1. A method for image dithering, comprising: comparing gray levels of adjacent sub-pixels of the same color in each row of pixels of an image block; adjusting a first counting number if the gray levels of adjacent sub-pixels of each color in the same row of pixels are in ascending order or in descending order; and performing image dithering in temporal domain according to least significant bits of the gray levels of the pixels of the image block according to a procedure of dithering that corresponds to the first counting number.