Notes On Composite Video Colors
Many of early video chips output composite video YPbPr colors, sometimes inaccurately referred as YUV colors. YUV is the color specification used for PAL TV systems, not for composite video; nevertheless, YPbPr and YUV share the same chroma axis in the color plane, so relative (not absolute) values are often interchangeable.
For the YPbPr cases, the color representations shown in this article, given in RGB, could be slightly inaccurate. Anyway, all conversions from YPbPr to RGB has been made at maximum possible saturation level while keeping the colors inside the RGB gamut (except where noted), so these colors seem to be less vivid than those actually seen on a monitor or TV with saturation set to a higher level.
All YPbPr values are given in an absolute scale from 0.0 to 1.0 for luminance (Y) and in a relative scale from -1.0 to 1.0 for the chroma (Pb and Pr). So, to convert to RGB you must multiply the Pb and Pr given values by the saturation (for example, if it is 56%, then use 0.56) and multiply again:
- a) by 0.5 (the Pb and Pr highest absolute value) if you use YPbPr-to-RGB formulae, or
- b) by 0.436 and 0.615 (U and V highest absolute values, respectively) if you use the YUV-to-RGB ones,
prior to perform the calculations.
Also, when seen on TV devices through an RF modulator, the perception of these colors may be not corresponding with the original YPbPr ones (most noticeable with NTSC TV color system, due to its YIQ color space plane is not one-to-one compatible with YPbPr and YUV).
Read more about this topic: List Of 8-bit Computer Hardware Palettes
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