Forgot to remove Red filter from taking lens after switching from the B&W to Velvia 100. (O.K. I know, I know, but it's not that funny!) I'm about to use my scanner for the first time on the salvaged portion of the roll and was wondering if there's an editing tool in P/S (or other) that might compensate for the film effected by filter.
The quantity of red to remove might be doable -- try it. First try subtracting equal amounts of green and blue in curves; Add overall density as needed; when or if you run out of GB (or just before the highlight or shadow ends go up against the wall) switch to the Red channel add Red; remove density as needed.
You can also go into selective colour, choose 'reds' and reduce to taste.
There may be a 'trick,' but its one I'm unaware of.
I think you may find this difficult. A red filter is a low pass filter. It passes light frequencies that are long (red and infrared) while absorbing higher frequencies (green, blue, etc.). IOW, your film likely recorded very little green and hardly any blue. And if it's not on the film...
But... I've been wrong before. One way to proceed might be to scan a frame that has what you know to be essentially white (specular highlights, white concrete, etc.). This will allow you to pick out the red color from the filter as if it were a "mask" over the film. Delete the mask (no, I don't know how, never done it myself, but I know it can be done) so that the white parts become white again. What's left should be all that's recorded on the film. Go from there.