1. A method comprising: generating pixels of an image for a bistable display using halftoning based on data of one or more previously displayed images, wherein generating the pixels comprises: generating a first output in response to a gray level quantization error; generating a second output for each pixel in response to an error value that is based on a display quantization error associated with said each pixel; adding the first and second outputs to create a third output; and subtracting the third output from input image data.