rgbR

rgbR is a term used in color representation that refers to variants derived from the standard RGB color model. The exact meaning of rgbR varies by context, but it generally signals some emphasis on the red component or the inclusion of an additional red-related channel.

In some imaging pipelines, rgbR denotes a four-channel color model with channels labeled R, G, B, and R' (or an equivalent redundant red channel). The extra channel may be used for redundancy, error detection, or to store an alternative red-related value for tone mapping or high-dynamic-range compositing.

In color science and graphics, rgbR can also refer to a red-primary variant of RGB color spaces, where the primary color set is based on red rather than the standard primaries used for sRGB, with downstream channels derived accordingly. In software and shader contexts, rgbR may appear as a naming convention for color vectors or arguments that include a separate "red" component used for special processing.

Because rgbR is not a single standardized format, implementations and interpretations differ across projects; there is no widely adopted specification. When encountering rgbR, it is important to consult the relevant documentation to understand which channels are included and how they are encoded.

See also RGB, RGBA, color space, high dynamic range, color management.