Film Simulation with GIMP: 1 - Black and White

OK, so we already saw how to make a black and white image out of a colour one using channel mixer in GIMP. We might select any proportion (even negative...) for each of the primary channels, Red, Green and Blue. This way, we can produce any interpretation of the original colour information.


Have you ever thought how it worked in "old" films? Silver halide salts (most commonly used chemical in B&W films) reacted in different ways to each light wave length (or colour...), depending on chemical composition and layering of the actual film. As a result, each brand and type of film had a

slightly different performance in similar light conditions. On the other side, panchromatic films were supposed to react in a similar way to all colours.

Left: Original - Center: Agfapan 100 - Right: Ilford Pan F

Independently from film grain (I might deal about this in a later post), the representation of colours in B&W film was quite personal, and most photographers ended up using a "preferred" film. Now, is it possible to reproduce that personal film "feeling" with image editors? Well, we can try...

Basically, what we will do is to use specific conversion values in the channel mixer, as a first approach. From the great Petteri blog page (http://www.prime-junta.net/pont/How_to/100_Curves_and_Films/_Curves_and_films.html), you can get, for example, the following proposals:

Agfa 200X	18,41,41
Agfapan 25	25,39,36
Agfapan 100	21,40,39
Agfapan 400	20,41,39
Ilford Delta 100	21,42,37
Ilford Delta 400	22,42,36
Ilford Delta 400 Pro & 3200	31,36,33
Ilford FP4	28,41,31
Ilford HP5	23,37,40
Ilford Pan F	33,36,31
Ilford SFX	36,31,33
Ilford XP2 Super	21,42,37
Kodak Tmax 100	24,37,39
Kodak Tmax 400	27,36,37
Kodak Tri-X	25,35,40

By using these values, you will obtain different results, depending on the selected "film setting". You might have not chosen these specific settings - but this is a fair approximation to what B&W films did...

Next: Film Simulation: 2 - Colour (Theory)