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/**
* @preserve
* Copyright 2015-2018 Igor Bezkrovnyi
* All rights reserved. (MIT Licensed)
*
* manhattanNeuQuant.ts - part of Image Quantization Library
*/
import { AbstractDistanceCalculator } from './distanceCalculator';
import { Y } from '../constants/bt709';
/**
* Manhattan distance (NeuQuant modification) - w/o sRGB coefficients
*/
export abstract class AbstractManhattan extends AbstractDistanceCalculator {
declare protected _kR: number;
declare protected _kG: number;
declare protected _kB: number;
declare protected _kA: number;
calculateRaw(
r1: number,
g1: number,
b1: number,
a1: number,
r2: number,
g2: number,
b2: number,
a2: number,
) {
let dR = r2 - r1;
let dG = g2 - g1;
let dB = b2 - b1;
let dA = a2 - a1;
if (dR < 0) dR = 0 - dR;
if (dG < 0) dG = 0 - dG;
if (dB < 0) dB = 0 - dB;
if (dA < 0) dA = 0 - dA;
return this._kR * dR + this._kG * dG + this._kB * dB + this._kA * dA;
}
}
export class Manhattan extends AbstractManhattan {
protected _setDefaults() {
this._kR = 1;
this._kG = 1;
this._kB = 1;
this._kA = 1;
}
}
/**
* Manhattan distance (Nommyde modification)
* https://github.com/igor-bezkrovny/image-quantization/issues/4#issuecomment-235155320
*/
export class ManhattanNommyde extends AbstractManhattan {
protected _setDefaults() {
this._kR = 0.4984;
this._kG = 0.8625;
this._kB = 0.2979;
// TODO: what is the best coefficient below?
this._kA = 1;
}
}
/**
* Manhattan distance (sRGB coefficients)
*/
export class ManhattanBT709 extends AbstractManhattan {
protected _setDefaults() {
this._kR = Y.RED;
this._kG = Y.GREEN;
this._kB = Y.BLUE;
// TODO: what is the best coefficient below?
this._kA = 1;
}
}