fast add of two 24/32 bit color
lsb of RG component must be set too zero
public int addRGBColor(int color1,int color2)
{
color1 &=0xFEFEFE; //set some lsb to 0
color2 &=0xFEFEFE; //set some lsb to 0
int color=color1+color2; //add color
color|=(( color>>8 ) &0x010101)*0xFF; //clamp color to 0 - 255
}
this introduce a little error on lsb bits but it is very fast