4.4BSD/usr/src/contrib/X11R5-lib/lib/X/CIELuv.c
/* $XConsortium: CIELuv.c,v 1.10 92/03/03 14:15:02 rws Exp $" */
/*
* Code and supporting documentation (c) Copyright 1990 1991 Tektronix, Inc.
* All Rights Reserved
*
* This file is a component of an X Window System-specific implementation
* of XCMS based on the TekColor Color Management System. Permission is
* hereby granted to use, copy, modify, sell, and otherwise distribute this
* software and its documentation for any purpose and without fee, provided
* that this copyright, permission, and disclaimer notice is reproduced in
* all copies of this software and in supporting documentation. TekColor
* is a trademark of Tektronix, Inc.
*
* Tektronix makes no representation about the suitability of this software
* for any purpose. It is provided "as is" and with all faults.
*
* TEKTRONIX DISCLAIMS ALL WARRANTIES APPLICABLE TO THIS SOFTWARE,
* INCLUDING THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
* PARTICULAR PURPOSE. IN NO EVENT SHALL TEKTRONIX BE LIABLE FOR ANY
* SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER
* RESULTING FROM LOSS OF USE, DATA, OR PROFITS, WHETHER IN AN ACTION OF
* CONTRACT, NEGLIGENCE, OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
* CONNECTION WITH THE USE OR THE PERFORMANCE OF THIS SOFTWARE.
*
*
* NAME
* CIELuv.c
*
* DESCRIPTION
* This file contains routines that support the CIE L*u*v*
* color space to include conversions to and from the CIE
* XYZ space.
*
* DOCUMENTATION
* "TekColor Color Management System, System Implementor's Manual"
* and
* Fred W. Billmeyer & Max Saltzman, "Principles of Color
* Technology", John Wily & Sons, Inc, 1981.
*/
#include <X11/Xos.h>
#include "Xlibint.h"
#include "Xcmsint.h"
/*
* EXTERNS
*/
extern char XcmsCIELuv_prefix[];
/*
* FORWARD DECLARATIONS
*/
static int CIELuv_ParseString();
Status XcmsCIELuv_ValidSpec();
/*
* DEFINES
* Internal definitions that need NOT be exported to any package
* or program using this package.
*/
#ifdef DBL_EPSILON
# define XMY_DBL_EPSILON DBL_EPSILON
#else
# define XMY_DBL_EPSILON 0.00001
#endif
/*
* LOCAL VARIABLES
*/
/*
* NULL terminated list of functions applied to get from CIELuv to CIEXYZ
*/
static XcmsConversionProc Fl_CIELuv_to_CIEXYZ[] = {
XcmsCIELuvToCIEuvY,
XcmsCIEuvYToCIEXYZ,
NULL
};
/*
* NULL terminated list of functions applied to get from CIEXYZ to CIELuv
*/
static XcmsConversionProc Fl_CIEXYZ_to_CIELuv[] = {
XcmsCIEXYZToCIEuvY,
XcmsCIEuvYToCIELuv,
NULL
};
/*
* GLOBALS
*/
/*
* CIE Luv Color Space
*/
XcmsColorSpace XcmsCIELuvColorSpace =
{
XcmsCIELuv_prefix, /* prefix */
XcmsCIELuvFormat, /* id */
CIELuv_ParseString, /* parseString */
Fl_CIELuv_to_CIEXYZ, /* to_CIEXYZ */
Fl_CIEXYZ_to_CIELuv, /* from_CIEXYZ */
1
};
/************************************************************************
* *
* PRIVATE ROUTINES *
* *
************************************************************************/
/*
* NAME
* CIELuv_ParseString
*
* SYNOPSIS
*/
static int
CIELuv_ParseString(spec, pColor)
register char *spec;
XcmsColor *pColor;
/*
* DESCRIPTION
* This routines takes a string and attempts to convert
* it into a XcmsColor structure with XcmsCIELuvFormat.
