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colorspace: Remove unused module.

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It’s unused since commit 7e473003a6
(#23782).

Signed-off-by: Anders Kaseorg <anders@zulip.com>
This commit is contained in:
Anders Kaseorg 2023-08-31 11:24:57 -07:00 committed by Tim Abbott
parent ebfe9637c8
commit 38e7a85e90
2 changed files with 0 additions and 71 deletions
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32
web/src/colorspace.ts
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@ -1,32 +0,0 @@
// Convert an sRGB value in [0, 255] to a linear intensity
// value in [0, 1].
//
// https://en.wikipedia.org/wiki/SRGB#The_reverse_transformation
export function sRGB_to_linear(v: number): number {
v = v / 255;
if (v <= 0.04045) {
return v / 12.92;
}
return Math.pow((v + 0.055) / 1.055, 2.4);
}
// Compute luminance (CIE Y stimulus) from linear intensity
// of sRGB / Rec. 709 primaries.
export function rgb_luminance(channel: [number, number, number]): number {
return 0.2126 * channel[0] + 0.7152 * channel[1] + 0.0722 * channel[2];
}
// Convert luminance (photometric, CIE Y)
// to lightness (perceptual, CIE L*)
//
// https://en.wikipedia.org/wiki/Lab_color_space#Forward_transformation
export function luminance_to_lightness(luminance: number): number {
let v;
if (luminance <= 216 / 24389) {
v = (841 / 108) * luminance + 4 / 29;
} else {
v = Math.pow(luminance, 1 / 3);
}
return 116 * v - 16;
}

39
web/tests/colorspace.test.js
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@ -1,39 +0,0 @@
"use strict";
const {strict: assert} = require("assert");
const {zrequire} = require("./lib/namespace");
const {run_test} = require("./lib/test");
const colorspace = zrequire("colorspace");
run_test("sRGB_to_linear", () => {
let srgb_color = 0.0042;
let expected_value = 0.0042 / 255 / 12.92;
let actual_value = colorspace.sRGB_to_linear(srgb_color);
assert.equal(actual_value, expected_value);
srgb_color = 255;
expected_value = 1;
actual_value = colorspace.sRGB_to_linear(srgb_color);
assert.equal(actual_value, expected_value);
});
run_test("rgb_luminance", () => {
const channel = [1, 1, 1];
const expected_value = 1;
const actual_value = colorspace.rgb_luminance(channel);
assert.equal(actual_value, expected_value);
});
run_test("luminance_to_lightness", () => {
let luminance = 0;
let expected_value = (116 * 4) / 29 - 16;
let actual_value = colorspace.luminance_to_lightness(luminance);
assert.equal(actual_value, expected_value);
luminance = 1;
expected_value = 100;
actual_value = colorspace.luminance_to_lightness(luminance);
assert.equal(actual_value, expected_value);
});