Progressive transmission of images using subband coding

The authors investigate the application of subband coding (SBC) to the progressive transmission of images. The main objective of progressive transmission is to allow the receiver to recognize a picture as quickly as possible at minimum cost. After this it can be decided to receive further picture details or to abort the transmission. SBC turns out to be very suitable for such a system, because the low-pass version of the image is easily recognized for any image type. Further details of the picture are obtained by sequentially receiving the (encoded) higher bandpass versions of the image. Because SBC has good data compression properties, not many bits are needed to transmit the low-pass image and the other subbands. Comparisons to other progressive transmission schemes, such as 8×8 block DCT (discrete cosine transform) encoding, show that SBC is favorable, both in mean-squared error and in a subjective sense