uniform shader image;
uniform float2 imageSize;
uniform float2 pixelCount;
half4 main(float2 coord) {
  float2 tc = coord / imageSize;
  tc.x = (floor(tc.x * pixelCount.x) + 0.5) / pixelCount.x;
  tc.y = (floor(tc.y * pixelCount.y) + 0.5) / pixelCount.y;
  tc *= imageSize;
  return image.eval(tc);
}