The present invention provides an apparatus and a method for image processing. The apparatus for image processing comprises an encoding circuit, which can select two reference pixels according to two reference pixels and produce a maximum pixel value and a minimum pixel value according the two reference pixels. The present invention further comprises a color-difference operational unit for selecting a plurality of color pixels as a basic pixel, a first color pixel, and a second color pixel. When encoding the basic pixel, a first color difference, and a second color difference, respectively, first encoding data corresponding to the basic pixel, second encoding data corresponding to the first color difference, and third encoding data corresponding to the second color difference are produced, respectively.