Infrared light is the part of the spectrum that ranges between 700nm to 900nm. We are not able to see this light so infrared photography can be quite challenging to say the least. In the good old days of film photography, one could purchase Kodak´s wonderful High speed HIE film to take true infrared images. The film had no normal ISO rating so exposure had to be bracketed and you had to use a special infrared filter for a proper effect. You also had to load and unload film in complete darkness to avoid fogging the film as it was extremely sensitive to infrared light.
Nowadays, in the digital era of photography, you can have an old digital SLR converted to take infrared images but you would need long exposures making it difficult for handheld shots. This conversion can be expensive and you would not be able to take normal pictures as before once the camera is converted. An infrared filter is also a must. I´m going to show you two easy ways of achieving an infrared image without all the complicated gear.
The first thing I want to cover is choosing the right image for this effect. Not all photographs look good in infrared. The main caracteristics of the effect is a dreamlike appearance caused mainly by foliage reflecting infrared light. This foliage is usually contrasted by dark skies that absorb infrared light. Another caracteristic, mainly of the Kodak film mentioned before, is the formation of a strong glow or blooming around the highlights that helps emphasize the lurid appearance caused by the absence of an anti-halation layer on the film.
When choosing your image make sure there are lots of trees and bushes to create a glow. Also make sure the sky is as dark as possible by use of a polarizing filter or simply darkening it with Photoshop. You might want to include a subject that will not reflect infrared light as a point of interest (a trail in a forest, a house, etc).
The easiest way of achieving an infrared effect in Photoshop is by simply using the B&W Adjustment Layer in your layers palette. You can access it by going to the bottom of the layers palette and selecting “create new fill or adjustment layer”.
This will bring up the Black and White conversion window from where you can choose a variety of predefined adjustments that simulate different photo filters. Choose the infrared setting. Now, depending on your image, you can modify the values of different colors and how they will translate to black and white accordingly. In my image I had a lot of yellow and with the default value I lost a lot of detail in the highlights so I had to pull those back a bit. Furthermore, my sky was not dark enough so I decided to tweak the Cyans and the Blues. This will depend entirely on you and the image you have chosen.
This quick step by adding some grain texture would be pretty much done but we would be missing a critical ingredient. What about those dreamy glows? If you want to add the blooming effect than we will have to take a different approach. Get rid of that previous adjustment layer (or simply make it invisible of you want to keep it around) and copy your background layer by simply dragging it onto the New Layer icon at the bottom of your layers palette. Call this layer “Infrared”.
With this layer selected go to your channels palette (it should be next to your layers palette) and select your green channel. What we´re going to do to this channel is blur it using Filter > Blur > Gaussian Blur..
In the Gaussian Blur window you can set how much blur you want to add to this channel. You want to blur but try not to go overboard. If you can still make out the image that should be enough. In my case, because it´s a small image for the web, a radius of 4 pixels was good enough. For a large image you might go as high as 15px.
Remember your image is still in color. We´re just looking at the green channel. To convert it to black and white this time we´ll use the Channel Mixer Adjustment Layer.
In the Channel Mixer window the first thing we need to do is to check where it says Monochrome. This will convert our image to black and white. Because we want the foliage to seem as if it´s reflecting infrared light we want the green channel to increase +200%. To compensate (The total of the three channels must add up 100%) we´re going to drop both the red and the blue channel to -50%
Now when you go back to you image you will notice that the overall effect is way too much. Your highlights will be completely washed up. Don´t worry. What we have to do to recover those details is to go back to your layer marked Infrared and drop the opacity level on it. Again, this will depend on your image. In my case I gave this layer an opacity of 40%.
The last thing we want to do to really give the appearance of infrared film is to add some film grain. In digital images this comes in the form of noise. Merge all your layers in a fresh new layer by pressing SHIFT + CTR + ALT + E and call this layer “Grain”. Next, go to Filter > Noise > Add Noise. In my case, with an amount of 5% I´m fine but if your image is large you will probably need a higher amount. Just make sure it´s subtle not overpowering. Also make sure to check monochromatic to avoid colored grain and to select Gaussian in the Distribution Box for a more natural looking grain texture.
That´s all there is to it! Hope you found this tutorial useful. Here´s the before and after pictures to see how they compare: