4.4BSD/usr/src/contrib/X11R5-lib/lib/X/CIEuvY.c
/* $XConsortium: CIEuvY.c,v 1.7 91/07/25 01:07:51 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
* CIEuvy.c
*
* DESCRIPTION
* This file contains routines that support the CIE u'v'Y
* color space to include conversions to and from the CIE
* XYZ space.
*
* DOCUMENTATION
* "TekColor Color Management System, System Implementor's Manual"
*/
#include <X11/Xos.h>
#include "Xlibint.h"
#include "Xcmsint.h"
/*
* EXTERNS
*/
extern char XcmsCIEuvY_prefix[];
/*
* FORWARD DECLARATIONS
*/
static int CIEuvY_ParseString();
Status XcmsCIEuvY_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 CIEuvY to CIEXYZ
*/
static XcmsConversionProc Fl_CIEuvY_to_CIEXYZ[] = {
XcmsCIEuvYToCIEXYZ,
NULL
};
/*
* NULL terminated list of functions applied to get from CIEXYZ to CIEuvY
*/
static XcmsConversionProc Fl_CIEXYZ_to_CIEuvY[] = {
XcmsCIEXYZToCIEuvY,
NULL
};
/*
* GLOBALS
*/
/*
* CIE uvY Color Space
*/
XcmsColorSpace XcmsCIEuvYColorSpace =
{
XcmsCIEuvY_prefix, /* prefix */
XcmsCIEuvYFormat, /* id */
CIEuvY_ParseString, /* parseString */
Fl_CIEuvY_to_CIEXYZ, /* to_CIEXYZ */
Fl_CIEXYZ_to_CIEuvY, /* from_CIEXYZ */
1
};
/************************************************************************
* *
* PRIVATE ROUTINES *
* *
************************************************************************/
/*
* NAME
* CIEuvY_ParseString
*
* SYNOPSIS
*/
static int
CIEuvY_ParseString(spec, pColor)
register char *spec;
XcmsColor *pColor;
/*
* DESCRIPTION
* This routines takes a string and attempts to convert
* it into a XcmsColor structure with XcmsCIEuvYFormat.
* The assumed CIEuvY string syntax is:
* CIEuvY:<u>/<v>/<Y>
* Where u, v, and Y 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, XcmsCIEuvY_prefix, n) != 0) {
return(XcmsFailure);
}
/*
* Attempt to parse the value portion.
*/
if (sscanf(spec + n + 1, "%lf/%lf/%lf",
&pColor->spec.CIEuvY.u_prime,
&pColor->spec.CIEuvY.v_prime,
&pColor->spec.CIEuvY.Y) != 3) {
return(XcmsFailure);
}
pColor->format = XcmsCIEuvYFormat;
pColor->pixel = 0;
return(XcmsCIEuvY_ValidSpec(pColor));
}
/************************************************************************
* *
* PUBLIC ROUTINES *
* *
************************************************************************/
/*
* NAME
* XcmsCIEuvY_ValidSpec
*
* SYNOPSIS
*/
Status
XcmsCIEuvY_ValidSpec(pColor)
XcmsColor *pColor;
/*
* DESCRIPTION
* Checks if color specification valid for CIE u'v'Y.
*
* RETURNS
* XcmsFailure if invalid,
* XcmsSuccess if valid.
*
*/
{
if (pColor->format != XcmsCIEuvYFormat
||
(pColor->spec.CIEuvY.Y < 0.0 - XMY_DBL_EPSILON)
||
(pColor->spec.CIEuvY.Y > 1.0 + XMY_DBL_EPSILON)) {
return(XcmsFailure);
}
return(XcmsSuccess);
}
/*
* NAME
* XcmsCIEuvYToCIEXYZ - convert CIEuvY to CIEXYZ
*
* SYNOPSIS
*/
Status
XcmsCIEuvYToCIEXYZ(ccc, puvY_WhitePt, pColors_in_out, nColors)
XcmsCCC ccc;
XcmsColor *puvY_WhitePt;
XcmsColor *pColors_in_out;
unsigned int nColors;
/*
* DESCRIPTION
* Converts color specifications in an array of XcmsColor
* structures from CIEuvY format to CIEXYZ format.
*
* RETURNS
* XcmsFailure if failed,
* XcmsSuccess if succeeded.
*
*/
{
XcmsCIEXYZ XYZ_return;
XcmsColor whitePt;
int i;
XcmsColor *pColor = pColors_in_out;
XcmsFloat div, x, y, z, Y;
/*
* Check arguments
* Postpone checking puvY_WhitePt until it is actually needed
* otherwise converting between XYZ and uvY will fail.
