jaws tightly on the object while maintaining that angle. The distance between the jaws is the Feret diameter at that angle.... read more >>

Last time, I wrote about finding the maximum Feret diameter for an object in a binary image, ending up with this figure: I had computed the convex hull of all the pixel corners, and then I computed... read more >>

Today I'll try to wrap up my discussion about how aliasing affects image resizing and about how the imresize function tries to prevent it. (This is called antialiasing.) Let me show you where we are... read more >>

ContentsConstruct the signalExploring the "spread" around the peakMoving the sinusoid frequency to line up with a binUsing a longer signalSummaryNote: I really didn't expect to be writing about the... read more >>

Today I'm wrapping up my analysis of the results of my Cody problem on eliminating unnecessary polygon vertices.... read more >>

On my list of potential blog topics today I saw just this cryptic item labeled dftmtx. Hmm, the MATLAB dftmtx function. But have I written about this function before? I better double-check by... read more >>

I've been intending to mention a new function bwconvhull that was introduced in the Image Processing Toolbox last spring in the R2011a release. Now that R2011b is out, I figure I better... read more >>