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XYZ color curve functions need more accurate exp function.

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This commit is contained in:
Nathan Vegdahl 2017-06-15 22:50:27 -07:00
parent b5f2237676
commit 2c0e57341c
1 changed files with 5 additions and 5 deletions
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10
src/color.rs
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@ -4,7 +4,7 @@ use spectra_xyz::{spectrum_xyz_to_p, EQUAL_ENERGY_REFLECTANCE};
use float4::Float4; use float4::Float4;
use lerp::Lerp; use lerp::Lerp;
use math::faster_exp; use math::fast_exp;
pub use color_util::{xyz_to_rec709, xyz_to_rec709_e, rec709_to_xyz, rec709_e_to_xyz}; pub use color_util::{xyz_to_rec709, xyz_to_rec709_e, rec709_to_xyz, rec709_e_to_xyz};
@ -278,18 +278,18 @@ pub fn x_1931(wavelength: f32) -> f32 {
let t1 = (wavelength - 442.0) * (if wavelength < 442.0 { 0.0624 } else { 0.0374 }); let t1 = (wavelength - 442.0) * (if wavelength < 442.0 { 0.0624 } else { 0.0374 });
let t2 = (wavelength - 599.8) * (if wavelength < 599.8 { 0.0264 } else { 0.0323 }); let t2 = (wavelength - 599.8) * (if wavelength < 599.8 { 0.0264 } else { 0.0323 });
let t3 = (wavelength - 501.1) * (if wavelength < 501.1 { 0.0490 } else { 0.0382 }); let t3 = (wavelength - 501.1) * (if wavelength < 501.1 { 0.0490 } else { 0.0382 });
(0.362 * faster_exp(-0.5 * t1 * t1)) + (1.056 * faster_exp(-0.5 * t2 * t2)) - (0.362 * fast_exp(-0.5 * t1 * t1)) + (1.056 * fast_exp(-0.5 * t2 * t2)) -
(0.065 * faster_exp(-0.5 * t3 * t3)) (0.065 * fast_exp(-0.5 * t3 * t3))
} }
pub fn y_1931(wavelength: f32) -> f32 { pub fn y_1931(wavelength: f32) -> f32 {
let t1 = (wavelength - 568.8) * (if wavelength < 568.8 { 0.0213 } else { 0.0247 }); let t1 = (wavelength - 568.8) * (if wavelength < 568.8 { 0.0213 } else { 0.0247 });
let t2 = (wavelength - 530.9) * (if wavelength < 530.9 { 0.0613 } else { 0.0322 }); let t2 = (wavelength - 530.9) * (if wavelength < 530.9 { 0.0613 } else { 0.0322 });
(0.821 * faster_exp(-0.5 * t1 * t1)) + (0.286 * faster_exp(-0.5 * t2 * t2)) (0.821 * fast_exp(-0.5 * t1 * t1)) + (0.286 * fast_exp(-0.5 * t2 * t2))
} }
pub fn z_1931(wavelength: f32) -> f32 { pub fn z_1931(wavelength: f32) -> f32 {
let t1 = (wavelength - 437.0) * (if wavelength < 437.0 { 0.0845 } else { 0.0278 }); let t1 = (wavelength - 437.0) * (if wavelength < 437.0 { 0.0845 } else { 0.0278 });
let t2 = (wavelength - 459.0) * (if wavelength < 459.0 { 0.0385 } else { 0.0725 }); let t2 = (wavelength - 459.0) * (if wavelength < 459.0 { 0.0385 } else { 0.0725 });
(1.217 * faster_exp(-0.5 * t1 * t1)) + (0.681 * faster_exp(-0.5 * t2 * t2)) (1.217 * fast_exp(-0.5 * t1 * t1)) + (0.681 * fast_exp(-0.5 * t2 * t2))
} }