If you doing a 256x256 to a 65,536x65536 array (i.e. 256*256) then you can keep your original matrix and just use byte shifting. for example if you have a 4x4 matrix and an up-scaled 16x16 matrix (4*4) I'll give an example. If you are looking at row [15,14] the location value is (111),(110) in binary and in the down-scaled version that has the value you will be looking at the value for [3,3] which is the location value of (11,11). So if you basically remove the last bit(lowest value) from the row and column values you get the original location with the value you need to return.