TABLE 7 Classification of methods to expand the colour gamut of image systems Approach Name Description Performance Implementation and compatibility Display referred Negative RGB Use negative or more than unity values Considerably wide, but not all in Easy implementation of relatively approach for RGB while using conventional RGB some case, part of the area within circuitry in mixed environment with primaries colour will be covered current systems e.g. Recommendation ITU-R BT.1361, Optimal code efficiency may be Some standard or guideline that xvYCC difficult describes a real colour gamut expanded display may still be needed* Incompatibility with signal processing Wider RGB Use widened RGB primaries comprising Considerably wide, but not all, part No conversion circuitry is required (real colour) real colours of the area within colour locus will display compliant with the standard is be covered introduced e.g. Adobe RGB Code usage efficiency is expected to be high Wider RGB Use widened RGB primaries including Flexible choice as to cover the target Some conversion circuitry is needed at (imaginary imaginary colour(s) gamut (e.g. real surface colours) display end colour) e.g. [Input, 10] (Korea) Small efficiency drop due to the * See above coverage of outside part of colour locus XYZ based Use XYZ colorimetry and converted Any signal falling onto colour locus Some conversion circuitry is needed at primaries for transmission if needed is covered display end e.g. [Input, 53] (USA), Code efficiency is not expected * See above SMPTE 4281-2006 to be high Scene referred Multiple (more Use more than three primaries, spectral Environment-independent Completely different system approach than three) distribution reproduction ultimately reproduction primaries
TABLE 7 Classification of methods to expand the colour gamut of image systems Approach Name Description Performance Implementation and compatibility Display referred approach Negative RGB Use negative or more than unity values for RGB while using conventional RGB primaries e.g. Recommendation ITU-R BT.1361, xvYCC Considerably wide, but not all in some case, part of the area within colour will be covered Optimal code efficiency may be difficult Easy implementation of relatively circuitry in mixed environment with current systems Some standard or guideline that describes a real colour gamut expanded display may still be needed* Incompatibility with signal processing Wider RGB (real colour) Use widened RGB primaries comprising real colours e.g. Adobe RGB Considerably wide, but not all, part of the area within colour locus will be covered Code usage efficiency is expected to be high No conversion circuitry is required display compliant with the standard is introduced Wider RGB (imaginary colour) Use widened RGB primaries including imaginary colour(s) e.g. [Input, 10] (Korea) Flexible choice as to cover the target gamut (e.g. real surface colours) Small efficiency drop due to the coverage of outside part of colour locus Some conversion circuitry is needed at display end * See above XYZ based Use XYZ colorimetry and converted primaries for transmission if needed e.g. [Input, 53] (USA), SMPTE 4281-2006 Any signal falling onto colour locus is covered Code efficiency is not expected to be high Some conversion circuitry is needed at display end * See above Scene referred approach Multiple (more than three) primaries Use more than three primaries, spectral distribution reproduction ultimately Environment-independent reproduction Completely different system