Module Gg.Color

The type for colors in a device independent RGB color space with an alpha component. The color space is defined by a D65 white point and the ITU-R BT.709 primaries (corresponds to a linearized sRGB space). The alpha component represent the color's opacity ranging from 0., a fully transparent color, to 1. a completly opaque one.

The type for color stops. A piecewise linear color curve.

v r g b a is the linear sRGB color (r, g, b, a) as a color value.

v r g b ~a is the sRGB color (r, g, b, a) converted to a Gg color value.

v_srgbi r g b ~a is the 24-bit sRGB color (r, g, b, a) converted to a Gg color value by (v_srgb (float r /. 255.) (float g /. 255.) (float b /. 255.) ~a)

r c is the red component of c.

g c is the green component of c.

b c is the blue component of c.

a c is the alpha component of c.

void is (v 0. 0. 0. 0.) an invisible color.

black is (v 0. 0. 0. 1.)

gray a g is the sRGB color (g, g, g, a) converted to color a value.

white is (v 1. 1. 1. 1.)

red is (v 1. 0. 0. 1.)

green is (v 0. 1. 0. 1.)

blue is (v 0. 0. 1. 1.)

blend src dst is src blended over dst using source over destination alpha blending. See Alvy Ray Smith. Image compositing fundamentals. 1995.

clamp c is c with all components clamped to [0;1]. nan components are left untouched.

with_a c a is the same color as c but with the alpha component a.

The type for colors in the sRGB color space with an alpha component. This is the color space used, for example, by CSS.

of_srgb c is the sRGB color c as a Gg color.

to_srgb c is the Gg color c as a sRGB color.

to_srgbi c is the Gg color c as a 24-bit sRGB color (r, g, b, a), see v_srgbi.

The type for colors in the Oklab color space with an alpha component. The meaning and range of components is:

• L is the perceived lightness in the range 0. to 1.
• a is how green/red the color is, unbounded but typical range in -0.5 to 0.5
• b is how blue/yellow the color is, unbounded but typical range in -0.5 to 0.5

Note that euclidian distance between two oklab colors can be used as a perceptual color difference metric. A JND is a difference of 0.02 (ref).

of_oklab c is the Oklab color c as a Gg color.

to_oklab c is the Gg color c as an Oklab color.

The type for colors in the Oklch color space with an alpha component. This is a polar form of Oklab. The meaning and range of components is:

• L is the perceived lightness in the range 0. to 1.
• C is the chroma in the range 0. to unbounded but typically 0.5
• h is the hue in radians in the range 0. to 2pi.

of_oklch c is the Oklch color c as a Gg color.

to_oklch c is the Gg color c as an Oklch color.

The type for colors in the CIE L*u*v* color space with a D65 reference white point and an alpha component. The meaning and range of the components is:

• L* is lightness in the range 0. to 100.
• u*'s practical range is -134. to 220.
• v*'s practical range is -140. to 122.

of_luv c is the L*u*v* color c as a Gg color.

to_luv c is the Gg color c as a L*u*v* color.

The type for colors in the CIE L*C*h_uv color space with a D65 reference white point and an alpha component. This color space is CIE L*u*v* with polar coordinates, the meaning and range of the components is:

• L* is the lightness in the range 0. to 100.
• C* represents chroma, in the range 0. to 260.77 in practice.
• h represents hue in radians in the range 0. to 2pi.

of_lch_uv c is the L*C*h_uv color c as a Gg color.

to_lch_uv c is the Gg color c as a L*C*h_uv.

The type for colors in the CIE L*a*b* color space with a D50 reference white point and an alpha component. The meaning and range of the components is:

• L* is lightness in the range 0. to 100.
• a* and b*'s practical range is -128. to 127.

of_lab c is the L*a*b* color c as a Gg color value.

to_lab c is the Gg color c as a L*a*b* color.

The type for colors in the CIE L*C*h*_ab color space with a D50 reference white point and an alpha component. This color space is CIE L*a*b* with polar coordinates, the meaning and range of the components is:

• L* is the lightness in the range 0. to 100.
• C* represents chroma, in the range 0. to 181.02, but less in practice.
• h represents hue in degrees in the range 0. to 2pi.

of_lch_ab c is the L*C*h_ab color c as a Gg color.

to_lch_ab c is the Gg color c as a L*C*h_ab.

The type for color spaces. These correspond to the ICC v4 supported color space, see the specification, section 7.2.6.

space_dim s is the dimension of the color space s.

pp_space s prints a textual representation of s on ppf.

The type for ICC color profiles. A color profile can describe the characteristics of a color space, an input or output device and provide a mapping to a profile connection space (PCS), which is either CIE L*a*b* or XYZ with a D50 white point. For more information about ICC profile consult the ICC FAQ and the ICC v4 specification.

This module defines only a profile for the color space of color and a grayscale color space.

profile_of_icc s is a profile from the ICC profile byte stream s. None is returned if s doesn't seem to be a ICC profile.

Note A profile value is returned if a color space can be extracted, it doesn't guarantee a correct ICC profile byte stream.

profile_to_icc p is p's ICC profile byte stream.

profile_space p is p's color space.

profile_space p is space_dim (profile_space d).

p_gray_l is a linear gray color profile

p_rgb_l is the color profile of color values.