White balance adjustment means to adjust the light in a picture to white. In order to do this one must have some neutrals in the image like a gray card or a white sheet of paper. Software can adjust white balance, but not all software solutions are equally good.
The first thing you want to address, when you begin to retouch your photos, is white balance. White balance refers to the color of the light and implies that the optimal light color is white. Some pictures, like sunset or candlelight, do not have white light, but in general an impression of white light is the best. Some use Photoshop's auto levels to set white balance, but that is not the best, since auto levels merely sets the darkest areas to black and the brightest to white without looking at the mid tones. But what if the lightest 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 lightest pixels are rarely pure white).
When correcting white balance, the mid tones are the most important and to help set the mid tones correctly one adds a grey card to the picture 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 image.
If one doesn't want a gray card in the picture, or if one does not have a gray card , one can later use specialized software that scans the image and calculates the color of the light and sets it to white. There are problems with such applications: what if there are no neutral areas in the photo to calculate the color of the light from? Some applications do not need a neutral in the picture, but most do to get a good result.
When working with RAW images, you will have discovered that the RAW converters usually come with a control for color temperature, which means a control to adjust the image cool or warm. But what if the color of the light is greenish as when you have taken a picture in neon light? The cool-warm slider is good for regular incandescent light, but not for fluorescent.
Color adjustment controls are rarely good for correcting white balance, because the color correction will not only neutralize the gray card, but will also tone the picture in an undesirable way: often the blacks get toned or the whites or both. In short one needs some neutrals in an image to adjust white balance. A white wall or a sheet of white paper will do well; preferably add a gray card for the mid tones.
The first thing you want to address, when you begin to retouch your photos, is white balance. White balance refers to the color of the light and implies that the optimal light color is white. Some pictures, like sunset or candlelight, do not have white light, but in general an impression of white light is the best. Some use Photoshop's auto levels to set white balance, but that is not the best, since auto levels merely sets the darkest areas to black and the brightest to white without looking at the mid tones. But what if the lightest 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 lightest pixels are rarely pure white).
When correcting white balance, the mid tones are the most important and to help set the mid tones correctly one adds a grey card to the picture 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 image.
If one doesn't want a gray card in the picture, or if one does not have a gray card , one can later use specialized software that scans the image and calculates the color of the light and sets it to white. There are problems with such applications: what if there are no neutral areas in the photo to calculate the color of the light from? Some applications do not need a neutral in the picture, but most do to get a good result.
When working with RAW images, you will have discovered that the RAW converters usually come with a control for color temperature, which means a control to adjust the image cool or warm. But what if the color of the light is greenish as when you have taken a picture in neon light? The cool-warm slider is good for regular incandescent light, but not for fluorescent.
Color adjustment controls are rarely good for correcting white balance, because the color correction will not only neutralize the gray card, but will also tone the picture in an undesirable way: often the blacks get toned or the whites or both. In short one needs some neutrals in an image to adjust white balance. A white wall or a sheet of white paper will do well; preferably add a gray card for the mid tones.
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