GIMP Guru

SimulatedInfrared

Simulating Infrared Photography with The GIMP

Before After

In this tutorial I’ll show you how to simulate black and white infrared film. Infrared film is sensitive to both ultraviolet and infrared wavelength light. Green foliage reflects a lot of infrared light, which is why infrared film is often used to take “supernatural” landscapes. Cameras do not focus infrared light the same way they do visible light, which is one reason infrared photographs tend to be a little blurry. Black and white infrared film is also generally very sensitive (large grain), which is why B&W infrared photos look grainy.

The Procedure

Here is the original example image, loaded into The GIMP.
Step 1: convert the image to B&W. If you do a simple mode change to grayscale (Image/Mode/Grayscale), as I did here, be sure to change back to RGB mode (Image/Mode/RGB).Note: if you have the Channel Mixer plug-in, be sure to try it first. Try boosting the green channel significantly at the expense of red and blue (experiment to see what gives the best results for your particular image).
Step 2: follow the instructions for a Gaussian Blur Overlay, except set the layer blend mode to “Screen” instead of “Overlay”. A blur radius of 5-20 pixels, according to your preference, ought to do the trick.If the highlights are blown out after this, try any of the following:

  • (best) use Levels or Curves on the Blur Overlay layer.
  • (good) adjust the opacity of the Blur Overlay layer in the Layers dialog;
  • use a layer mask to protect the highlights, as described in the blur overlays tutorial (Note: this doesn’t seem to work as well with B&W images, at least for me).
Step 3 (optional): add some grain.Note: I wanted a strong grain effect, so I didn’t use a film grain layer mask.

That’s it!

Other Examples

The original image. Infrared.

Further Reading

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