convolute function

void convolute(Uint8List pixels, int width, int height, List<num> weights, num bias)

Implementation

void convolute(
    Uint8List pixels, int width, int height, List<num> weights, num bias) {
  var bytes = Uint8List.fromList(pixels);
  int side = sqrt(weights.length).round();
  int halfSide = ~~(side / 2).round() - side % 2;
  int sw = width;
  int sh = height;

  int w = sw;
  int h = sh;

  for (int y = 0; y < h; y++) {
    for (int x = 0; x < w; x++) {
      int sy = y;
      int sx = x;
      int dstOff = (y * w + x) * 4;
      num r = bias, g = bias, b = bias;
      for (int cy = 0; cy < side; cy++) {
        for (int cx = 0; cx < side; cx++) {
          int scy = sy + cy - halfSide;
          int scx = sx + cx - halfSide;

          if (scy >= 0 && scy < sh && scx >= 0 && scx < sw) {
            int srcOff = (scy * sw + scx) * 4;
            num wt = weights[cy * side + cx];

            r += bytes[srcOff] * wt;
            g += bytes[srcOff + 1] * wt;
            b += bytes[srcOff + 2] * wt;
          }
        }
      }
      pixels[dstOff] = clampPixel(r.round());
      pixels[dstOff + 1] = clampPixel(g.round());
      pixels[dstOff + 2] = clampPixel(b.round());
    }
  }
}