Color Grading

Color grading is the process of altering and enhancing the color of a motion picture, video image, or still image either electronically, photo-chemically or digitally. The chemical process is also referred to as color timing and is typically performed at a photographic laboratory. Modern color correction, whether for theatrical film, video distribution, or print is generally done digitally in a color suite.

Primary and secondary color correction

Primary color correction affects the whole image utilizing control over intensities of red, green, blue, gamma (mid tones), shadows (blacks) and highlights (whites) of the entire frame. Secondary correction is based on the same types of processing used for Chroma Keying to isolate a range of color, saturation and brightness values to bring about alterations in luminance, saturation and hue in only that range, while having a minimal or usually no effect on the remainder of the color spectrum. Using digital grading, objects and color ranges within the scene can be isolated with precision and adjusted. Color tints can be manipulated and visual treatments pushed to extremes not physically possible with laboratory processing. With these advancements, the color correction process became increasingly similar to well-established digital painting techniques and ushered forth a new era of digital cinematography. 

Masks, Mattes, Power Windows

The evolution of digital color correction tools advanced to the point where the colorist could use geometric shapes (like mattes or masks in photo software such as Photoshop) to isolate color adjustments to specific areas of an image. These tools can highlight a wall in the background and color only that wall—leaving the rest of the frame alone—or color everything but that wall. Subsequent color correctors (typically software-based) have the ability to use spline-based shapes for even greater control over isolating color adjustments. Color keying is also used for isolating areas to adjust.

Inside and outside of area-based isolations, digital filtration can be applied to soften, sharpen or mimic the effects of traditional glass photographic filters in nearly infinite degrees.