Infrared (IR) light lies between the visible spectrum and radio waves. It is invisible to the naked eye, but camera sensors are sensitive to it (to a degree). Therefore special IR filters can be purchased, but these greatly extend exposure time, because the IR filter greatly reduces light waves hitting the sensor.
There are three ways to take IR images. Firstly, you can convert your camera. This procedure is expensive, and once converted, only IR images can be produced. This option is only for a serious IR enthusiast.
Secondly, you can buy special infrared film. This is also expensive, and requires extremely careful special handling. Also, it can obviously only be used with film cameras!
Lastly, and most beneficially for the common photographer, IR filters can be purchased. Of course, these do have their own price tag, which is usually not small, but in the long term, they are the most pocket friendly!
You can also apply an IR effect to an existing digital photograph. Below I will show you how.
Begin by opening your image in Adobe Photoshop CS. I am using CS5 extended, but you should be able to use anything from CS 2 or 3 up.
Select your image layer, and go to image > duplicate or use Cmd/Ctrl + J.
Next, press Ctrl + I to invert the image. You should have something like this…
Now your image should have a (not so!) lovely orange/brown and blue/purple tone. Next step is to change the blending mode of the layer to ”color”.
The next step is to got to Layer > New Adjustment Layer > Channel mixer or select the tri-coloured icon from the adjustments panel. This opens the channel mixer.
Select ”red” then move the red slider to 0 and the blue one to +100. Do the reverse on the ”blue” channel. Ensure the green slider is on ”green” +100.
This next step involves hue/saturation. It will vary depending on the image you use, the main principle remains the same: we need to convert the purple/red areas to blue/white.
- Move the Saturation slider till the image is almost grey
- Move hue slider to add a hint of yellow
- Lightness to around +50