Document the proper gamma functions for
	ITU_R_BT_601_625_LINE
		GAMMA = 1 / 0.45 = 2.(2)
		OFFSET = 0.09929682680944
		SLOPE = 4.5
		TRANSITION = 0.018053968510807
	ITU_R_BT_601_525_LINE (same function as above)
	ITU_R_BT_709 (same function as above)
	ITU_R_BT_2020 (same function as above)
	NTSC_RGB (same function as above)
	PAL_SECAM_RGB (same function as above)
	SMPTE_C_RGB (same function as above)
	SMPTE_240M_RGB
		GAMMA = 1 / 0.45 = 2.(2)
		OFFSET = 0.1115721957735072
		SLOPE = 4.0
		TRANSITION = 0.022821585552393633
	SGI_RGB
		simple: gamma = 1.47