A 2-D VECTOR EXCITATION CODING TECHNIQUE

We present a VQ-based technique for coding image data that adopts an a nalysis by synthesis approach. We define a new type of spatial interac tion model for image data, called prediction pattern, which we use alo ng with a excitation vector, to generate an approximation of an input block of pixels. A prediction pattern is a k x k array with each eleme nt representing a prediction scheme from a given set of predictors. A prediction pattern captures the spatial dependences present in an imag e block. Given a codebook of prediction patterns and a codebook of exc itation vectors, we encode an image by partitioning it into blocks and for each block identifying the prediction pattern from within the cod ebook that best models the spatial dependences that are present in the block. We then search the excitation codebook for a code vector that in combination with the already chosen prediction pattern results in t he synthesis of the closest approximation to the current image block. We present algorithms for codebook design and give implementation resu lts. The proposed technique gives promising results. (C) 1998 Elsevier Science B.V. All rights reserved.