What is color correction?

Answer 1

Color correction is commonly used in television production and image editing. A television image is made of red, green and blue images which make a full color image. Color correction is the technique that is used to adjust the colors to change the hue of the image. Sometimes it is used to remove color casts caused by lighting of the original scene; daylight, tungsten and fluorescent lighting are all different colors and if the camera is not set up for specific lighting conditions, the whole image can have a red, green or blue appearance. Other use include making changes for dramatic effect. Color correction includes several adjustments. Each adjustment can normally be applied to a single color or all three colors equally. First, the level of a color can be raised or lowered by a fixed amount regardless of the original intensity. Next, the gain of a color can be adjusted. This is like a contrast control on a television, so by increasing the gain, the lighter parts of an image become even lighter and the darker parts are made even darker. Lastly, a gamma control allows certain levels of intensity to be adjusted for each color. Gamma control allows, for example, darker portions of an image to be lightened to enhance the detail without changing the brighter parts of the image. As an example, an image may be used as a background for text to be overlaid. Leaving the image in its original form will make the text hard to read so it is quite common to reduce the contrast of the image, reducing the light portions and increasing the dark portions to wash out the image. Perhaps a color wash may be applied, so increasing the blue level will turn the whole image into a blue faded image. North American televisions once had a hue control along with brightness and contrast controls. This was another form of color correction used to compensate for timing drift in the NTSC color decoding process. As televisions have improved, the hue control is rarely used but can still be found on older models.