1. A method for decompressing a compressed image data in a luminance and chrominance space, the image data having a plurality of pixels wherein each pixel has a luminance channel and at least two chrominance channels, the luminance channel being encoded with a higher bit allocation than each of the chrominance channels; the method comprising: interpolating the chrominance channels for the pixels so that the chrominance channels have the same bit allocation as the luminance channel; and for each pixel: establishing a window including the pixel and neighboring pixels; comparing a bit value for the luminance channel for each neighboring pixel to a bit value for the luminance channel for the pixel; and for each neighboring pixel having a bit value for the luminance channel that differs from the bit value for the luminance channel for the pixel by less than a threshold, averaging the bit values of at least the luminance channel for those neighboring pixels and the pixel to output averaged bit values for at least the luminance channel for the pixel.