Photographie and Sound health

Infrared imaging is one type of photography that holds a little more promise. Although digital cameras include an infrared-blocking filter, or “hot mirror,” enough infrared light leaks through to make it possible to take pictures by the wavelengths that remain. You’ll need a special filter and long exposures, but infrared photography is entirely practical with a DSLR. Infrared photography is a “special project” exercise in my book Mastering Digital Photography, but I’m going to tell you everything you need to know here. But first, a warning as a DSLR owner, you’ll be shooting blind! As I mentioned earlier , because the infrared filters you’ll use block visible light, your optical viewfinder will appear to be totally black, and, of course, your LCD can’t be used for previewing pictures. Still, infrared pictures look cool because your subjects, particularly plant-life, absorb or reflect infrared light in proportions that are different from what you see with visible light. The tonal relationships can be wildly weird, with black skies and white foliage. People will appear pale and washed out, perhaps even ghastly. Indeed, because infrared photography is not particularly people-friendly, it’s most often used for landscapes and scenic photos. A side effect of infrared imaging is that the photos tend to look grainy and soft in focus, because of the different way in which your lens and camera handle IR illumination. Most of the time, you’ll want to convert your infrared images to grayscale, but some interesting color effects can be achieved, too. The picture here shows an infrared image that’s been converted to monochrome. You can also get some “color” infrared effects through a process known as channel swapping. After you’ve produced your infrared photo, apply your image editor’s auto-levels control to adjust tonal values. Then exchange the red and blue values by editing each of those two channels separately. In Photoshop, use the Channel Mixer to edit the Red channel, moving the Red slider to 0 percent and the Blue slider to 100 percent. Then, do the opposite to the Blue channel, changing its Red slider to 100 percent, and its Blue slider to 0 percent.