'\" te
.\" Copyright (c) 2007, Sun Microsystems, Inc.  All Rights Reserved 
.TH mlib_ImageColorRGB2HSL 3MLIB "2 Mar 2007" "SunOS 5.11" "mediaLib Library Functions"
.SH NAME
mlib_ImageColorRGB2HSL \- RGB to HSL color conversion
.SH SYNOPSIS
.LP
.nf
cc [ \fIflag\fR... ] \fIfile\fR... \fB-lmlib\fR [ \fIlibrary\fR... ]
#include <mlib.h>

\fBmlib_status\fR \fBmlib_ImageColorRGB2HSL\fR(\fBmlib_image *\fR\fIdst\fR, \fBconst mlib_image *\fR\fIsrc\fR);
.fi

.SH DESCRIPTION
.sp
.LP
The \fBmlib_ImageColorRGB2HSL()\fR function performs a conversion from red/green/blue to hue/saturation/lightness. The source and destination images must be three-channel images.
.sp
.LP
It uses the following equations:
.sp
.in +2
.nf
   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
.fi
.in -2

.sp
.LP
where \fB0 \(<= R, G, B, V, Vmin, L, S \(<= 1\fR and \fB0 \(<= H < 1\fR.
.sp
.LP
Assuming a pixel in the source image is \fB(r, g, b)\fR and its corresponding pixel in the destination image is \fB(h, s, l)\fR, then for \fBMLIB_BYTE\fR images, the following applies:
.sp
.in +2
.nf
   R = r/255
   G = g/255
   B = b/255
   h = H*256
   s = S*255
   l = L*255
.fi
.in -2

.sp
.LP
for \fBMLIB_SHORT\fR images, the following applies:
.sp
.in +2
.nf
   R = (r + 32768)/65535
   G = (g + 32768)/65535
   B = (b + 32768)/65535
   h = H*65536 - 32768
   s = S*65535 - 32768
   l = L*65535 - 32768
.fi
.in -2

.sp
.LP
for \fBMLIB_USHORT\fR images, the following applies:
.sp
.in +2
.nf
   R = r/65535
   G = g/65535
   B = b/65535
   h = H*65536
   s = S*65535
   l = L*65535
.fi
.in -2

.sp
.LP
and for \fBMLIB_INT\fR images, the following applies:
.sp
.in +2
.nf
   R = (r + 2147483648)/4294967295
   G = (g + 2147483648)/4294967295
   B = (b + 2147483648)/4294967295
   h = H*4294967296 - 2147483648
   s = S*4294967295 - 2147483648
   l = L*4294967295 - 2147483648
.fi
.in -2

.SH PARAMETERS
.sp
.LP
The function takes the following arguments:
.sp
.ne 2
.mk
.na
\fB\fIdst\fR\fR
.ad
.RS 7n
.rt  
Pointer to destination image.
.RE

.sp
.ne 2
.mk
.na
\fB\fIsrc\fR\fR
.ad
.RS 7n
.rt  
Pointer to source image.
.RE

.SH RETURN VALUES
.sp
.LP
The function returns \fBMLIB_SUCCESS\fR if successful. Otherwise it returns \fBMLIB_FAILURE\fR.
.SH ATTRIBUTES
.sp
.LP
See \fBattributes\fR(5) for descriptions of the following attributes:
.sp

.sp
.TS
tab() box;
cw(2.75i) |cw(2.75i) 
lw(2.75i) |lw(2.75i) 
.
ATTRIBUTE TYPEATTRIBUTE VALUE
_
Interface StabilityCommitted
_
MT-LevelMT-Safe
.TE

.SH SEE ALSO
.sp
.LP
\fBmlib_ImageColorHSL2RGB\fR(3MLIB), \fBmlib_ImageColorHSL2RGB_Fp\fR(3MLIB), \fBmlib_ImageColorRGB2HSL_Fp\fR(3MLIB), \fBattributes\fR(5)