[Shiraz (Ray)]

interesting questions Richard.

I think that I understand how drizzle improves resolution in dithered undersampled images, but I have been doing some experiments to see what happens to SNR under drizzle and do not yet understand the results. Drizzle certainly makes the pixels smaller, but am not sure what that means to sensitivity or how to use the equation in the presence of drizzle. Will post again when I get my head around what is going on.

Thanks for the encouragement Stefan.

regards Ray

edit: Drizzle definitely improves resolution by extracting slightly different high spatial frequency information from each of a set of dithered frames and then combining this information in the resulting stack - ultimately, more detailed information is available in the stack than is available from any single input frame. It doesn't change the optics/atmospheric resolution, but it does restore (partly) information that is lost through undersampling. It only works on images that have been dithered and that are undersampled.