When I convert redscale images I get these blue spots all over the image. It happens 95% of the time and I can’t figure out why. If I convert the image without cropping into the frame it gives me a much better result.
Yes, I think redscale would benefit from this, because including the film border (or in your case, even some of the underlying light source), will provide a sort or baseline for the white point and black point needed to convert the image.
Otherwise, with redscale, Negative Lab Pro will still try to “normalize” the colors in the image, as it would for regular negatives. In this particular image, it looks like it has elevated the noise in the shadows (the negative is very thin and probably underexposed when shot), and then tries to balance the extreme red by adding blue.
I don’t have a good sample of redscale, but I may be able to add some option that improves handling redscale. If you would be comfortable sharing any raw scans of redscale, please feel free to email me a link to nate@natephotographic.com.