Also known as color cast correction, it is a technical term in the post-production (darkroom technology already existing in the age of photographic film). Compared with “modulation” which has a vague concept, correction imposes far stricter requirements. Its purpose is to restore precisely the hue detected by human eyes on the shooting site; that’s what makes professional “correction” vastly different from “modulation”. Professional color correction represents a process that composites the frames shot on the site or generated in the later stage into a single, compound image. However, when different source materials are mixed, whether the unity among color, motion, perspective and material acuity could be achieved will directly affect the sense of reality and credibility of the work, and particularly, the processing of color, important expressive element of video image, will directly affect the artistry of film and TV representation.