@javad danesh - you could use reshape to manipulate your array into a set of 8x8 blocks. Since 5872 is not divisible by 64, you would need to pad it. For example,
x = randi(256,1,5872);
xPadded = [x zeros(1,16)];
xReshaped = reshape(xPadded, 8, 8, length(xPadded)/64);
The first 64 elements of xPadded make up the first 8x8 block of xReshaped, etc.
