Processing a terrestrial nightscape in PI?

[barque]

Hi,

What's the best way to process a terrestrial nightscape in PI? In other words, if I have a set of lights/darks/bias with both sky and terrestrial foreground, and I want to align and stack the sky, and the foreground, what's the best way to approach it? I'm familiar with the program starry landscape stacker, but would like to use PI to take advantage of PI's preprocessing and other features.

Here's what I've come up with:

- calibrate and debayer with lights/darks/bias in PI
- convert debayered key frame image to 16-bit tiff
- build mask using tiff in photoshop (or with range mask in PI)
- using mask and calibrated+debayered lights, create masked lights using PI (how to save masked images in PI?) or photoshop
- register and stack masked lights (sky)
- stack unmasked lights (foreground)
- process to taste in PI
- compose sky & foreground in photoshop

Is there a better or more efficient way to approach this workflow? Attached is an example of the kind of image I have in mind (done in SLS).

Thanks!
 Rob

[barque]

For computing the masked images, doing Pixel Math with an expression of:

min($T,foreground_mask)

and the output configured to be RGB color, and applying the Pixel Math to an image container holding the debayered light frames seems to do the trick.