A method for compressing an image including one or more blocks, each of the one or more blocks including an x channel, a y channel, and a z channel, the method including, for each of the one or more blocks: performing a frequency domain transform, by a processor, on each of the x, y, and z channels; ordering, by the processor, the transformed x, y, and z channels into first, second, and third transformed channels; performing an inter-channel transform in accordance with the order of the first transformed channel, the second transformed channel, and the third transformed channel; and encoding the inter-channel transformed channels.