Function applyDCT

plugins/plugin-hash/src/phash.ts:163–187

(f: number[][], size: number)

}

function applyDCT(f: number[][], size: number) {
  const N = size;
  const F: number[][] = [];

  for (let u = 0; u < N; u++) {
    const row = [];
    for (let v = 0; v < N; v++) {
      let sum = 0;
      for (let i = 0; i < N; i++) {
        for (let j = 0; j < N; j++) {
          sum +=
            Math.cos(((2 * i + 1) / (2.0 * N)) * u * Math.PI) *
            Math.cos(((2 * j + 1) / (2.0 * N)) * v * Math.PI) *
            f[i]![j]!;
        }
      }

      sum *= (c[u]! * c[v]!) / 4;
      row[v] = sum;
      F[u] = row;
    }
  }

  return F;
}

export default ImagePHash;