False Colors in Photoshop?
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*
- Load your image into Photoshop as RGB.
- Decide what, if anything, you want to keep 'the same' (i.e., "normal"), and take an eyedropper reading of that point. Write it down. (Tip: Use the persistent eyedropper [shift-click on the location with the eyedropper tool selected.] That'll help later.)
- Decide whether you want a minor color change or a major one. Based on that, and your image, swap 2 color channels.
Not three; that just moves the color balance around. But 2 will change things dramatically. You've now got a distorted color, but proper tonality image.
Swapping channels can be done a number of ways.
- The brute force approach of making duplicates of the 2 channels (drag the channel in the channel palette to the new document icon in the palette), Select All in the copy of one channel, then paste it into the original other channel, then repeat the other way. (For example, if I'm swapping Red and Blue, I'd duplicate the Red and Blue channels, Select the Red Copy channel, and Select All/Copy. Then paste that into the original Blue channel. Select the Blue Copy Channel, Select All/Copy, and paste that into the original Red channel.
- The plug-in approach. There are a number of free filters which do channel-swapping. Do a search at the major Photoshop tip sites.
- Record an action to do the first option, and just play it back when you want to do this.
- If you like the results you have, stop.
- If you want to bring the desired colors back to normal, go into the Hue/Saturation/Brightness, and shift the hue until the RGB values of the point you selected at the beginning matches what you wrote down. (I usually try to keep skintones the same.)
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.