Invalid Colors

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Invalid colors aka “Illegal colors” refers to television colors that can not be turned into positive values of red, green and blue primaries in the  colour space they are intended for. Invalid colors may be generated by the colorimetry matrix in a camera or when mapping images from one color space to another, or as the result of image processing. For example, reducing  luminance in a high intensity blue or adding luminance to a strong yellow in a paint system based on YCbCr may send a subsequent RGB video value too high or low, producing at least inferior results and possibly causing technical problems. All combinations of RGB can be matrixed to YCbCr but not all combinations of YCbCr can be converted into valid RGB.

Out-of- RGB gamut detectors can be used to warn of these arrors. Most broadcasters and media publishers have contractual standards for technical and editorial quality and most reject material with invalid colours outside of specific tolerances.