* The assumed CIELuv string syntax is:
* CIELuv:<L>/<u>/<v>
* Where L, u, and v are in string input format for floats
* consisting of:
* a. an optional sign
* b. a string of numbers possibly containing a decimal point,
* c. an optional exponent field containing an 'E' or 'e'
* followed by a possibly signed integer string.
*
* RETURNS
* 0 if failed, non-zero otherwise.
*/
{
int n;
char *pchar;
if ((pchar = strchr(spec, ':')) == NULL) {
return(XcmsFailure);
}
n = (int)(pchar - spec);
/*
* Check for proper prefix.
*/
if (strncmp(spec, XcmsCIELuv_prefix, n) != 0) {
return(XcmsFailure);
}
/*
* Attempt to parse the value portion.
*/
if (sscanf(spec + n + 1, "%lf/%lf/%lf",
&pColor->spec.CIELuv.L_star,
&pColor->spec.CIELuv.u_star,
&pColor->spec.CIELuv.v_star) != 3) {
return(XcmsFailure);
}
pColor->format = XcmsCIELuvFormat;
pColor->pixel = 0;
return(XcmsCIELuv_ValidSpec(pColor));
}
/************************************************************************
* *
* PUBLIC ROUTINES *
* *
************************************************************************/
/*
* NAME
* XcmsCIELuv_ValidSpec
*
* SYNOPSIS
*/
Status
XcmsCIELuv_ValidSpec(pColor)
XcmsColor *pColor;
/*
* DESCRIPTION
* Checks if color specification valid for CIE L*u*v*.
*
* RETURNS
* XcmsFailure if invalid,
* XcmsSuccess if valid.
*
*/
{
if (pColor->format != XcmsCIELuvFormat
||
(pColor->spec.CIELuv.L_star < 0.0 - XMY_DBL_EPSILON)
||
(pColor->spec.CIELuv.L_star > 100.0 + XMY_DBL_EPSILON)) {
return(XcmsFailure);
}
return(XcmsSuccess);
}
/*
* NAME
* XcmsCIELuvToCIEuvY - convert CIELuv to CIEuvY
*
* SYNOPSIS
*/
Status
XcmsCIELuvToCIEuvY(ccc, pLuv_WhitePt, pColors_in_out, nColors)
XcmsCCC ccc;
XcmsColor *pLuv_WhitePt;
XcmsColor *pColors_in_out;
unsigned int nColors;
/*
* DESCRIPTION
* Converts color specifications in an array of XcmsColor
* structures from CIELuv format to CIEuvY format.
*
* RETURNS
* XcmsFailure if failed,
* XcmsSuccess if succeeded.
*
*/
{
XcmsColor *pColor = pColors_in_out;
XcmsColor whitePt;
XcmsCIEuvY uvY_return;
XcmsFloat tmpVal;
register int i;
/*
* Check arguments
*/
if (pLuv_WhitePt == NULL || pColors_in_out == NULL) {
return(XcmsFailure);
}
/*
* Make sure white point is in CIEuvY form
*/
if (pLuv_WhitePt->format != XcmsCIEuvYFormat) {
/* Make copy of the white point because we're going to modify it */
bcopy((char *)pLuv_WhitePt, (char *)&whitePt, sizeof(XcmsColor));
if (!_XcmsDIConvertColors(ccc, &whitePt, (XcmsColor *)NULL,
1, XcmsCIEuvYFormat)) {
return(XcmsFailure);
}
pLuv_WhitePt = &whitePt;
}
/* Make sure it is a white point, i.e., Y == 1.0 */
if (pLuv_WhitePt->spec.CIEuvY.Y != 1.0) {
return(XcmsFailure);
}
/*
* Now convert each XcmsColor structure to CIEXYZ form
*/
for (i = 0; i < nColors; i++, pColor++) {
/* Make sure original format is CIELuv and is valid */
