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Do better chromatic adaptation for input RGB colors.

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This commit is contained in:
Nathan Vegdahl 2019-07-26 16:01:56 +09:00
parent f42eedfd08
commit f021def789
1 changed files with 13 additions and 35 deletions
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48
sub_crates/color/build.rs
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@ -20,10 +20,9 @@ fn main() {
w: (0.3127, 0.3290),
};
let to_xyz = rgb_to_xyz(chroma, 1.0);
let dest_path = Path::new(&out_dir).join("rec709_inc.rs");
let mut f = File::create(&dest_path).unwrap();
write_conversion_functions("rec709", to_xyz, &mut f);
write_conversion_functions("rec709", chroma, &mut f);
}
// Rec2020
@ -35,10 +34,9 @@ fn main() {
w: (0.3127, 0.3290),
};
let to_xyz = rgb_to_xyz(chroma, 1.0);
let dest_path = Path::new(&out_dir).join("rec2020_inc.rs");
let mut f = File::create(&dest_path).unwrap();
write_conversion_functions("rec2020", to_xyz, &mut f);
write_conversion_functions("rec2020", chroma, &mut f);
}
// ACES AP0
@ -50,10 +48,9 @@ fn main() {
w: (0.32168, 0.33767),
};
let to_xyz = rgb_to_xyz(chroma, 1.0);
let dest_path = Path::new(&out_dir).join("aces_ap0_inc.rs");
let mut f = File::create(&dest_path).unwrap();
write_conversion_functions("aces_ap0", to_xyz, &mut f);
write_conversion_functions("aces_ap0", chroma, &mut f);
}
// ACES AP1
@ -65,15 +62,16 @@ fn main() {
w: (0.32168, 0.33767),
};
let to_xyz = rgb_to_xyz(chroma, 1.0);
let dest_path = Path::new(&out_dir).join("aces_ap1_inc.rs");
let mut f = File::create(&dest_path).unwrap();
write_conversion_functions("aces_ap1", to_xyz, &mut f);
write_conversion_functions("aces_ap1", chroma, &mut f);
}
}
/// Generates conversion functions for the given rgb to xyz transform matrix.
fn write_conversion_functions(space_name: &str, to_xyz: [[f64; 3]; 3], f: &mut File) {
fn write_conversion_functions(space_name: &str, chroma: Chromaticities, f: &mut File) {
let to_xyz = rgb_to_xyz(chroma, 1.0);
f.write_all(
format!(
r#"
@ -129,7 +127,12 @@ pub fn xyz_to_{}(xyz: (f32, f32, f32)) -> (f32, f32, f32) {{
)
.unwrap();
let e_to_xyz = adapt_to_e(to_xyz, 1.0);
let e_chroma = {
let mut e_chroma = chroma;
e_chroma.w = (1.0 / 3.0, 1.0 / 3.0);
e_chroma
};
let e_to_xyz = rgb_to_xyz(e_chroma, 1.0);
f.write_all(
format!(
r#"
@ -237,31 +240,6 @@ fn rgb_to_xyz(chroma: Chromaticities, y: f64) -> [[f64; 3]; 3] {
mat
}
/// Chromatically adapts a matrix from `rgb_to_xyz` to a whitepoint of E.
///
/// In other words, makes it so that RGB (1,1,1) maps to XYZ (1,1,1).
fn adapt_to_e(mat: [[f64; 3]; 3], y: f64) -> [[f64; 3]; 3] {
let r_fac = y / (mat[0][0] + mat[0][1] + mat[0][2]);
let g_fac = y / (mat[1][0] + mat[1][1] + mat[1][2]);
let b_fac = y / (mat[2][0] + mat[2][1] + mat[2][2]);
let mut mat2 = [[0.0; 3]; 3];
mat2[0][0] = mat[0][0] * r_fac;
mat2[0][1] = mat[0][1] * r_fac;
mat2[0][2] = mat[0][2] * r_fac;
mat2[1][0] = mat[1][0] * g_fac;
mat2[1][1] = mat[1][1] * g_fac;
mat2[1][2] = mat[1][2] * g_fac;
mat2[2][0] = mat[2][0] * b_fac;
mat2[2][1] = mat[2][1] * b_fac;
mat2[2][2] = mat[2][2] * b_fac;
mat2
}
/// Calculates the inverse of the given 3x3 matrix.
///
/// Ported to Rust from `gjInverse()` in IlmBase's Imath/ImathMatrix.h