Method and apparatus for avoiding image flicker in an optical projection display

One embodiment of the invention is a digital filter that avoids image flicker in a projection display that has two operational modes. This digital filter avoids undesired intensity variations between successive frames by changing all the assigned pixel values by the same amount during either of the two modes. This digital filter typically only needs to correct some of the least significant bits ("LSB's") of the pixel values during either operational mode. This is because the dynamic range of the flicker is often very limited (e.g., it is often less than 5%). In fact, some embodiments combine the flicker-filtering function with the dither-control function, if the correction of a LSB causes an over correction of the flicker problem.