Planetary Image Processing

Iceman(external link) posted(external link) some outsanding Jupiter photos in the Bad Astronomy(external link) / Universe Today(external link) Astrophotography Forum(external link). Responding to a question, he provided this explanation of his processing technique.

I save the avi as BMP's because the program "ppmcentre" only works on bmp's.
"ppmcentre" does 3 things for me:

1. Centers the planet in the frame. This is very useful when your tracking is not accurate and it drifts around a lot. After running through ppmcentre, all frames will have the planet in the centre. Very handy for registax, as it aligns them quicker and better.
2. Crops the frame (to 400x400 usually). This is just so registax runs through the frames faster
3. Ranks the frames. It has an option to analyse the quality of each frame (using an algorithm similar to the "gradient" algorithm in registax), and then renumbers all of the frames so that the best quality ones are at the top of the list. This again helps to weed out the bad quality frames (you can delete them) before taking them into registax. I find it also helps registax align and optimise the frames better if they're already pre-sorted with best quality first.

And yes, I do process the R/G/B channels separately rather than colour processing. The ))ToUcamis a colour camera, but i've found that splitting into R/G/B channels and processing separately helps registax align the features better and produces a better quality rank and optimise, and therefore a better final stack. I pass each channel through registax and apply the same processing, and then the 3 channels are further processed in?AstraImagebefore being recombined in?AstraImage((.

Ideally, I'd have a monochrome camera with colour filters to CAPTURE the channels separately as well. This gives the advantage of full resolution in each channel, and the ability to refocus each channel, as the blue channel especially can be at a slightly different focal point than the others, and it's more susceptible to atmospheric distortion.

My processing routine is as follows:

  1. Virtual dub to save avi as bmp's
  2. "ppmcentre" to crop frames to 400x400 (usually) and rank based on quality
  3. split into separate r/g/b frames
  4. align and stack separate rgb channels in registax. Create reference frame with wavelets 3@10, 4@15.
  5. Stack 100 frames of each channel, Wavelets applied 3@10ish, 4@13ish, 5@18ish, save as tiff
  6. Open the 100 r/g/b channel images in ))AstraImage((, Convert to greyscale, LR deconvolution 7/1.4, Recombine (with R/B shift), Gamma adjust 0.7, Save as TIFF
  7. Slight curves and unsharp mask of each image in photoshop, save for web.

That's what I did for these images. The routine is mostly the same for all of my images, but the amount of wavelet processing and/or LR/ME deconvolution in ))AstraImage(( changes depending on the quality of the original frames.

Created by Andy. Last Modification: Sunday 31 of October, 2010 17:04:29 CDT by Andy. (Version 1)