How I now create HaRGB images from Ha and RGB images. This method results in Siril registered stacked Ha and RGB images which are combined in Photoshop.
Process Ha light frames with corresponding darks, flats and biases using OCS_Extract_Ha script (can be done manually).
Process RGB light frames with corresponding darks, flats and biases using OCS_Preprocessing script (can be done manually).
Load and convert pp_light frames for Ha and RGB together creating a single sequence for all.
Register the single sequence of images (this aligns all images).
In Finder (Mac) or Files, separate r_pp_light Ha and RGB images into separate files.
Create two new sequences one for each of the registered Ha images and RGB images.
For each sequence, Ha and RGB created above, stack images.
The stacked Ha and stacked RGB can be enhanced in Siril before being saved as tif files for use in Photoshop.
Finally, use these two images in Photoshop and follow the steps in https://astrobackyard.com/tutorials/hargb-astrophotography-tutorial/ to produce your HaRGB image.
- Create HaR: Add red channel of RGB to Ha image at about 25-30% opacity.
- Create New RGB: Add HaR to red channel of original RGB. Apply Noise-Dust & Scratches to blur slightly.
- Create HaRGB: Add Ha as layer to New RGB with blending set to Luminosity at about 75%.
- Make other adjustments as needed.