I applied fft followed by log polar mapping on an image but when i applied inverse log polar mapping followed by inverse fft, i'm not getting the original image back .. what should be done to bring back the original image.?

i=imread('lena.jpg'); [r c]=size(i); im=fft2(i); rmin=1; rmax=c; xc=r/2; yc=c/2; lpm=logsample(im,rmin,rmax,xc,yc,r,c); ilpm=logsampleback(lpm,rmin,rmax); ifft=ifft2(ilpm); imshow(ifft);