mlib_ImageColorRGB2HSL(3MLIB)				    mediaLib Library Functions				     mlib_ImageColorRGB2HSL(3MLIB)

NAME

       mlib_ImageColorRGB2HSL - RGB to HSL color conversion

SYNOPSIS

       cc [ flag... ] file... -lmlib [ library... ]
       #include <mlib.h>

       mlib_status mlib_ImageColorRGB2HSL(mlib_image *dst, const mlib_image *src);

DESCRIPTION

       The  mlib_ImageColorRGB2HSL()  function	performs  a conversion from red/green/blue to hue/saturation/lightness. The source and destination
       images must be three-channel images.

       It uses the following equations:

	  V = max(R, G, B)
       Vmin = min(R, G, B)

	  L = (V + Vmin)/2

	  S = (V - Vmin)/(V + Vmin)	    if L <= 1/2
	  S = (V - Vmin)/(2 - V - Vmin)     if L > 1/2

	  H = (5.0 + (V - B)/(V - Vmin))/6  if R = V and G = Vmin
	  H = (1.0 - (V - G)/(V - Vmin))/6  if R = V and B = Vmin
	  H = (1.0 + (V - R)/(V - Vmin))/6  if G = V and B = Vmin
	  H = (3.0 - (V - B)/(V - Vmin))/6  if G = V and R = Vmin
	  H = (3.0 + (V - G)/(V - Vmin))/6  if B = V and R = Vmin
	  H = (5.0 - (V - R)/(V - Vmin))/6  if B = V and G = Vmin
	  H = 0.0			    if R = G = B

       where 0 <= R, G, B, V, Vmin, L, S <= 1 and 0 <= H < 1.

       Assuming a pixel in the source image is (r, g, b) and its corresponding pixel in the destination image is (h, s,  l),  then  for  MLIB_BYTE
       images, the following applies:

	  R = r/255
	  G = g/255
	  B = b/255
	  h = H*256
	  s = S*255
	  l = L*255

       for MLIB_SHORT images, the following applies:

	  R = (r + 32768)/65535
	  G = (g + 32768)/65535
	  B = (b + 32768)/65535
	  h = H*65536 - 32768
	  s = S*65535 - 32768
	  l = L*65535 - 32768

       for MLIB_USHORT images, the following applies:

	  R = r/65535
	  G = g/65535
	  B = b/65535
	  h = H*65536
	  s = S*65535
	  l = L*65535

       and for MLIB_INT images, the following applies:

	  R = (r + 2147483648)/4294967295
	  G = (g + 2147483648)/4294967295
	  B = (b + 2147483648)/4294967295
	  h = H*4294967296 - 2147483648
	  s = S*4294967295 - 2147483648
	  l = L*4294967295 - 2147483648

PARAMETERS

       The function takes the following arguments:

       dst	       Pointer to destination image.

       src	       Pointer to source image.

RETURN VALUES

       The function returns MLIB_SUCCESS if successful. Otherwise it returns MLIB_FAILURE.

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Interface Stability	     |Evolving			   |
       +-----------------------------+-----------------------------+
       |MT-Level		     |MT-Safe			   |
       +-----------------------------+-----------------------------+

SEE ALSO

       mlib_ImageColorHSL2RGB(3MLIB), mlib_ImageColorHSL2RGB_Fp(3MLIB), mlib_ImageColorRGB2HSL_Fp(3MLIB), attributes(5)

SunOS 5.10							    10 Nov 2004 				     mlib_ImageColorRGB2HSL(3MLIB)