pokus.cl

#define E .0000001f

bool fEqual(float x, float y)
{
    return (x+E > y && x-E < y);
}

float4 rgba2hsla(float4 rgba) {
  float M = max(rgba.x, rgba.y);
  M = max(M, rgba.z);
  float m = min(rgba.x, rgba.y);
  m = min(m, rgba.z);
  float chroma = M-m; //calculate chroma
  float lightness = (M+m)/2.0f;
  float saturation = chroma/(1.0f-fabs(2.0f*lightness-1.0f));

  float hue = 0;
  if (fEqual(rgba.x, M))
      hue = fmod((rgba.y - rgba.z)/chroma, 6.0f);
  if (fEqual(rgba.y, M))
      hue = (((rgba.z - rgba.x))/chroma) + 2;
  if (fEqual(rgba.z, M))
      hue = (((rgba.x - rgba.y))/chroma) + 4;
  hue *= 60.0f;
  return (float4)(hue, saturation, lightness, rgba.w);
}
float hue2rgb(float p, float q, float t) {
  if(t < 0.0f) t += 1;
  if(t > 1.0f) t -= 1;
  if(t < (float)(1/6)) return p + (q - p) * 6.0f * t;
  if(t < (float)(1/2)) return q;
  if(t < (float)(2/3)) return p + (q - p) * (2/3 - t) * 6.0f;
  return p;
}
// Convert <0,1> ranged rgba floats to <0,255> uchars
uchar4 floatrgba2ucharrgba(float4 in) {
  return (uchar4)(convert_uchar_rte(in.x*255.0f),
                  convert_uchar_rte(in.y*255.0f),
                  convert_uchar_rte(in.z*255.0f),
                  convert_uchar_rte(in.w*255.0f));
  // return (uchar4)((in.x*255.0f),
  //                 (in.y*255.0f),
  //                 (in.z*255.0f),
  //                 (in.w*255.0f));
}

float4 hsl2rgb_stackoverflow(float4 gMem)
{
    float4 rgb = (float4)(0,0,0,gMem.w);
    if(fEqual(gMem.y,0.0f)){
        rgb.x = rgb.y = rgb.z = gMem.z; // achromatic
    }
    else {
      //calculate chroma
      float chroma = (1.0f - fabs( (float)(2.0f*gMem.z - 1.0f) )) * gMem.y;
      float H = gMem.x/60.0f;
      float x = chroma * (1.0f - fabs( fmod(H, 2.0f) - 1.0f ));

      switch((int)H)
      {
          case 0:
              rgb = (float4)(chroma, x, 0,gMem.w);
              break;
          case 1:
              rgb = (float4)(x, chroma, 0,gMem.w);
              break;
          case 2:
              rgb = (float4)(0, chroma, x,gMem.w);
              break;
          case 3:
              rgb = (float4)(0, x, chroma,gMem.w);
              break;
          case 4:
              rgb = (float4)(x, 0, chroma,gMem.w);
              break;
          case 5:
              rgb = (float4)(chroma, 0, x,gMem.w);
              break;
          default:
              rgb = (float4)(0, 0, 0,gMem.w);
      }

      rgb += gMem.z - .5f*chroma;

      return rgb;
    }
}

__kernel void saturate(
   __global const uchar* src_ptr,
   __global uchar* out_ptr)
{
  const int it = get_global_id(0);
  const uchar b = src_ptr[3*it + 0];
  const uchar g = src_ptr[3*it + 1];
  const uchar r = src_ptr[3*it + 2];
  float4 rgba = (float4)(r,g,b,1.0f);
  rgba /= 255.0f;
  float4 hsla = rgba2hsla(rgba);
  //hsla.y = sqrt(hsla.y);
  //float4 rgbaNew = hsla2rgba(hsla);
  float4 rgbaNew = hsl2rgb_stackoverflow(hsla);
  uchar4 rgbaNewInt = floatrgba2ucharrgba(rgbaNew);
  //rgbaNewInt = (uchar4)(hsla.y*255, hsla.y*255, hsla.y*255, hsla.w*255);
  out_ptr[3*it + 0] = rgbaNewInt.z;
  out_ptr[3*it + 1] = rgbaNewInt.y;
  out_ptr[3*it + 2] = rgbaNewInt.x;
}