Images are subband transformed to create a plurality of subband images. Each
subband image includes a plurality of pixels. Each pixel is represented by a plurality
of bits with each bit associated to a certain quantization level. Encoding of an
image requires scanning essentially all the bits of essentially all the pixels
of the image. While scanning in a particular order, one can exploit dependencies
within groups of bits consecutively scanned for encoding purposes. Thus, bits of
groups can be encoded together. In a subband and transformed image, the scanning
order or scanning curve is defined by indicating in which order the system traverses
the several subbands and the several quantization levels. One method is characterized
in that the set of scanned bits which will be encoded together, and which thus
form a group, bits of at least two different sub-images and at least two different
quantization levels are recognized.
