AN IMAGE-RESTORATION TECHNIQUE FOR THE REMOVAL OF COSMIC-RAY HITS FROM DITHERED IMAGES

A method is proposed to find and remove cosmic rays from stacks of images which are not registered. Such dithered images obtained with undersampling cameras, such as the Wide Field and Planetary Camera 2 (WFPC2) on board the Hubble Space Telescope, can be used to recover some of the resolution lost by a large pixel size. The proposed method simultaneously cleans the images of cosmic rays and deconvolves them. Cosmic-ray hits are dynamically identified at each iteration. The output is a combined and restored image and a list of cosmic-ray hits for each of the input images. The final lists of cosmic-ray hits are useful even if a restoration of the images is not desired. A simulated application of the method to WFPC2 images is presented.