An exemplary data arrangement method for a picture includes at least the following steps: obtaining pixel data of a plurality of first N-bit pixels of the picture; and storing the obtained pixel data of the first N-bit pixels in a plurality of M-bit storage units of a first buffer based on a raster-scan order of the picture, wherein M and N are positive integers, and M is not divisible by N. Besides, at least one of the M-bit storage units is filled with part of the obtained pixel data of the first N-bit pixels, and the first N-bit pixels include at least one pixel divided into a first part stored in one of the M-bit storage units in the first buffer and a second part stored in another of the M-bit storage units in the first buffer.