That's not quite right. I was a Photolithographer all through the 80's (and most of the 90's too), and as a "Colour Stripper" (cue jokes now), I took the seperated film from the scanner and did the actual retouching on a light bench with a paint brush and a retouching paste, (can't even remember what it was called now). It took a long time, as required a fair bit of skill, which is why we were paid quite well to do it. When Macs became fast enough, and Photoshop mature enough to do the job, we did it using those tools. Takes a lot less skill frankly, its just a matter of knowing what works and doing that again and again.