Skin Color Detection

Skin Color Detection with HSV Lookup

Skin color detection algorithms are used to detect human body. A primitive algorithm to this is the HSV lookup. At first a pixel is converted to its HSV values and according to definition (1) either a pixel is skin component or not. If pixel is not a skin component then it is painted white. H is for Hue value and S is for Saturation value.

(1)

(a) (b)

(e) (f)

(g) (h)

Figure 1. (a), (c), (e) and (g) are original images and (b), (d), (f) and (h) are skin detected images

C Source Code

Below there is only skin color detection procedure. You can reach complete source code from here.

int Find_Skin(long **RRed, long **GGreen, long **BBlue, long width, long height)
{
   long i, j, Value, R, G, B, tmp;
   double Saturation, Hue, Cr, Cg, Cb;

   for(i=0;i<height;i++)
   {
      for(j=0;j<width;j++)
      {
        R = RRed[i][j];
        G = GGreen[i][j];
        B = BBlue[i][j];
        ///////////////////  VALUE
        // find maximum
        if ( (R >= G) && (R >= B))
           Value = R;
        else if ( (G >= R) && (G >= B))
           Value = G;
        else if ( (B >= G) && (B >= R))
           Value = B;
        ///////////////////  SATURATION
        // find minimum
        if ( (R <= G) && (R <= B))
           tmp = R;
        else if ( (G <= R) && (G <= B))
           tmp = G;
        else if ( (B <= G) && (B <= R))
           tmp = B;
        if (Value == 0)
           Saturation = 0;
        else
           Saturation = ((double)Value - (double)tmp)/(double)Value;
        ///////////////////  SATURATION
        if (Saturation == 0)
           Hue = -1;
        else
        {
           Cr = ((double)Value-(double)R)/((double)Value-(double)tmp);
           Cg = ((double)Value-(double)G)/((double)Value-(double)tmp);
           Cb = ((double)Value-(double)B)/((double)Value-(double)tmp);
           if (R == Value)
              Hue = Cb - Cg;
           if (G == Value)
              Hue = 2 + Cr - Cb;
           if (B == Value)
              Hue = 4 + Cg - Cr;
           Hue *= 60;
           if (Hue < 0)
                                    Hue +=360;
        }
        ///////////////////////
        // DETECT SKIN COLOR //
        ///////////////////////
        if ( (Hue >= 0.0) && (Hue <= 50.0) && (Saturation >= 0.23) && (Saturation <= 0.68) )
        {
           RRed[i][j] = R;
           GGreen[i][j] = G;
           BBlue[i][j] = B;
        }
        else
        {
          RRed[i][j] = 255;
          GGreen[i][j] = 255;
          BBlue[i][j] = 255;
        }
      }
   }

   return 0;
}