Slithe

For a school project, I need to think up some (hopefully easy) ways to compress (and decompress) images. I have looked at JPEG's algorithm, but it seems like much too much work to implement. This is just an assignment, so I was trying to think of algorithms that would be easier to implement in Matlab. Lately, I have been trying to compress a grayscale image by transforming it into frequency space with a Fourier Transform. Then I would examine each value of the transformed matrix and, if the value was small enough, I would just set it zero. I would then use run-length-encoding to pack all the zeroes. However, when I decoded (i.e. unpacked and transformed back to pixel space) the image, pretty much all the values were zero (i.e. the image was all black); however, most values in frequency space were not zero. What am I doing wrong? Here is my Matlab code. It takes as input a 3-d matrix that stores red green and blue values. function out = FFTCOMPRESS( in ) x = length(in(1,)/3 y = length(in(:,1)) fr = fft2(in(:,:,1)); fg = fft2(in(:,:,2)); fb = fft2(in(:,:,3)); myout = zeros(1, 5+4*y*x*3); myout(1) = x; myout(2) = y; myout(3) = 6; for ii=1:y, for jj=1:x, if fr(ii,jj)<10 fr(ii,jj)=0; end if fg(ii,jj)<10 fg(ii,jj)=0; end if fb(ii,jj)<10 fb(ii,jj)=0; end end end n = 6 nz = 0 for jj=1:x, for ii=1:y, if nz ~= 0, if fr(ii,jj)==0 nz=nz+1; else myout(n)=0; myout(n+1)=nz; myout(n+2)=fr(ii,jj); nz=0; n=n+3; end else if fr(ii,jj)==0 nz=nz+1; else myout(n)=fr(ii,jj); n=n+1; end end end end nz=0; myout(4)=n; %Do the same think for fg & fb - I ommited this part. out=myout(1:(n-1)); Also, does anyone have any other good ideas about how I could easily compress images? Furthermore, does anyone know of a good way to compare the quality of a compressed image with its original?