Lossless image compression method

A lossless image compression method, for processing an image having a plurality of pixels, wherein an image width of the image is W, the lossless image compression method comprising:

• (a) selecting N continuous pixels from the image, where N is a positive integer greater than or equal to 2 and is less than the image width W;
• (b) performing a differential pulse code modulation (DPCM) means, so as to obtain N non-negative differences corresponding to the N pixels according to values of the N pixels, the DPCM means comprising:
• obtaining N pixel differences individually corresponding to the N pixels according to the values of the N pixels;
• and
• performing a main means on the N pixel differences individually, so as to obtain the N non-negative differences individually corresponding to the N pixel differences, the mapping means comprising:
• when the ith pixel difference di in the N pixel differences is greater than or equal to zero, obtaining the corresponding ith non-negative difference ni by multiplying the pixel difference di by 2, where 0<=i<N;
• and
• when the ith pixel difference di in the N pixel differences is less than zero, obtaining the corresponding ith non-negative difference ni by subtracting 1 from a result obtained by multiplying the pixel difference di by 2;
• (c) calculating to obtain a coding parameter according to the N non-negative differences;
• and
• (d) coding the N non-negative differences according to the coding parameter.