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White balance adjustment is to adjust the light in a photo to white. In order to accomplish this one must have some neutrals in the image like a gray card or a white sheet of paper. Software can correct white balance, but not all software solutions are equally good. The first thing you might like to take care of, when you set out to retouch your photos, is white balance. White balance refers to the color of the light and assumes that the optimal light color is white. Some photos, like sunset or candlelight, do not have white light, but usually an impression of white light is good. Some use Photoshop's auto levels to set white balance, but that is not ideal, since auto levels only sets the brightest pixels to white and the darkest pixels to black without looking at the mid tones. But what if the brightest pixel in your photo is not white? Or what if you do not have pure black in the photo? (Most images have black areas, but the brightest pixel is rarely pure white). The mid tones are the most important and to help set the mid tones correctly one adds a grey card to the image when taking the photo. A grey card is a flat piece of cardboard or plastic colored an exact mid tone neutral gray. Ideally one has three cards: a black, a gray and a white. Photoshop's levels adjustment panel has three color pickers for picking color: one for white, one for gray and one for black. By clicking the gray color picker on the gray card, one can adjust the mid tones to neutral gray. One can of course only include a gray card in the picture if one intends later to crop the picture. If one does not want a gray card in the picture, or if one doesn't have a gray card , one can later use dedicated software that scans the image and calculates the color of the light and sets it to white. There are problems with such software: what if there are no neutral areas in the image to deduct the color of the light from? Some applications do not need a neutral in the picture, but most do to get a good result. If you work with RAW images, you will have found that the RAW converters normally come with a slider for color temperature, which means a slider to adjust the picture cool or warm. But what if the color of the light is greenish as when you have taken a picture in fluorescent light? The cool-warm control is good for regular incandescent light, but not for fluorescent. Color adjustment controls are never good for correcting white balance, because the color correction will not just neutralize the gray card, but will also color the picture in an undesirable way: often the blacks get colored or the whites or both. In short one needs some neutrals in an image to set white balance. A white wall or a sheet of white paper will do well; preferably also a gray card for the mid tones. Find out more at: Powerretouche Photoshop plugins
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White balance, photography, photo retouching, photo software,
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