Steve on Image Processing

Concepts, algorithms & MATLAB

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Frequency Samples for the Output of FFT2 1

Posted by Steve Eddins,

A MATLAB user recently contacted tech support with a question about the output of fft2. The user had a function, q(x,y), evaluated on an (x,y) grid. The grid evaluation produced a matrix that the user passed to fft2. The user's question: what are the spatial frequencies associated with the elements... read more >>

The Future of String Arrays in MATLAB

Posted by Steve Eddins,

At MathWorks, we almost never talk in detail about product features before they are released. That's why this week's Art of MATLAB blog caught my eye. Guest blogger Dave Bergstein describes in some detail how we expect support for string arrays to evolve in the future. If you do a lot of data analysis or text processing in MATLAB, it is worth your while to take a look at Dave's post.... read more >>

The Eight Queens Problem 2

Posted by Steve Eddins,

Today I want to tackle a classic algorithm puzzle known as the Eight Queens Problem. In this problem, your task is to arrange eight queens on a chessboard so that none of the queens is attacking any of the others. Here is one solution.... read more >>

Logical indexing 3

Posted by Steve Eddins,

One of my favorite aspects of MATLAB for image processing is how I can use a binary image to index directly into a grayscale image. The technique is called logical indexing, and I'm going to show you how it works today.... read more >>

Gaussian filtering with imgaussfilt 2

Posted by Steve Eddins,

With the R2015a release a couple of years ago, the Image Processing Toolbox added the function imgaussfilt. This function performs 2-D Gaussian filtering on images. It features a heuristic that automatically switches between a spatial-domain implementation and a frequency-domain implementation.... read more >>

Aliasing and image resizing – part 3 4

Posted by Steve Eddins,

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 going. Here is the zone plate image I showed last time.... read more >>

These postings are the author's and don't necessarily represent the opinions of MathWorks.