IMAGE DATA COMPRESSION AND DECOMPRESSION METHOD AND DEVICE

Provided are an image data compression and decompression method and device to improve the coding efficiency and compression efficiency. The data compression method comprises: respectively quantifying the pixel minimum value and the pixel maximum value of an image block as a first quantization value and a second quantization value, the pixel minimum value and the pixel maximum value respectively corresponding to the quantization step number of a first quantization step and the quantization step number of a second quantization step; mapping the value of each pixel of the image block as the quantization step number of a third quantization step; and coding the first quantization step number of the first quantization step corresponding to the pixel minimum value, the quantization step number of the second quantization step corresponding to the pixel maximum value and the quantization step number obtained by mapping the value of each pixel of the image block and writing same in a code stream. The method provided in