laba
CIE 1976 LAB colors

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<laba> ( l a b alpha -- laba )

Vocabulary
colors.lab

Class description
The class of CIE 1976 LAB (commonly called CIELAB) colors with an alpha channel.

Definition

IN: colors.lab

TUPLE: laba l a b alpha ;

Methods

USING: accessors colors.lab colors.lch kernel locals.backend
math math.functions math.libm ;

M: laba >LCHab
    [
        [ l>> ] [ a>> ] [ b>> ] tri 3 load-locals
        0 get-local -1 get-local fatan2 rad>deg
        [ dup 360 > ] [ 360 - ] while
        [ dup 0 < ] [ 360 + ] while load-local
        -3 get-local -2 get-local sq -1 get-local sq +
        sqrt 0 get-local 4 drop-locals
    ] [ alpha>> ] bi <LCHab> ;


USING: colors colors.lab colors.xyz ;

M: laba >rgba >xyza >rgba ;


USING: accessors colors.lab colors.xyz colors.xyz.private kernel
locals.backend math math.functions ;

M: laba >xyza
    [
        [ l>> ] [ a>> ] [ b>> ] tri 3 load-locals
        -2 get-local 16 + 116 / load-local -2 get-local 500 /
        0 get-local + load-local -1 get-local -2 get-local 200 /
        - load-local -1 get-local 3 ^ load-local
        -1 get-local 3 ^ load-local -1 get-local xyz_epsilon >
        -1 get-local
        [ load-local 0 get-local 1 drop-locals ] curry
        -3 get-local [
            load-local 116 0 get-local * 16 - xyz_kappa /
            1 drop-locals
        ] curry if load-local
        -8 get-local xyz_kappa xyz_epsilon * > -8 get-local
        [ load-local 0 get-local 16 + 116 / 3 ^ 1 drop-locals ]
        curry -8 get-local
        [ load-local 0 get-local xyz_kappa / 1 drop-locals ]
        curry if load-local -2 get-local xyz_epsilon >
        -2 get-local
        [ load-local 0 get-local 1 drop-locals ] curry
        -4 get-local [
            load-local 116 0 get-local * 16 - xyz_kappa /
            1 drop-locals
        ] curry if load-local -2 get-local wp_x *
        -1 get-local wp_y * 0 get-local wp_z * 11 drop-locals
    ] [ alpha>> ] bi <xyza> ;