False Colors in Photoshop?

by Kevin Connery connery@keradwc.com

If you want the 'false color' look of Color IR, there's an interesting 'cheat'--see below. For Black and White, I don't know of one, but you could break it into the component issues: the halation glow (the really obvious aspect of IR--even though it has nothing to do with IR itself, but the film backing) and the spectra response.

False Color in Photoshop*

TIPS: This is subject-matter dependent. If the only things in the image are neutrals (whites, greys, blacks), it'll not have much impact on them. (Brides will probably not appreciate having a white dress and green skin, however.)
Swapping Red and Green or Red and Blue will usually make much bigger changes than swapping Green and Blue.
Scenes with a lot of grass and sky are good candidates for this kind of manipulation.
Studio portraits aren't really good candidates, but that's the example below anyhow.

I started with a somewhat warm image, and took a reading of the girl's left cheek. It showed 236R, 199G, 190B. I then swapped the Red and Green channels for the biggest effect (this is a demo, after all...). Then I use Hue/Saturation to bring the cheek values from 199R, 236G, 190B back to close to where they'd been, letting the rest of the colors go where they would. Note that the clothes changed color slightly, the hair was dramatically changed, the skin was only a little different, and the white blouse was mostly unchanged in all the cases.

*The concepts should be usable with any imaging package which supports channels. These specific steps are for Photoshop.