Radha, The way you wrote this message sounds like you are wanting to move this window around interactively, like dragging it with a mouse. But although that is the way that it sounds, I am guessing that you actually want this kernel to process your entire image programatically, without any user input. Is that right? If so, have you looked at any of the options that are presented with examples in IDL's 'Online Help -> Contents tab page -> User's Guides -> Image Processing in IDL -> Contrasting and Filtering'? There are several kernel-based filters there and those perform all their "movement of kernel" in just a one-line code call. James Jones