Drizzle with non-undersampled images

[Luigi]

I was playing around with stacking some images of the Moon I took with my Nikon D610 (5.95um pixels) and my 1200mm (focal length) refractor. I don't believe I'm undersampled, but I stacked both the 'normal' way and then with drizzle. The Drizzle Integration produced an image 4x larger and it looks 'great', but have I simply found a hugely memory-intensive way to enlarge?

[pengsloth]

I have done the same thing with some deep sky stuff. It really doesn't help from what I have seen unless you have an extremely high amount of data (like over ~50 sub frames) and dither like a mad man. Though with the moon you might be undersampled if you are attempting Lucky Imaging...

[Luigi]

Only 14 subframes. My mount was tracking at the lunar rate but of course that is an average rate and only in RA so no doubt there is a small amount of drift in between frames.

With the seeing around here I'm not sure I can undersample ..

[pengsloth]

I would say there is no increase it data quality with only 14 images.

[jkmorse]

If you are not using dithering, drizzle is of no value.  It only works because the dithering puts the image components in a different location each time and the drizzle algorithm then takes that varied data to increase resolution.  Minor movement between frames that is not driven by dithering is not going to do anything. 

Best,

Jim

[MortenBalling]

My personal experience, is that Drizzle works fine, but as jkmorse and pengsloth says, dither is important. It always is.

Another thing I've noticed: When you upsample your image, before post processing them, you tend to be more critical about your processing. You evaluate previews better, it's easier to control stuff like deringing etc. If you then use a 60-80% downsample as the final step, you'll get better results. Not very scientific, but we humans aren't that scientific, when it comes to aesthetic decisions.

Morten