Creating false-color IR images

What is false color?

With false color I’m referring to what Kodak EIR Ektachrome film does. This means, that the IR part of the spectrum is represented with red color, the red part of the spectrum is shown in green color and the green part in blue color.

This means that the mapping of channels changes from (red → red, green → green, blue → blue) to this:

IR → red
red → green
green → blue
blue → discarded

More information on how to shoot in IR.


What does it mean?

It means you have to take 2 images for every false-color shot.
One has to be in IR and the other one in visible light. They have to be perfectly aligned, so the camera shouldn’t move between shots. It’s best if you use a tripod.


Image in visible light


Image (same scene) in IR


Then what?

Next, you have to combine both shots in Photoshop (or some other program), replacing the channels like shown above.
Before that, I used Auto Levels to equalize the IR image;


Channels in Photoshop


Remapping channels

You have to start from the back though — first you have to select only GREEN channel, copy the “green part” of the image, select BLUE channel and paste “green part” into it.
Next, select RED channel, copy the image and paste it into GREEN channel.
Finally, select your IR image, copy it, then select only the RED channel of the visible light image and paste the IR image into it.

You should get something like this:

False-color imitation of Ektachrome