[1Feb23] I have been thinkimg of TriColour for a while but this was given impetus by finding chatty yet informative 2021 article by Amy Elizabeth. Any poses the question, " Why Would You Try Trichromatic Photography?" when colour film is readily available; and answers "Well, because it’s fun and oddly satisfying to get a color image from three black and white images". Any is, of course, working in analogue and so the question is even more pertinent to my digital experiment where I am asking my XE3 to ignore the colours and then trying to restore an approximation: I will try to answer that if it works.
On exposure adjustments for film, the article comments,
I found that the blue and green filters needed about 2 stops of overexposure, and the red filter needed about 3.5 stops of overexposure. Amy Elizabeth, TRICHROMATIC PHOTOGRAPHY
I bracketed the exposures +2 and -2 for each image and expected the camera to get it right anyway. That is not quite what happened. Here's my first attempt at a still life
At first glance, the red looks ok (fig. A7), but the blue looks best +2 (A2) and the green somewhere between 0 and +2 (A4 and A5). It will be noted that my figers are visible on the blue set.
Amy goes into some detail on the Photoshop processing needed — that's what attracted me to the piece - and provides a video.
1 open the three images (fiddle the names for ease of reference)
2. combine them as layers - the video demo method didnt fork for me, I created a tiff file, pasted them in one-by-one , renaming the layers as you go
3. for each layer, channel, blending options, turn off the two which aren't the filter used
Well, that's an almost complete failure (fig. B1), though the ghosly image of finger ends in blue shows that something is happening as expected. The layers all seem to be the right colour (fig. B2). Try again tomorrow.