Part of the reason for posting here is to get feedback on the process and to do that you need to show your work.
#1 is a pretty ordinary HDR cloud image. Shot in color with my D850 this afternoon, it is essentially monochrome even with the saturation turned up. Nice enough, but I thought I'd fool with it some. In another version, I turned the saturation up past the point of clipping but that looked awful and was discarded. I decided to abandon objective realism.
#2 is an unedited (unrepaired or unretouched) B&W studio picture I took of my then-girlfriend back in 1968. 35mm Tri-X, 50mm lens, Mamiya-Sekor 500DTL. I haven't seen her in more than fifty years. Assuming she is still around somewhere, I don't think she'll mind me sharing this.
#3 layers #1 with a small section of #2. I colorized both layers independently with Photoshop's neural colorization filter. I inverted #2 so it was a negative. There was some interaction on the left side between the layers that I could not resolve, so after I merged the layers I retouched it out of existence with AaKVIS Retoucher. Finally, I made some minor hue and saturation adjustments.
At this point, I thought things were weird enough not to require a funky border.
While this would not have been impossible back in the pre-Photoshop days, it would have been extremely difficult and way beyond my humble capabilities. If someone was doing this sort of thing in color, I don't know who it would have been. Even Jerry Uelssman always worked in B&W.
This is really cool. The second photo has that old-time noise, and it's maintained in the final mixed image to create nice texture. The color in the final image is amazing too. You lined everything up just right. I really appreciate what you did here. It would make great album art for a band.
Thanks for sharing the results of your experiment Andrew.
I once had a friend on another site that made pure abstracts by pushing the sliders way to the right. The results might not have been to everyone's taste but the images were so unique they made some pretty big sales.
Keep on playing and creating!