LOCALLY VARIABLE QUANTIZATION AND HYBRID VARIABLE LENGTH CODING FOR IMAGE AND VIDEO COMPRESSION

摘要

A coding method, apparatus, and storage media with instructions to carry out a method. The method operates on an ordered series of transform coefficients of a block of image data, and for a fixed quantization method, and includes quantizing and encoding the ordered series to form a coded bitstream. The quantizing and encoding uses one or more variable length code (VLC) mappings. The quantizing includes quantizing to have amplitude-1 at least one coefficient that would be quantized by the fixed quantization method to have zero amplitude, quantizing to have zero amplitude at least one coefficient that would be quantized by the fixed quantization method to have amplitude-1, and using the fixed quantization method to quantize any coefficient that is quantized by the fixed quantization method not to have zero amplitude, amplitude-1, or amplitude-2.