An image dithering module is provided. The image dithering module includes a plurality of data processing channels. The data processing channels respectively process image data of each pixel or sub-pixel in an image frame. Each of the data processing channels includes a bit processing unit and a bit truncator unit. The bit processing unit mixes first pixel data with random data to generate second pixel data. The bit truncator unit truncates partial bits of the second pixel data to generate third pixel data.