FIlm Simulation 3: Colour - Cross Processing

Cross processing was a nice way to tweak the colours in the original captures. Basically, slide film was processed with the standard C-41 negative film process.
Overall contrast was increased, then yellow and blue shades might appear. In general, colour was distorted - but this effect was sought-after, indeed...

Film Simulation: 2 - Colour (Theory)

The previous post showed how to produce simple B&W conversions through the use of the channel mixer with fix channel proportion values, to mimic the behaviour of specific traditional, chemical B&W films.

GIMP - Curves adjustment

One of the easiest and more powerful adjustments in graphic edition is the curves adjustment. However, lack of clear, simple indication has made users afraid of trying it... let's try to fix this.

The concept
First thing you have to make up your mind is colours. White is white, black is black. Then, a 50% grey is a 50% grey. Simple, ain't it?
OK, then open any image in GIMP. You can launch the curves tool through "Colours -> Curves...", either from the upper menu or by clicking the right button anywhere on the image surface.