This is a classic exercise about the use of the additive colour model red-blue-green. The reason I spent some time playing around with the separation of the additive primary colours has a lot to do with my traditional photography training. All the people that, like me, learned photography using film, had in the past to come to a compromise because film (and consequent printing) was an expensive process therefore experimentation in photography was something to do in moderation. Today, with digital photography, this limit has been overcome and all creatives can enjoy the good old times experimentation with little waste of money.

RGB separation is today a very easy process; if once we were forced to screw one after the other three filters on the lens, today many graphic programs are able to do the same thing in a matter of seconds, giving us also the possibility to play around with every shade of the colour spectrum.

The pictures that follow show the setting in Photoshop I use to form the RGB layers. It’s basically the same workflow used to merge together multiple exposures: you start with three (or more) photos, underexpose them a little and then use the “screen” mode to blend them together. The difference is that before the blending, you can add an extra layer for the colour and, to simulate the filter, you have to set the blending mode of the colour on “multiply”. If you click on the pictures to enlarge them, you’ll understand better what I mean; it’s really an easy process (even though a little time consuming). The three original photos I use here are a sequence showing a bus travelling towards me.

Basic red/blue/green separation.

Cyan/magenta and yellow version

Orange/lime green and purple funky version