Updated: 2012-01-26 04:40:47
This week I came across some files I wrote about 16 years ago to compute Hilbert curves. A Hilbert curve is a type of fractal curve; here is a sample: I can't remember why I was working on this. Possibly I was anticipating that 16 years in the future, during an unusually mild New England [...]
Updated: 2012-01-13 20:50:33
Much of the information I posted in this blog years ago is still useful today. Image processing theory hasn't been completely been overturned since then, and I'm still talking about MATLAB after all. For the benefit of readers who have joined the party more recently, I will occasionally recap the useful bits that I posted [...]
Updated: 2011-12-28 00:00:45
Blog reader Mike posed the following question recently: If you have a bunch of point locations (for example, object centroids), how you make a binary image containing just those points? For example, consider this image:bw = imread('text.png'); imshow(bw, 'InitialMagnification', 200) How can we make an image like this, where the dots are located at the [...]
Updated: 2011-12-23 00:00:31
Blog reader Asadullah posted the following question last week on my old post about batch processing: I am trying to process some images by following the MATLAB demo. After getting the names of files when I try to see any of the files then it gives the error. The detail is as follows: >> fileFolder [...]
Updated: 2011-12-21 13:20:18
For the past several weeks I've been writing about shortest-path problems in image processing: finding the shortest path between two points in an image, with and without constraints. Applications included the practical (path finding in a skeleton image) and fun (maze solving). Along the way, I've described: the basic idea of finding shortest paths by [...]
Updated: 2011-12-13 07:00:45
In this post in the Exploring shortest paths series, I make things a little more complicated (and interesting) by adding constraints to the shortest path problem. Last time, I showed this example of finding the shortest paths between the "T" and the sideways "s" in this image: url = 'http://blogs.mathworks.com/images/steve/2011/two-letters-cropped.png'; bw = imread(url);And this was [...]
Updated: 2011-12-06 07:00:11
In my previous posts on Exploring shortest paths (November 1, November 26, and December 3), I have noted several times that there isn't a unique shortest path (in general) between one object and another in a binary image. To illustrate, here's a recap of the 'quasi-euclidean' example from last time. bw = logical([ ... 0 [...]
Updated: 2011-12-02 18:00:55
In part 2 of Exploring shortest paths, I noted a problem with using the 'quasi-euclidean' distance transform to find the shortest paths between two objects in a binary image. Specifically, our algorithm resulted in a big, unfilled gap between the two objects. bw = logical([ ... 0 0 0 0 0 0 0 0 1 [...]