README
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cie
CIE is the International Commission on Illumination which establishes standards for representing color information.
This package contains standard values and routines for converting between standard RGB color space (sRGB), and the the CIE standard color spaces of XYZ and Lab* (LAB).
XYZ color space (1931): standard color basis space
https://en.wikipedia.org/wiki/CIE_1931_color_space
Yis the luminance (overall brightness) = 0.2 red + 0.7 green + 0.07 blueZis purely the short wavelength (blue) = 0.02 red + 0.1 green + 0.95 blueXis a mix of the three CIE LMS cone responses chosen to be nonnegative: 1.9 long (red), -1.1 medium (green), and 0.2 short = 0.4 red + 0.36 green + 0.18 blue
The unit of the tristimulus values X, Y, and Z is often arbitrarily chosen so that Y = 1 or Y = 100 is the brightest white that a color display supports. In this case, the Y value is known as the relative luminance. The corresponding whitepoint values for X and Z can then be inferred using the standard illuminants.
LAB Lab* color space
https://en.wikipedia.org/wiki/CIELAB_color_space
lightness L*defines black at 0 and white at 100.a*is relative to the green–magenta opponent colors, with negative values toward green and positive values toward magenta.b*represents the blue–yellow opponents, with negative numbers toward blue and positive toward yellow.
The a* and b* axes are unbounded and depending on the reference white they can easily exceed ±150 to cover the human gamut. Nevertheless, software implementations often clamp these values for practical reasons. For instance, if integer math is being used it is common to clamp a* and b* in the range of −128 to 127.
CIELAB is calculated relative to a reference white, for which the CIE recommends the use of CIE Standard illuminant D65. D65 is used in the vast majority industries and applications, with the notable exception being the printing industry which uses D50.
Documentation
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Index ¶
- Variables
- func LABCompress(t float32) float32
- func LABToXYZ(l, a, b float32) (x, y, z float32)
- func LABUncompress(ft float32) float32
- func LToY(l float32) float32
- func SRGB100ToLinear(r, g, b float32) (rl, gl, bl float32)
- func SRGBFloatToUint32(rf, gf, bf, af float32) (r, g, b, a uint32)
- func SRGBFloatToUint8(rf, gf, bf, af float32) (r, g, b, a uint8)
- func SRGBFromLinear(rl, gl, bl float32) (r, g, b float32)
- func SRGBFromLinear100(rl, gl, bl float32) (r, g, b float32)
- func SRGBFromLinearComp(lin float32) float32
- func SRGBLinToXYZ(rl, gl, bl float32) (x, y, z float32)
- func SRGBToLinear(r, g, b float32) (rl, gl, bl float32)
- func SRGBToLinearComp(srgb float32) float32
- func SRGBToXYZ(r, g, b float32) (x, y, z float32)
- func SRGBToXYZ100(r, g, b float32) (x, y, z float32)
- func SRGBUint32ToFloat(r, g, b, a uint32) (fr, fg, fb, fa float32)
- func SRGBUint8ToFloat(r, g, b, a uint8) (fr, fg, fb, fa float32)
- func XYZ100ToSRGB(x, y, z float32) (r, g, b float32)
- func XYZDenormD65(x, y, z float32) (xr, yr, zr float32)
- func XYZNormD65(x, y, z float32) (xr, yr, zr float32)
- func XYZToLAB(x, y, z float32) (l, a, b float32)
- func XYZToSRGB(x, y, z float32) (r, g, b float32)
- func XYZToSRGBLin(x, y, z float32) (rl, gl, bl float32)
- func YToL(y float32) float32
Constants ¶
This section is empty.
Variables ¶
var WhiteD50 = math32.Vec3(96.4212, 100.0, 82.5188)
WhiteD50 is the standard white color used for printing industry, D50, in XYZ coordinates.
var WhiteD65 = math32.Vec3(95.047, 100.0, 108.883)
WhiteD65 is the standard white color for midday sun, D65, in XYZ coordinates. Used as a standard reference illumination condition for most cases.
Functions ¶
func LABCompress ¶
LABCompress does cube-root compression of the X, Y, Z components prior to performing the LAB conversion
func LABToXYZ ¶
LABToXYZ converts a color from L*a*b* to XYZ coordinates using the standard D65 illuminant
func LABUncompress ¶
func LToY ¶
LToY Converts an L* value to a Y value. L* in L*a*b* and Y in XYZ measure the same quantity, luminance. L* measures perceptual luminance, a linear scale. Y in XYZ measures relative luminance, a logarithmic scale.
func SRGB100ToLinear ¶
SRGB100ToLinear converts set of sRGB components to linear values, removing gamma correction. returns 100-base RGB values
func SRGBFloatToUint32 ¶
SRGBFloatToUint32 converts the given non-alpha-premuntiplied sRGB float32 values to alpha-premultiplied sRGB uint32 values.
func SRGBFloatToUint8 ¶
SRGBFloatToUint8 converts the given non-alpha-premuntiplied sRGB float32 values to alpha-premultiplied sRGB uint8 values.
func SRGBFromLinear ¶
SRGBFromLinear converts set of sRGB components from linear values, adding gamma correction.
func SRGBFromLinear100 ¶
SRGBFromLinear100 converts set of sRGB components from linear values in 0-100 range, adding gamma correction.
func SRGBFromLinearComp ¶
SRGBFromLinearComp converts an sRGB rgb linear component to non-linear (gamma corrected) sRGB value Used in converting from XYZ to sRGB.
func SRGBLinToXYZ ¶
SRGBLinToXYZ converts sRGB linear into XYZ CIE standard color space
func SRGBToLinear ¶
SRGBToLinear converts set of sRGB components to linear values, removing gamma correction.
func SRGBToLinearComp ¶
SRGBToLinearComp converts an sRGB rgb component to linear space (removes gamma). Used in converting from sRGB to XYZ colors.
func SRGBToXYZ100 ¶
SRGBToXYZ100 converts sRGB into XYZ CIE standard color space with 100-base sRGB values -- used for CAM16 but not CAM02
func SRGBUint32ToFloat ¶
SRGBUint32ToFloat converts the given alpha-premultiplied sRGB uint32 values to non-alpha-premuntiplied sRGB float32 values.
func SRGBUint8ToFloat ¶
SRGBUint8ToFloat converts the given alpha-premultiplied sRGB uint8 values to non-alpha-premuntiplied sRGB float32 values.
func XYZ100ToSRGB ¶
XYZ100ToSRGB converts XYZ CIE standard color space, 100 base units, into sRGB
func XYZDenormD65 ¶
XYZDenormD65 de-normalizes XZY values relative to the D65 outdoor white light values
func XYZNormD65 ¶
XYZNormD65 normalizes XZY values relative to the D65 outdoor white light values
func XYZToLAB ¶
XYZToLAB converts a color from XYZ to L*a*b* coordinates using the standard D65 illuminant
func XYZToSRGBLin ¶
XYZToSRGBLin converts XYZ CIE standard color space to sRGB linear
Types ¶
This section is empty.
Source Files