Last week I talked about the so-called Jähne test pattern and how I found a description of it in Practical Handbook on Image Processing for Scientific Applications, by Bernd Jähne, CRC... 続きを読む >>

A reader asked in a blog comment recently why a vertical line (or edge) shows up in the Fourier transform of an image as a horizontal line. I thought I would try to explain this using the... 続きを読む >>

One of the discrete-time Fourier transform properties that many people learn is that if a sequence is conjugate symmetric, , then the Fourier transform is real. Therefore it... 続きを読む >>

In my Fourier transform series I've been trying to address some of the common points of confusion surrounding this topic. For today's espisode I want to look at how to use the fft... 続きを読む >>

OysterEngineer (I love that name!) asked some interesting questions in response to my last Fourier transform post, which concerned the relationship between the discrete-time Fourier transform... 続きを読む >>

h1 { font-size:18pt; } h2.titlebg { font-size:13pt; } h3 { color:#4A4F55; padding:0px; margin:5px 0px 5px; font-family:Arial, Helvetica, sans-serif; font-size:11pt; font-weight:bold;... 続きを読む >>

Many of you were onto me immediately last week. I asked you to estimate the frequency of the sampled cosine signal below, and readers quickly chimed in to guess that this question was... 続きを読む >>

When I dipped my toe into the Fourier transform waters last week, the resulting comments and e-mail indicated there is a lot of interest in tutorial material and explanations. I'm willing, ... 続きを読む >>

I'd like to welcome back guest blogger Stan Reeves, professor of Electrical and Computer Engineering at Auburn University. Stan will be writing a few blogs here about image... 続きを読む >>

Since I originally posted my upslope toolbox to MATLAB Central back in August, I have heard from some experts about an issue related to NaNs in the DEM data. Specifically, some data sets... 続きを読む >>