Digital Infrared Processing Part II – False Colour

Exploiting the varying amounts of Infrared light that different objects give off leads to dramatically coloured shots. In this part of the series I’ll take you through how I post processed a recent pic taken on a Flickrmeet.

 

First things first. If you shoot RAW be prepared to have to make a side step before beginning the the processing. If you followed the previous article and shot with a custom white balance, you will need to avoid using Adobe Camera RAW, the RAW processing tool that acts as Photoshop’s front end. This tool can’t recognise the custom white balance setting, as it will be outside of ACR’s range. The image will open in ACR as a purely infrared image.
So we need to open the shot in another package first to retain the information set with the custom white balance shot. As you know, I’m using a Canon 40D, so I also have Canon’s own DPP package which, as it happens, does retain the custom white balance information. From there we can send the shot to Photoshop as a TIFF.

I will apologise to non Canon users at this point! I can offer one solution to this problem for others, which is to shoot JPG for this type of photography. This will retain the custom white balance at the time of shooting as part of the image, so no need for hassle and off to Photoshop we go! The TIFF that DPP generates looks like this :-

With some subjects this kind of processing works well already. Some of my other shots have a similar colour palette as it is simply the result of the custom white balance straight from DPP.

The first step on the path to trying out some false colour work is to swap the Red and Blue channels. In our image, the blueish trees will now go red(ish) and the browny red sky will end up a dark cyan, which is a bit closer to blue than murky brown!! To do this we add a new Channel Mixer adjustment layer and in the Red tab set Red to 0% and Blue to 100%. Then on the Blue tab, we set Blue to 0% and Red to 100%. After a while doing this gets really boring, so I made an Action to do it for me!

So now we can see the colours starting to appear but the image looks a bit flat and dull. Use a Levels or Curves adjustment layer and hit Auto (yeah, like you can navigate those weird channel swapped colours in manual mode? – just hit auto and tweak to taste!).

Its starting to look good now but I often then add a Colour Balance adjustment layer and tweak around a bit to get rid of either a cyan or reddish tinge.

The only other steps I performed on this image was to increase the effect of the pink trees using layer masks and colour balance layers to bring out the reds here. After that I used a Selective colour layer on the line of rushing water at the bottom of the wall and made the whites a bit more white, as they had changed a bit bluey in the colour balance process.

Last step was to create a new layer, using Option (or ALT) to merge visible to that new layer, the shot was flattened and sharpened using Un Sharp Mask. IR with architectural details seems to be able to take quite a lot of sharpening to crisp up those edges without looking over the top. The house and the wall really benefitted from the process. But the same cannot be said for the wispy clouds and smooth water, so I used added a mask and painted out the clouds and water, therefore revealing the other unsharpened layers underneath.

Save the whole thing as Jpeg and off to Flickr we go!!