3.31. Infrared black and white

We can't see the infrared part of the light spectrum, but it can be recorded on special film or by digital sensors. Pioneered by the scientist Robert Wood, infrared film was commercially available from the 1930s. Minor White worked with it in the 1950s, but infrared really grew in popularity in the 1980s with specialists such as Simon Marsden and Anton Corbijn, whose album cover for U2's The Unforgettable Fire became a classic image of the period. While color infrared film is available, black and white has always been prized for producing near-black skies, clearly defined clouds, and shimmering, bright foliage. While some digital cameras can record near-infrared light, it is also possible to simulate infrared in the digital darkroom.

People always notice the unnatural tonal balance of infrared picturesthat is part of its great attraction. Trees, grass, and other plants are exceptionally bright because the chlorophyll reflects infrared light. Blues, such as those in the sky, are rendered as black, and haze is eliminated by the deep red lens filter that photographers used to cut out the visible spectrum. While grain is obvious, it is less so with some modern infrared films. The key to imitating infrared photography is to identify and convert foliage to black and white independent of other image areas.

Using Color Balance, as in step 2, is good with foliage and skies with good cloud formations. This picture also has many leavescomplicated shapes which would be difficult to select using the Lasso or Marquee tools, but well suited to this method.

To test whether your digital camera can capture infrared light directly, make a long exposure in a darkened room and fire an infrared remote control while the shutter is open. If it records an image, you can shoot infrared if you have an infrared filter for your camera.

Prepare the color image by saturating the blues and greens, making them easier to sample. Add a Selective Color adjustment layer, select Blue from the Colors drop-down box, and then drag the Black slider to the right. Do the same for Cyan and Green, and click OK. Selecting the foliage is the most important step. You can Ctrl/Cmd + click the Green channel in the Channels palette, or use the Lasso or Marquee to select trees and grass. Here the image has lots of small leaves, so it is better to use Color Range. Ensure the image layer is active, then use the Eyedropper tool (I) to sample a foliage green, and choose Select > Color Range. Refine the preview using the eyedroppers to add and subtract other foliage tones, adjust the Fuzziness slider until you have selected the foliage, and click OK. Sometimes the selection needs fine-tuning with the Lasso, but whenever you use the Lasso or other selection tools, make sure you feather the selection (this is not necessary if you only use Color Range). With the selection's "marching ants" visible, activate the Selective Color layer, Alt/Opt + Shift + click the "Create new fill or new adjustment layer" icon and select Channel Mixer. Name the layer "Channel MixerGreen". Check the Monochrome checkbox, set Green to 200%, and one or both of the remaining sliders to the left so that the three percentages add up to 100% (allowing for the negatives). The foliage should now be very bright. Duplicate the Channel Mixer adjustment layer with Red set to 200%, and Blue at -100%, a combination that makes blue skies black. If the combined values of the sliders add up to 100%, the adjustment will have no effect on the overall image brightness. Film grain should be added on its own layer. Hold down the Alt/Opt key as you click the "Create a new layer" icon, name it Grain, set the blending mode to Overlay, and tick the "Fill with Overlay-neutral color" checkbox. Reset Photoshop's foreground and background colors to black and white (D) and choose Filter > Artistic > Film Grain. Actual infrared film grain varies with film type and development, so there is no single correct setting. The settings shown are a good starting point, but if you don't like the result, undo it and experiment with other combinations. For the foliage's infrared glow, duplicate the image layer with Alt/Opt + Ctrl/ Cmd + J. Name the layer "Glow" and set the blending mode to Lighten. The glow radiates off foliage. This is already identified by the mask on the adjustment layer Channel MixerGreen. So, without actually activating that adjustment layer, Ctrl/Cmd + Click its mask in the Layers palette so you see the "marching ants." Then click the "Add a layer mask icon" to add an identical layer mask to the Glow layer. Click the Glow layer's thumbnail (be sure to click on the image thumbnail, not the mask), and select Filter > Gaussian Blur. Apply a small blur of 510 pixels. Infrared black-and-white pictures are often described as ghostly or otherworldly. Some digital cameras can shoot infrared, but imitating the dark skies and radiant foliage is easy in Photoshop.