image-js/src/roi/utils/colorMaps/getRainbowMap.ts

Image processing and manipulation in JavaScript

import { match } from 'ts-pattern';

import type { RoiKind } from '../../getRois.js';
import { hsvToRgb } from '../hsvToRgb.js';
import { rgbToNumber } from '../rgbToNumber.js';

export interface GetRainbowMapOptions {
  /**
   * Number of black ROIs.
   */
  nbNegative: number;
  /**
   * Number of white ID ROIs.
   */
  nbPositive: number;
  /**
   * Specify which ROIs to color.
   * @default `'bw'`
   */
  roiKind?: RoiKind;
}

/**
 * Return a map where ROIs are all different hues.
 * @param options - Get temperature map options.
 * @returns The colored map.
 */
export function getRainbowMap(options: GetRainbowMapOptions): Uint32Array {
  const { nbNegative, nbPositive, roiKind = 'bw' } = options;

  const colorMap = new Uint32Array(nbNegative + nbPositive + 1);

  const hueRange = 360;

  const step = match(roiKind)
    .with('bw', () => hueRange / (nbNegative + nbPositive))
    .with('black', () => hueRange / nbNegative)
    .with('white', () => hueRange / nbPositive)
    .exhaustive();

  // negative values
  let hue = 0;
  if (roiKind === 'bw' || roiKind === 'black') {
    for (let i = -nbNegative; i < 0; i++) {
      const hsv = [hue, 255, 255];
      colorMap[i + nbNegative] = rgbToNumber(hsvToRgb(hsv));
      hue += step;
    }
  }
  // positive values
  if (roiKind === 'bw' || roiKind === 'white') {
    for (let i = 1; i <= nbPositive; i++) {
      const hsv = [hue, 255, 255];
      colorMap[i + nbNegative] = rgbToNumber(hsvToRgb(hsv));
      hue += step;
    }
  }
  return colorMap;
}