The present invention relates to an image compression and decompression method, in particular in the areas of computer image processing and data compression. The currently, the process speed for which JPEG (Joint Photographic Experts Group, a compression standard) is applied, it's not all too satisfactory. One aspect of the present invention is simplify compression process based on particular features of an image, thus achieve the aim of accelerate the processing speed. Apply the process described in the present invention, the processing speed for JPEG compression/decompression would rise, without suffers quality reduction compare to current JPEG compression/decompression method.