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Module Gg.Color

module Color: sig .. end
Colors and color profiles.

Color provides some function to operate on color values and basic support for ICC based color profiles to precisely specify how to interpret raw color samples.

References.



Constructors, accessors and constants


type t = 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.
type stops = (float * Gg.color) list
The type for color stops. A piecewise linear color curve.
val v : float -> float -> float -> float -> Gg.color
v r g b a is the linear sRGB color (r, g, b, a) as a color value.
val v_srgb : ?a:float -> float -> float -> float -> Gg.color
v r g b ~a is the sRGB color (r, g, b, a) converted to a color value.
val v_srgbi : ?a:float -> int -> int -> int -> Gg.color
v_srgbi r g b ~a is the sRGB color (r,g,b,a) converted to a color value by (v_srgb (float r /. 255.) (float g /. 255.) (float b /. 255.) ~a)
val r : Gg.color -> float
r c is the red component of c.
val g : Gg.color -> float
g c is the green component of c.
val b : Gg.color -> float
b c is the blue component of c.
val a : Gg.color -> float
a c is the alpha component of c.
val void : Gg.color
void is (v 0. 0. 0. 0.) an invisible color.
val black : Gg.color
black is (v 0. 0. 0. 1.)
val gray : ?a:float -> float -> Gg.color
gray a g is the sRGB color (g, g, g, a) converted to color a value.
val white : Gg.color
white is (v 1. 1. 1. 1.)
val red : Gg.color
red is (v 1. 0. 0. 1.)
val green : Gg.color
green is (v 0. 1. 0. 1.)
val blue : Gg.color
blue is (v 0. 0. 1. 1.)

Functions


val blend : Gg.color -> Gg.color -> Gg.color
blend src dst is src blended over dst using source over destination alpha blending. See Alvy Ray Smith. Image compositing fundamentals. 1995.
val clamp : Gg.color -> Gg.color
clamp c is c with all components clamped to [0;1]. nan components are left untouched.
val with_a : Gg.color -> float -> Gg.color
with_a c a is the same color as c but with the alpha component a.

Color conversions

Note. In the following conversions all color spaces carry an alpha component. The alpha component is always left untouched by the conversions.

sRGB


type srgb = Gg.v4
The type for colors in the sRGB color space with an alpha component. This is the color space used, for example, by CSS.
val of_srgb : srgb -> Gg.color
of_srgb c is the sRGB color c as a Gg color.
val to_srgb : Gg.color -> srgb
to_srgb c is the Gg color c as a sRGB color.

CIE L*u*v*


type luv = Gg.v4
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: 
val of_luv : luv -> Gg.color
of_luv c is the L*u*v* color c as a Gg color.
val to_luv : Gg.color -> luv
to_luv c is the Gg color c as a L*u*v* color.

CIE L*C*huv


type lch_uv = Gg.v4
The type for colors in the CIE L*C*huv 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: 
val of_lch_uv : lch_uv -> Gg.color
of_lch_uv c is the L*C*huv color c as a Gg color.
val to_lch_uv : Gg.color -> lch_uv
to_lch_uv c is the Gg color c as a L*C*huv.

CIE L*a*b*


type lab = Gg.v4
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: 
val of_lab : Gg.v4 -> Gg.color
of_lab c is the L*a*b* color c as a Gg color value.
val to_lab : Gg.color -> Gg.v4
to_lab c is the Gg color c as a L*a*b* color.

CIE L*C*hab


type lch_ab = Gg.v4
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: 
val of_lch_ab : lch_ab -> Gg.color
of_lch_ab c is the L*C*hab color c as a Gg color.
val to_lch_ab : Gg.color -> lch_ab
to_lch_ab c is the Gg color c as a L*C*hab.

Color spaces


type space = [ `CLR2
       | `CLR3
       | `CLR4
       | `CLR5
       | `CLR6
       | `CLR7
       | `CLR8
       | `CLR9
       | `CLRA
       | `CLRB
       | `CLRC
       | `CLRD
       | `CLRE
       | `CLRF
       | `CMY
       | `CMYK
       | `Gray
       | `HLS
       | `HSV
       | `Lab
       | `Luv
       | `RGB
       | `XYZ
       | `YCbr
       | `Yxy ]
The type for color spaces. These correspond to the ICC v4 supported color space, see the specification, section 7.2.6.
val space_dim : space -> int
space_dim s is the dimension of the color space s.
val pp_space : Format.formatter -> space -> unit
pp_space s prints a textual representation of s on ppf.

Color profiles


type profile
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 Gg.color and a grayscale color space.

val profile_of_icc : string -> profile option
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.

val profile_to_icc : profile -> string
profile_to_icc p is p's ICC profile byte stream.
val profile_space : profile -> space
profile_space p is p's color space.
val profile_dim : profile -> int
profile_space p is space_dim (profile_space d).
val p_gray_l : profile
p_gray_l is a linear gray color profile
val p_rgb_l : profile
p_rgb_l is the color profile of color values.