This is a standard technique in astrophotography, you can see examples of combinations of 10 images that have been registered into one image in my web site, and the purpose?, you guessed it, to extend dynamic range of the image.. astrophotographers are trying to capture extremely faint objects..not even visible with the eye. I use Picture Window Pro 2.5, it will register images..even very large ones, without problems, it will also do everything PS does but in 48b mode. The web address is: www.dl-c.com , there you can download a tutorial that will show you how to do it. MCRich <[EMAIL PROTECTED]> wrote: >The speculation: > >Specialized software might facilitate such registration, even on large >files. The scientific literature about satellite base photography software >is replete with discussion of registration technique. Herm Astropics http://home.att.net/~hermperez