Patent ID: 6415060
Filing Date: 2002-07-02
Classification: G06T

Abstract:
A reversible transform coding system which includes a reversible transformer which inversely transforms quantization values (Xq1 Xq7, Xq3, Xq5) into an integer four-element vector (u4, u5, u6, u7), said reversible transformer including:means for calculating global signals (p3, p5) and local quantization values (sq3, sq5) from the quantization values (Xq3, Xq5); means for determining quantization residuals (r1, r7) from the local quantization values (sq3, sq5) based on a third numeric table, means for multiplying the quantization values (Xq1, Xq7) by natural numbers k1, k7 and adding the quantization residuals (r1, r7) to the products to obtain transform coefficients (X1, X7), respectively; means for determining representative elements (s3, s5) from the transform coefficients X1, X7 based on a fourth numeric table; means for adding the representative elements (s3, s5) to the global signals (p3, p5) to obtain transform coefficients (X3, X5); and means for linearly transforming the transform coefficients (X1, X7, X3, X5) with an inverse matrix to a matrix [a1a7a3a5a7-a1-a5a3a3-a5-a7-a1a5a3-a1a7]-1â€ƒto obtain the integer four-element vector (u4, u5, u6, u7), wherein said means for calculating global signals (p3, p5) and local quantization values (sq3, sq5) from the quantization values (Xq3, Xq5) includes: means for calculating global signal candidates (p3(0), p5(0)) from the quantization values (Xq3, Xq5) based on two dimensional division with a matrix [h-ggh] â€ƒwhere g, h are integers which are given, from integers a1, a3, a5, a7, by g=a12âˆ’a72+2a3a5, h=a32âˆ’a52+2a1a7, respectively; means for linearly quantizing the global signal candidates (p3(0), p5(0)) with step sizes of real numbers L3, L5 to obtain global quantization value candidates (pq3(0), pq5(0)) and quantization residuals (r3(0), r5(0)); means for subtracting the global quantization value candidates (pq3(0), pq5(0)) from the quantization values (Xq3, Xq5) to obtain local quantization value candidates (sq3(0), sq5(0)); means for determining an index I from the quantization residuals (r3(0), r5(0)); means for determining local quantization values (sq3, sq5) and global difference signals (&Dgr;p3, &Dgr;p5) from the local quantization value candidates (sq3(0), sq5(0)) based on a fifth numeric table selected using the index I; and means for adding the global difference signals (&Dgr;p3, &Dgr;p5) to the global signal candidates (p3(0), p5(0)) to calculate the global signals (p3, p5).