Patent ID: 8428381

Claim:
An image compression method with a variable quantization parameter, for processing a plurality of pixels of an image, the method comprising: receiving N successive pixels; obtaining N pixel differences and N map differences corresponding to the N pixels according to values of the N pixels through a differential pulse code modulation (DPCM) means, wherein the DPCM means comprises: obtaining the N pixel differences respectively corresponding to the N pixels according to the values of the N pixels; and performing a mapping means on the N pixel differences respectively, so as to obtain the N map differences respectively corresponding to the N pixel differences, wherein the mapping means further comprises: when the i th pixel difference d i in the N pixel differences is greater than or equal to 0, obtaining the corresponding i th map difference n i by multiplying the pixel difference di by 2, where 0<=i<N; and when the i th pixel difference d i in the N pixel differences is smaller than 0, obtaining the corresponding i th map difference n i by subtracting 1 from a result obtained by multiplying the pixel difference d i by 2; calculating to obtain a quantization reference value corresponding to the N pixels according to the N pixel differences; obtaining a quantization parameter corresponding to the N pixels according to the quantization reference value; and encoding the N map differences according to the quantization parameter.