Saturday, December 6, 2008

My experience with digital IR photography

When I first got my Sony F717 camera in 2002, I experimented with infrared photography simply because this camera is particularly well suited for IR (infrared) work. The F717's nightshot feature is designed to capture IR images in the dark. Used in broad daylight, visible light is screened out by using a Hoya R72 IR filter. On top of that, an ND8 filter reduces the amount of exposure. IR light is then captured by the IR-sensitive CCD sensor of the digital camera. Post processing turns a bland IR image into a more interesting coloured image. The above picture is my first attempt on coloured IR.

How to produce coloured IR: With a Hoya R72 IR filter, the image is heavily tinted in red/magenta (although not visible in the Jpeg image). The idea is to correct this by swapping red and blue channels. Using the Photoshop channel mixer, select the RED setting and set Red to 0% and Blue to 100%. Likewise, in the BLUE setting, set Blue to 0% and Red to 100%. Next, select Auto Color. If desired, you can adjust the saturation in the Hue/Saturation setting, or experiment with the Levels and Curves settings. Below are an IR image before and after post processing using Irfanview (which can also do the job).

For details on Digital IR Photography, see:
For quick tutorial, see:

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