Function RGBToGreyscale

src/heightmap.cpp:69–74

* Convert RGB colours to Greyscale using 29.9% Red, 58.7% Green, 11.4% Blue * (average luminosity formula, NTSC Colour Space) */

 *  (average luminosity formula, NTSC Colour Space)
 */
static inline uint8_t RGBToGreyscale(uint8_t red, uint8_t green, uint8_t blue)
{
	/* To avoid doubles and stuff, multiply it with a total of 65536 (16bits), then
	 *  divide by it to normalize the value to a byte again. */
	return ((red * 19595) + (green * 38470) + (blue * 7471)) / 65536;
}


#ifdef WITH_PNG