Removing cosmic rays and other randomly positioned spurious events from CCD images by taking the lesser image-statistical theory for the general case
L. Kay · Measurement Science and Technology · 1992
If two optical images of the same scene are obtained using a CCD, a third image (called the lesser image) may be formed in computer memory by taking the lesser of the two counts in each pixel. The process may be used to remove, or greatly reduce, the effect of spurious events such as cosmic rays. A complete statistical theory of the lesser image is given for the general case, thereby facilitating recovery of the true image from the lesser image.