how to find magnitude of image of size 256x384

please tell me how to find and plot the magnitude of the image & how to quantize the output after finding it's magnitude

[Image Analyst]

I've been doing imaging over 30 years and I have no idea what this means.

[ganesh s]

sir, i have taken the color image of size 256x384. then i have converted it in to gray image (using rgb2gray).then i have find it's Fourier transform.then i need to find the magnitude of the image(because after finding FFT of image we get the complex values)for the image quantization.

I know how to find the magnitude of image(using abs command)but i don't know how to do image quantization on the basis of magnitude values of image (because it's contain exponential values ) & i want to know how to quantize the gray image

[Image Analyst]

I still have no idea what you said. The gray scale image is already quantized. Do you want to quantize it in intensity differently? Like into fewer gray levels?

Answer 1

[Walter Roberson]

Finding the magnitude of the discrete Fourier transform does not calculate the magnitude of the image: it only finds the magnitude of the frequency components. If you were to quantize the frequency components and then ifft() to get back to an image, I suspect the result would be pretty messy.

[ganesh s]

@ walter Roberson :thanks sir