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Add OkLrab and OkLrCh #511

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Aug 26, 2024
Merged

Add OkLrab and OkLrCh #511

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b34f781
Add OkLrab and OkLrCh
facelessuser May 2, 2024
61d0f70
Rebase accounting for null changes
facelessuser Jun 1, 2024
3da03e1
Refactor to account for recent changes
facelessuser Aug 26, 2024
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2 changes: 2 additions & 0 deletions src/space-coord-accessors.d.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -27,6 +27,8 @@ declare class SpaceAccessors {
okhsv: SpaceAccessor;
oklab: SpaceAccessor;
oklch: SpaceAccessor;
oklrab: SpaceAccessor;
oklrch: SpaceAccessor;
p3: SpaceAccessor;
p3_linear: SpaceAccessor;
prophoto: SpaceAccessor;
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2 changes: 2 additions & 0 deletions src/spaces/index-fn.js
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Expand Up @@ -23,6 +23,8 @@ export {default as REC_2020_Linear} from "./rec2020-linear.js";
export {default as REC_2020} from "./rec2020.js";
export {default as OKLab} from "./oklab.js";
export {default as OKLCH} from "./oklch.js";
export {default as OKLrab} from "./oklrab.js";
export {default as OKLrCH} from "./oklrch.js";
export {default as Okhsl} from "./okhsl.js";
export {default as Okhsv} from "./okhsv.js";
export {default as CAM16_JMh} from "./cam16.js";
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37 changes: 37 additions & 0 deletions src/spaces/oklrab.js
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@@ -0,0 +1,37 @@
import ColorSpace from "../ColorSpace.js";
import OKLab from "./oklab.js";
import {toe, toeInv} from "./okhsl.js";

export default new ColorSpace({
id: "oklrab",
name: "Oklrab",
coords: {
l: {
refRange: [0, 1],
name: "Lightness",
},
a: {
refRange: [-0.4, 0.4],
},
b: {
refRange: [-0.4, 0.4],
},
},

// Note that XYZ is relative to D65
white: "D65",

base: OKLab,
fromBase (oklab) {
return [toe(oklab[0]), oklab[1], oklab[2]];
},
toBase (oklrab) {
return [toeInv(oklrab[0]), oklrab[1], oklrab[2]];
},

formats: {
"color": {
coords: ["<percentage> | <number>", "<number> | <percentage>[-1,1]", "<number> | <percentage>[-1,1]"],
},
},
});
34 changes: 34 additions & 0 deletions src/spaces/oklrch.js
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@@ -0,0 +1,34 @@
import ColorSpace from "../ColorSpace.js";
import OKLrab from "./oklrab.js";
import lch from "./lch.js";

export default new ColorSpace({
id: "oklrch",
name: "Oklrch",
coords: {
l: {
refRange: [0, 1],
name: "Lightness",
},
c: {
refRange: [0, 0.4],
name: "Chroma",
},
h: {
refRange: [0, 360],
type: "angle",
name: "Hue",
},
},
white: "D65",

base: OKLrab,
fromBase: lch.fromBase,
toBase: lch.toBase,

formats: {
"color": {
coords: ["<percentage> | <number>", "<number> | <percentage>[0,1]", "<number> | <angle>"],
},
},
});
62 changes: 59 additions & 3 deletions test/conversions.js
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Expand Up @@ -430,22 +430,78 @@ const tests = {
expect: [1.0, 0.0, null],
},
{
name: "sRGB red (D65) to OKlab",
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good catch, yes

name: "sRGB red (D65) to OKlch",
args: "red",
expect: [0.6279553639214311, 0.2576833038053608, 29.23388027962784],
},
{
name: "sRGB lime (D65) to OKlab",
name: "sRGB lime (D65) to OKlch",
args: "lime",
expect: [0.8664396175234368, 0.2948272245426958, 142.4953450414439],
},
{
name: "sRGB blue (D65) to OKlab",
name: "sRGB blue (D65) to OKlch",
args: "blue",
expect: [0.45201371817442365, 0.3132143886344849, 264.0520226163699],
},
],
},
{
name: "OKLrab",
data: {
toSpace: "oklrab",
},
tests: [
{
name: "sRGB white (D65) to OKlrab",
args: "white",
expect: [ 1.0000000000000002, -4.996003610813204e-16, 0 ],
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Should this actually be zero and this is cumulative error?

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Yeah, cumulative floating point error.

Oklab in Color.js currently yields that for white, so OkLrab will also yield that for white as OkLrab just applies a toe function to the lightness, and at white, there is no change.

> new Color('white').to('oklab').coords
[ 1.0000000000000002, -4.996003610813204e-16, 0 ]

Floating point errors can vary slightly depending on how the original matrix was generated, the exact steps and in what order. The invert matrix result can be slightly different (floating point error-wise) depending on exactly how the inversion is performed (did it use LU decomposition, some other way, what order were operations done in, etc).

This isn't too different for other Lab-like spaces, especially those that employ more complicated calculations:

> new Color('white').to('ictcp').coords
[ 0.5806888810416109, 1.1102230246251565e-16, 2.914335439641036e-16 ]

I think my library has slightly different floating point errors. It yields an exact 1 for lightness, but non-zero results for both a and b.

>>> Color('white').convert('oklab').coords()
[1.0, -4.996003610813204e-16, 1.1102230246251565e-16]

But the same things happen for various other Lab-ish spaces (Y is the lightness in XYB):

>>> Color('white').convert('hunter-lab').coords()
[100.0, 1.912989643463523e-14, -7.46260389005987e-15]
>>> Color('white').convert('xyb').coords()
[0.0, 0.8453085619621621, 2.220446049250313e-16]

},
{
name: "sRGB red (D65) to OKlrab",
args: "red",
expect: [ 0.5680846563197034, 0.2248630684262744, 0.125846277330585 ],
},
{
name: "sRGB lime (D65) to OKlrab",
args: "lime",
expect: [ 0.8445289714936317, -0.23388758093655815, 0.1794984451609376 ],
},
{
name: "sRGB blue (D65) to OKlrab",
args: "blue",
expect: [ 0.3665653391870817, -0.03245697517079771, -0.3115281656775778 ],
},
],
},
{
name: "OKLrCh",
data: {
toSpace: "oklrch",
},
tests: [
{
name: "sRGB white (D65) to OKlrch",
args: "white",
expect: [1.0, 0.0, null],
},
{
name: "sRGB red (D65) to OKlrch",
args: "red",
expect: [0.5680846563197034, 0.2576833038053608, 29.23388027962784],
},
{
name: "sRGB lime (D65) to OKlrch",
args: "lime",
expect: [0.8445289714936317, 0.2948272245426958, 142.4953450414439],
},
{
name: "sRGB blue (D65) to OKlrch",
args: "blue",
expect: [0.3665653391870817, 0.3132143886344849, 264.0520226163699],
},
],
},
{
name: "Linear-light sRGB",
data: {
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4 changes: 4 additions & 0 deletions types/src/spaces/oklrab.d.ts
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@@ -0,0 +1,4 @@
declare const _default: ColorSpace;
export default _default;
import ColorSpace from "../ColorSpace.js";
//# sourceMappingURL=oklrab.d.ts.map
4 changes: 4 additions & 0 deletions types/src/spaces/oklrch.d.ts
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@@ -0,0 +1,4 @@
declare const _default: ColorSpace;
export default _default;
import ColorSpace from "../ColorSpace.js";
//# sourceMappingURL=oklrch.d.ts.map
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