1. A method for image compression, comprising: (a) partitioning an image into a plurality of image blocks, the image having A×B pixels, each of the image blocks having N×M pixels, wherein N is less than A and M is less than B; (b) selecting one of the image blocks as a selected image block and outputting to an encoder; (c) compressing the selected image block into a compressed image block conforming to a specific image file format and storing the compressed image block; (d) repeating step (b) and step (c) until all of the selected image blocks are compressed into the compressed image blocks; and (e) generating a compressed image file in the specific image file format according to the compressed image blocks stored in the memory.