*/
if (pColors_in_out == NULL) {
return(XcmsFailure);
}
/*
* Now convert each XcmsColor structure to CIEXYZ form
*/
for (i = 0; i < nColors; i++, pColor++) {
/* Make sure original format is CIEuvY */
if (!XcmsCIEuvY_ValidSpec(pColor)) {
return(XcmsFailure);
}
/*
* Convert to CIEXYZ
*/
Y = pColor->spec.CIEuvY.Y;
/* Convert color u'v' to xyz space */
div = (6.0 * pColor->spec.CIEuvY.u_prime) - (16.0 * pColor->spec.CIEuvY.v_prime) + 12.0;
if (div == 0.0) {
/* use white point since div == 0 */
if (puvY_WhitePt == NULL ) {
return(XcmsFailure);
}
/*
* Make sure white point is in CIEuvY form
*/
if (puvY_WhitePt->format != XcmsCIEuvYFormat) {
/* Make copy of the white point because we're going to modify it */
bcopy((char *)puvY_WhitePt, (char *)&whitePt, sizeof(XcmsColor));
if (!_XcmsDIConvertColors(ccc, &whitePt, (XcmsColor *)NULL, 1,
XcmsCIEuvYFormat)) {
return(XcmsFailure);
}
puvY_WhitePt = &whitePt;
}
/* Make sure it is a white point, i.e., Y == 1.0 */
if (puvY_WhitePt->spec.CIEuvY.Y != 1.0) {
return(XcmsFailure);
}
div = (6.0 * puvY_WhitePt->spec.CIEuvY.u_prime) -
(16.0 * puvY_WhitePt->spec.CIEuvY.v_prime) + 12.0;
if (div == 0) {
/* internal error */
return(XcmsFailure);
}
x = 9.0 * puvY_WhitePt->spec.CIEuvY.u_prime / div;
y = 4.0 * puvY_WhitePt->spec.CIEuvY.v_prime / div;
} else {
x = 9.0 * pColor->spec.CIEuvY.u_prime / div;
y = 4.0 * pColor->spec.CIEuvY.v_prime / div;
}
z = 1.0 - x - y;
/* Convert from xyz to XYZ */
/* Conversion uses color normalized lightness based on Y */
if (y != 0.0) {
XYZ_return.X = x * Y / y;
} else {
XYZ_return.X = x;
}
XYZ_return.Y = Y;
if (y != 0.0) {
XYZ_return.Z = z * Y / y;
} else {
XYZ_return.Z = z;
}
bcopy((char *)&XYZ_return, (char *)&pColor->spec.CIEXYZ, sizeof(XcmsCIEXYZ));
/* Identify that format is now CIEXYZ */
pColor->format = XcmsCIEXYZFormat;
}
return(XcmsSuccess);
}
/*
* NAME
* XcmsCIEXYZToCIEuvY - convert CIEXYZ to CIEuvY
*
* SYNOPSIS
*/
Status
XcmsCIEXYZToCIEuvY(ccc, puvY_WhitePt, pColors_in_out, nColors)
XcmsCCC ccc;
XcmsColor *puvY_WhitePt;
XcmsColor *pColors_in_out;
unsigned int nColors;
/*
* DESCRIPTION
* Converts color specifications in an array of XcmsColor
* structures from CIEXYZ format to CIEuvY format.
*
* RETURNS
* XcmsFailure if failed,
* XcmsSuccess if succeeded.
*
*/
{
XcmsCIEuvY uvY_return;
XcmsColor whitePt;
int i;
XcmsColor *pColor = pColors_in_out;
XcmsFloat div;
/*
* Check arguments
* Postpone checking puvY_WhitePt until it is actually needed
* otherwise converting between XYZ and uvY will fail.
*/
if (pColors_in_out == NULL) {
return(XcmsFailure);
}
/*
* Now convert each XcmsColor structure to CIEuvY form
*/
for (i = 0; i < nColors; i++, pColor++) {
/* Make sure original format is CIEXYZ */
if (!XcmsCIEXYZ_ValidSpec(pColor)) {
return(XcmsFailure);
}
/* Convert to CIEuvY */
div = pColor->spec.CIEXYZ.X + (15.0 * pColor->spec.CIEXYZ.Y) +
(3.0 * pColor->spec.CIEXYZ.Z);
if (div == 0.0) {
/* Use white point since div == 0.0 */
if (puvY_WhitePt == NULL ) {
return(XcmsFailure);
}
/*
* Make sure white point is in CIEuvY form
*/
if (puvY_WhitePt->format != XcmsCIEuvYFormat) {
/* Make copy of the white point because we're going to modify it */
bcopy((char *)puvY_WhitePt, (char *)&whitePt, sizeof(XcmsColor));
if (!_XcmsDIConvertColors(ccc, &whitePt, (XcmsColor *)NULL, 1,
XcmsCIEuvYFormat)) {
return(XcmsFailure);
}
puvY_WhitePt = &whitePt;
}
/* Make sure it is a white point, i.e., Y == 1.0 */
if (puvY_WhitePt->spec.CIEuvY.Y != 1.0) {
return(XcmsFailure);
}
uvY_return.Y = pColor->spec.CIEXYZ.Y;
uvY_return.u_prime = puvY_WhitePt->spec.CIEuvY.u_prime;
uvY_return.v_prime = puvY_WhitePt->spec.CIEuvY.v_prime;
} else {
uvY_return.u_prime = 4.0 * pColor->spec.CIEXYZ.X / div;
uvY_return.v_prime = 9.0 * pColor->spec.CIEXYZ.Y / div;
uvY_return.Y = pColor->spec.CIEXYZ.Y;
}
bcopy((char *)&uvY_return, (char *)&pColor->spec.CIEuvY, sizeof(XcmsCIEuvY));
/* Identify that format is now CIEuvY */
pColor->format = XcmsCIEuvYFormat;
}
return(XcmsSuccess);
}