Abstract: The methods of the invention can be used with image data divided into domain blocks. A predetermined search pattern of range blocks centered on a domain block is defined for use in the methods. The first method includes a step of generating at least one error descriptor data based on domain block data and range block data. The error descriptor data can be derived by scaling the range blocks to the pixel size of a domain block, and subtracting the means of the range blocks and domain block from each pixel thereof. The mean-adjusted, scaled pixel intensity levels of the scaled range blocks are subtracted from mean-adjusted pixel intensity levels of the domain block to produce difference data. The absolute value of the difference data is taken and the positive difference data are summed to produce summed error data for each range block. The summed error data is used to derive at least one error descriptor data for the image.