a) An additive color space with colorimetric coordinates based on red, green, and blue stimuli or primaries. Color values are negative in certain areas outside the gamut defined by the R, G, B primaries.

The R, G, B values used are intensities. b) The three linear video signals carrying respectively the red, the green, and the blue information. By convention, the unprimed symbols signify that there is a linear relationship between the luminance in each spectral region and the corresponding video signal. The spectral composition of the luminance forming each of these signals is one of the specifications required of the video system. The recently adopted CCIR Rec 709 reflects worldwide agreement on the current definition of R, G, B primary colors. CCIR Rec 709 identifies this as an interim agreement to be superseded by preferred primary colors encompassing a wider color gamut as soon as the technologies and practices permit. c) The colorimetric coordinates defined by thee nonlinear video signals carrying respectively the red, the green, and the blue information. By convention the primed symbols signify that there has been a nonlinear transformation of the video signals vs. luminance, relative, scene, with its resulting modification of the opto-electric transfer function.