Hi, I had an image with 345x345 pixels. Afetr performing fft it becomes 512x512 pixels. why? I found fft of same image using matlab and it gives output image as size of original image 345x345 pixels. Also, the fft values for both are different. the maximum value of fft I get from matlab is 23 but from ImageJ it is 253. How come fft of same images could be so different? For matlab, the codes are
A=imread('1A.bmp');B=fft2(A);C=fftshift(B);D=log2(abs(C));figure; imshow(D,[]),colormap(jet),colorbar;

I am not sure how to upload image. I will find it and will upload the image.First post so please be generous.

Thanks in advance for help.

-Komal