Color image coding by vector subbands/ECVQ and activity map

A novel vector subbands/ECVQ approach for image coding is presented which incorporates the concept of activity map. A key issue in vector subband coding is the efficient compression of the small energy-albeit perceptually significant, upper-bands of the decomposed images. As the components of the significant vectors in the upper subbands display the contour information of the original images, therefore, the locations and orientations of such (predominantly) edge information can be determined from the original image. The availability of this knowledge motivated us to generate the activity map, which in turn is used to obtain transmission control maps. The control maps are used to turn on/off the transmission of vectors. Most importantly, the approach is extended and applied to color image coding. Experimental results show remarkably good performance of the proposed approach.