brainstorms

Wednesday September 28, 2005

notes on converting color images to b/w

vacuous motto: there is more than one way to do it. [dear oh dear, where did that smiley go?] the earliest opportunity for a B/W conversion [for a DSLR user] is during the raw image process. for example, in photoshop camera raw, one can pull saturation to 0, adjust exposure, contrast [etc] to taste. i have not used this much. [nikon capture editor also has a photo effects tool with black-and-white conversion.] past raw, i alternate between two techniques in photoshop: lab conversion [mode Lab color, isolate luminance channel (delete a,b) and adjust curve] for portraits, and channel mixer [select monochrome, mix r+g+b to taste] for architecture and landscape images. [i find channel mixer very difficult to control for portrait conversions. i do not know what i would use under gimp. lab mode and channel mixer are not available, but scripting it is much much easier, so i would not be surprised if there are some good script-fu ways of doing B/W conversion.]

all photoshop books have a section on B/W conversion, but not all of them cover more than the two techniques mentioned above. i like the high-contrast technique [using a gradient map] in scott kelby's the photoshop cs2 book [alas this edition seems to have dropped an interesting technique of over boosting r+g while reducing b for landscape images] and channels as layers technique in john paul caponigro's inimitable adobe photoshop master class [second edition]: the essential guide to revisioning photography.

other bits:

john paul caponigro's tutorial and photoshop conversion action is found amongst adobe's pro primers.

northlight images has an excellent reference page for converting colour images to black and white.

software: usually in the form of photoshop plugin or automation. the affordable ones seem to be photokit from pixelgenius and ConvertToBW Pro v3.0 from the imaging factory. photokit interface is dated and simple, but works fine: it includes 141 most common type of conversions. [excellent examples page shows you everything you need] converttobw filter comes with a modern interface, sliders and color response presets but will require more time to to set up a conversion library. [for now i am leaning towards photokit because it just does the job. i do not have darkroom experience, and like martin blank said, i just want the protein.]

image: a portrait of my good friend chris pilson, 1999. [chris, i hope you approve of this image] B/W conversion through luminance channel with curves. nikon 801s with nikkor 85mm f/1.8, fuji reala.

music: nicholas payton, payton's place [with guests wynton marsalis, roy hargrove, joshua redman], verve, 1998.