Colour infrared photography gives false colours anyway, so you could argue that it doesn’t really matter what you do on the computer because who’s going to say that you got the colours wrong.
When Kodak’s colour infrared film was around (supplies are about to end) skies would come out magenta without any filter, while with a yellow or orange filter, they can be green and foliage bright orange. The colours would also be rather intense and very saturated. Using that film was great fun.
With digital, you can obviously take control of colours to a significant extent, but you probably should not be over zealous with the colour controls.
1 Fine-tune exposure
The photograph was taken on an infrared-converted Canon EOS 5D fitted with a TS-E 24mm wide-angle lens. The original was slightly overexposed so the sunlit trees needed darkening down a little. Here, I used Adobe Lightroom 3 and the Graduated Filter, and then used the Exposure slider to darken down the sky.
2 Channel swap, red
Go to the layers palette and go to Create a new layer or adjustment layer icon and select Channel Mixer. Next channel swap. Go to the Channel Mixer. In the red channel which is showing by default, change the red value from 100% to 0% and the Blue value from 0% to 100%. Leave the Green slider alone.
3 Same again in blue
Click on the Output Channel and you will see the options for Green and Blue. Select Blue, and move the Red slider from 0% to 100% and then the Blue slider from 100% to 0%. Again the Green slider is left alone.
4 Contrast control
You now have a decent false colour image but the contrast needs a tweak because it’s rather flat right now. Go to Create a new layer or adjustment layer icon again and this time choose Curves. Adjust the Curves until you get the desired contrast. Mostly, I just click the Auto button and find that Photoshop can do a decent job.
5 Fine-tune colours
Yet again I go to Create a new layer or adjustment layer icon and select Hue/Saturation to fine-tune colours. This is obviously a matter of taste, but here you can intensify colours to bring out sky detail and just generally pep up the result.
6 Final step
If you have finished, go to Layer>Flatten Image. If you think you may want to revisit the image later, save it with the adjustment layers in place and then you can tinker with the image in the future.
Taken from the July 2011 issue of Advanced Photographer magazine