expo-image/src/utils/blurhash/utils.ts

A cross-platform, performant image component for React Native and Expo with Web support

export const sRGBToLinear = (value: number) => {
  const v = value / 255;
  if (v <= 0.04045) {
    return v / 12.92;
  } else {
    return Math.pow((v + 0.055) / 1.055, 2.4);
  }
};

export const linearTosRGB = (value: number) => {
  const v = Math.max(0, Math.min(1, value));
  if (v <= 0.0031308) {
    return Math.trunc(v * 12.92 * 255 + 0.5);
  } else {
    return Math.trunc((1.055 * Math.pow(v, 1 / 2.4) - 0.055) * 255 + 0.5);
  }
};

export const sign = (n: number) => (n < 0 ? -1 : 1);

export const signPow = (val: number, exp: number) => sign(val) * Math.pow(Math.abs(val), exp);