Hi all, I am a beginner in matlab and i seriously need your help. MY PROBLEM: I have a grayscale image(1024 X 1280) of a pyrovalve(a valve used in rocket engines, looks like a small piston cylinder arrangement). I was asked to do fourier analysis(2D) on this image. For that i took FFT2 of the image. I can get the absolute frequency values. I have to make a 3D plot of the frequency magnitude. When i used mesh(abs(fft2(I))), i can see a 3D plot, which is flat. The x, y axes taking the no. of pixels and z axes taking the magnitude. But i need to get a Sombrero plot(a mexican hat). How can i get that plot? And i have a question regarding the "Spatial frequency". How can i calculate spatial frequency from pixels?. I believe, i need to take the frequency on x and y axes and magnitude of frquency on z axes to get a sombrero plot. Does my image really produce a sombrero plot or not? Can anyone rectify my problem and explain me clearly. Waiting for a reply, shashi

# Need some help for FFT2 of an Image

Started by ●July 13, 2008