if (!XcmsCIELuv_ValidSpec(pColor)) {
return(XcmsFailure);
}
if (pColor->spec.CIELuv.L_star < 7.99953624) {
uvY_return.Y = pColor->spec.CIELuv.L_star / 903.29;
} else {
tmpVal = (pColor->spec.CIELuv.L_star + 16.0) / 116.0;
uvY_return.Y = tmpVal * tmpVal * tmpVal; /* tmpVal ** 3 */
}
if (pColor->spec.CIELuv.L_star == 0.0) {
uvY_return.u_prime = pLuv_WhitePt->spec.CIEuvY.u_prime;
uvY_return.v_prime = pLuv_WhitePt->spec.CIEuvY.v_prime;
} else {
tmpVal = 13.0 * (pColor->spec.CIELuv.L_star / 100.0);
uvY_return.u_prime = pColor->spec.CIELuv.u_star/tmpVal +
pLuv_WhitePt->spec.CIEuvY.u_prime;
uvY_return.v_prime = pColor->spec.CIELuv.v_star/tmpVal +
pLuv_WhitePt->spec.CIEuvY.v_prime;
}
/* Copy result to pColor */
bcopy ((char *)&uvY_return, (char *)&pColor->spec, sizeof(XcmsCIEuvY));
/* Identify that the format is now CIEuvY */
pColor->format = XcmsCIEuvYFormat;
}
return(XcmsSuccess);
}
/*
* NAME
* XcmsCIEuvYToCIELuv - convert CIEuvY to CIELuv
*
* SYNOPSIS
*/
Status
XcmsCIEuvYToCIELuv(ccc, pLuv_WhitePt, pColors_in_out, nColors)
XcmsCCC ccc;
XcmsColor *pLuv_WhitePt;
XcmsColor *pColors_in_out;
unsigned int nColors;
/*
* DESCRIPTION
* Converts color specifications in an array of XcmsColor
* structures from CIEuvY format to CIELab format.
*
* RETURNS
* XcmsFailure if failed,
* XcmsSuccess if succeeded.
*
*/
{
XcmsColor *pColor = pColors_in_out;
XcmsColor whitePt;
XcmsCIELuv Luv_return;
XcmsFloat tmpVal;
register int i;
/*
* Check arguments
*/
if (pLuv_WhitePt == NULL || pColors_in_out == NULL) {
return(XcmsFailure);
}
/*
* Make sure white point is in CIEuvY form
*/
if (pLuv_WhitePt->format != XcmsCIEuvYFormat) {
/* Make copy of the white point because we're going to modify it */
bcopy((char *)pLuv_WhitePt, (char *)&whitePt, sizeof(XcmsColor));
if (!_XcmsDIConvertColors(ccc, &whitePt,
(XcmsColor *)NULL, 1, XcmsCIEuvYFormat)) {
return(XcmsFailure);
}
pLuv_WhitePt = &whitePt;
}
/* Make sure it is a white point, i.e., Y == 1.0 */
if (pLuv_WhitePt->spec.CIEuvY.Y != 1.0) {
return(XcmsFailure);
}
/*
* Now convert each XcmsColor structure to CIEXYZ form
*/
for (i = 0; i < nColors; i++, pColor++) {
if (!XcmsCIEuvY_ValidSpec(pColor)) {
return(XcmsFailure);
}
/* Now convert the uvY to Luv */
Luv_return.L_star =
(pColor->spec.CIEuvY.Y < 0.008856)
?
(pColor->spec.CIEuvY.Y * 903.29)
:
((XcmsFloat)(XCMS_CUBEROOT(pColor->spec.CIEuvY.Y) * 116.0) - 16.0);
tmpVal = 13.0 * (Luv_return.L_star / 100.0);
Luv_return.u_star = tmpVal *
(pColor->spec.CIEuvY.u_prime - pLuv_WhitePt->spec.CIEuvY.u_prime);
Luv_return.v_star = tmpVal *
(pColor->spec.CIEuvY.v_prime - pLuv_WhitePt->spec.CIEuvY.v_prime);
/* Copy result to pColor */
bcopy ((char *)&Luv_return, (char *)&pColor->spec, sizeof(XcmsCIELuv));
/* Identify that the format is now CIEuvY */
pColor->format = XcmsCIELuvFormat;
}
return(XcmsSuccess);
}