Digital IR Image Processing

This quickie tutorial deals with processing your captured digital IR images in the highly acclaimed Adobe PhotoShop (version CS2).

I actually prefer to photograph (shoot) using the RAW format but for this brief lesson, I'll discuss the various steps on bringing your infrared image to life in the JPEG format, which, incidentally, is a compressed format.

Open your digital infra-red JPEG image in PhotoShop and if you think it looks a little 'flat', lacking a bit of punch, firstly go to the top toolbar and select 'image', followed by 'adjustments' and then select 'levels'.

You could select 'auto levels' and let your computer do the guess work however, I recommend 'levels' so that you have full control of how much contrast you want to bring into your digital IR image.

When you get into the 'levels' window, you'll see what is called a 'histogram' ... at this point, check that the 'channel' is set to RGB.

Just below the 'input levels' information, you'll see a black mass and 3 sliders directly beneath - make sure that you have 'preview' ticked (this allows you to see changes you make to your image whilst making any adjustments.

Select the black left slider and move across to the right until it falls just beneath the start of the curve above (black mass) ... do the same with the right white arrow but pulling in to the left and again, resting it just below where the curve appears - you should be able to see your contrast boosted image accordingly and you may play around until your hearts content to get the exact look you are aiming for.

If your digital images are false colour infrared images, you can change them to black and white by going to 'image', 'adjustments' and select 'desaturate' - hey presto.

If you want to keep colour in your image, ignore the previous command relating to adjusting to black and white and head for channel swapping - what?

Channel swapping or channel mixing when used on IR images is where you swap around the red and blue channels - i.e. you are effectively changing a red sky for a blue one as in infra-red, your scene is captured in shades of red.

Again, select 'image', 'adjustments' and then 'channel mixer' - ensure 'red' is selected as the 'output channel' and move the 'red' channel slider until it displays 0% and then move the 'blue' channel slider to read 100%.

Now set the 'output channel' to 'blue', move the 'blue' channel slider to show 0% and the 'red' channel slider to display 100% - click 'okay' and you should end up with a blue sky (fingers crossed).

To further enhance your infrared image, perhaps you want to tweak the false colour and saturation, go to 'adjustments', 'hue and saturation' and adjust accordingly - if you are anything like me, you can spend hours making little adjustments here and there until it is just perfect.

Last but not least, save your processed image.

TIP: Make a copy of your original JPEG before processing and making changes to your image.

CAUTION: JPEG files deteriorate with each modification - ensure you always keep the original in a safe place and make alterations to copies of your originals only.

RECOMMENDATION: Wherever and whenever possible, shoot RAW - this format, in the majority of cases, is not compressed and you can make many changes to the image without any deterioration.

Happy Processing

Jane Newman.co.uk