rgbwide2xyz

Convert wide-gamut RGB color values to CIE 1931 XYZ color values

Syntax

XYZ = rgbwide2xyz(RGB,BPS)

XYZ = rgbwide2xyz(RGB,BPS,Name,Value)

Description

XYZ = rgbwide2xyz(RGB,BPS) converts wide-gamut RGB values in the BT.2020 or BT.2100 color spaces to CIE 1931 XYZ color values. BPS specifies the number of bits required to represent each input channel.

XYZ = rgbwide2xyz(RGB,BPS,Name,Value) specifies options using one or more name-value pair arguments.

Examples

Convert Wide-Gamut RGB Values to CIE 1931 XYZ Values

Convert 10-bit or 12-bit wide-gamut RGB color values in the BT.2020 or BT.2100 color spaces to CIE 1931 XYZ color values.

Convert 10-bit BT.2020 RGB Green Value to XYZ

Create a wide-gamut RGB value for the color green.

rgbvalue = uint16([64 940 64]);

Convert the 10-bit BT.2020 RGB color value to an XYZ color value.

xyzvalue = rgbwide2xyz(rgbvalue,10);

Convert 12-bit BT.2100 RGB Blue Value to XYZ

Create a wide-gamut RGB color value for the color blue.

rgbvalue = uint16([64 64 940]);

Convert the 12-bit BT.2100 RGB value to an XYZ color value.

xyzvalue = rgbwide2xyz(rgbvalue, 12,'ColorSpace','BT.2100');

Convert 10-bit BT.2100 RGB White Value to XYZ Using HLG

Create a wide-gamut RGB value for the color white.

rgbvalue = uint16([940 940 940]);

Convert the 10-bit BT.2100 RGB color value to an XYZ color value, using the Hybrid Log Gamma (HLG) transfer function.

xyzvalue = rgbwide2xyz(rgbvalue,10,'ColorSpace','BT.2100','LinearizationFcn','HLG');

Input Arguments

RGB — Wide-gamut RGB color values

p-by-3 | m-by-n-by-3 numeric array | m-by-n-by-3-by-f numeric array

Wide-gamut RGB color values, specified as one of the following:

• p-by-3 numeric matrix of color values (one color per row)

• m-by-n-by-3 numeric array representing an image

• m-by-n-by-3-by-f numeric array representing a stack of images

The following table shows the data range for wide-gamut, integer color values for 10- and 12-bit data. The minimum value in the range maps to black, and the maximum value in the range maps to white. Only pixels with RGB values within the supported data range for wide-gamut values are guaranteed to be mapped to realizable colors.

Data Type	Full Data Range	Data Range for Wide-Gamut RGB
10-bit	[0, 1023]	[64, 940]
12-bit	[0, 4095]	[256, 3760]

Data Types: uint16

BPS — Bits per sample for each channel of input image

10 | 12

Bits per sample for each channel of the input image, specified as the numeric scalar 10 or 12.

Data Types: single | double | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64

Name-Value Pair Arguments

Specify optional comma-separated pairs of Name,Value arguments. Name is the argument name and Value is the corresponding value. Name must appear inside quotes. You can specify several name and value pair arguments in any order as Name1,Value1,...,NameN,ValueN.

Example: xyzvalue = rgbwide2xyz(rgbvalue,12,'ColorSpace','BT.2100');

'ColorSpace' — Color space of wide-gamut RGB values

'BT.2020' (default) | 'BT.2100'

Color space of the wide-gamut RGB values, specified as the comma-separated pair consisting of 'ColorSpace' and the value 'BT.2020' or 'BT.2100'.

Data Types: char | string

'WhitePoint' — Reference white point

'd65' (default) | 'a' | 'c' | 'd50' | 'd55' | 'icc' | 'e' | 3-element row vector

Reference white point, specified as the comma-separated pair consisting of 'WhitePoint' and a 3-element row vector, or any of the values in this table.

Value	White Point
'a'	CIE standard illuminant A, [1.0985, 1.0000, 0.3558]. Simulates typical, domestic, tungsten-filament lighting with correlated color temperature of 2856 K.
'c'	CIE standard illuminant C, [0.9807, 1.0000, 1.1822]. Simulates average or north sky daylight with correlated color temperature of 6774 K. Deprecated by CIE.
'e'	Equal-energy radiator, [1.000, 1.000, 1.000]. Useful as a theoretical reference.
'd50'	CIE standard illuminant D50, [0.9642, 1.0000, 0.8251]. Simulates warm daylight at sunrise or sunset with correlated color temperature of 5003 K. Also known as horizon light.
'd55'	CIE standard illuminant D55, [0.9568, 1.0000, 0.9214]. Simulates mid-morning or mid-afternoon daylight with correlated color temperature of 5500 K.
'd65'	CIE standard illuminant D65, [0.9504, 1.0000, 1.0888]. Simulates noon daylight with correlated color temperature of 6504 K.
'icc'	Profile Connection Space (PCS) illuminant used in ICC profiles. Approximation of [0.9642, 1.000, 0.8249] using fixed-point, signed, 32-bit numbers with 16 fractional bits. Actual value: [31595,32768, 27030]/32768.

Data Types: single | double | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64 | logical | char | string

'LinearizationFcn' — Transfer function for transformation

'PQ' (default) | 'HLG'

Transfer function for transformation, specified as the comma-separated pair consisting of 'LinearizationFcn' and either of these values:

Value	Description
'PQ'	Perceptual Quantization
'HLG'	Hybrid Log Gamma

Data Types: char | string

Output Arguments

XYZ — Values in CIE 1931 XYZ color space

numeric array

Values in the CIE 1931 XYZ color space, returned as a numeric array, of the same dimensions as the RGB input value, of class double.

Data Types: double

References

[1] Rec. ITU-R BT.2020-2 (10/2015), Parameter values for ultra-high definition television systems for production and international programme exchange.International Telecommunication Union; Broadcasting service (television). https://www.itu.int

[2] Rec. ITU-R BT.2100-2 (07/2018), Image parameter values for dynamic range television for use in production and international programme exchange.International Telecommunication Union; Broadcasting service (television).https://www.itu.int

[3] Rec. ITU-R BT.2390-7 (07/2019), High dynamic range television for production and international programme exchange.International Telecommunication Union; Broadcasting service (television). https://www.itu.int