4.4BSD/usr/src/contrib/X11R5-lib/lib/X/TekHVC.c
/* $XConsortium: TekHVC.c,v 1.8 91/07/25 01:07:57 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. TekColor is a
* trademark of Tektronix, Inc. The term "TekHVC" designates a particular
* color space that is the subject of U.S. Patent No. 4,985,853 (equivalent
* foreign patents pending). 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:
*
* 1. This copyright, permission, and disclaimer notice is reproduced in
* all copies of this software and any modification thereof and in
* supporting documentation;
* 2. Any color-handling application which displays TekHVC color
* cooordinates identifies these as TekHVC color coordinates in any
* interface that displays these coordinates and in any associated
* documentation;
* 3. The term "TekHVC" is always used, and is only used, in association
* with the mathematical derivations of the TekHVC Color Space,
* including those provided in this file and any equivalent pathways and
* mathematical derivations, regardless of digital (e.g., floating point
* or integer) representation.
*
* 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
* TekHVC.c
*
* DESCRIPTION
* This file contains routines that support the TekHVC
* color space to include conversions to and from the CIE
* XYZ space.
*
* DOCUMENTATION
* "TekColor Color Management System, System Implementor's Manual"
*/
#include "Xlibint.h"
#include "Xcmsint.h"
#include <X11/Xos.h>
#include <math.h>
/*
* DEFINES
*/
#define u_BR 0.7127 /* u' Best Red */
#define v_BR 0.4931 /* v' Best Red */
#define EPS 0.001
#define CHROMA_SCALE_FACTOR 7.50725
#ifndef PI
# ifdef M_PI
# define PI M_PI
# else
# define PI 3.14159265358979323846264338327950
# endif
#endif
#ifndef degrees
# define degrees(r) ((XcmsFloat)(r) * 180.0 / PI)
#endif /* degrees */
#ifndef radians
# define radians(d) ((XcmsFloat)(d) * PI / 180.0)
#endif /* radians */
/*************************************************************************
* Note: The DBL_EPSILON for ANSI is 1e-5 so my checks need to take
* this into account. If your DBL_EPSILON is different then
* adjust this define.
*
* Also note that EPS is the error factor in the calculations
* This may need to be the same as XMY_DBL_EPSILON in
* some implementations.
**************************************************************************/
#ifdef DBL_EPSILON
# define XMY_DBL_EPSILON DBL_EPSILON
#else
# define XMY_DBL_EPSILON 0.00001
#endif
/*
* EXTERNS
*/
extern char XcmsTekHVC_prefix[];
/*
* FORWARD DECLARATIONS
*/
static int TekHVC_ParseString();
Status XcmsTekHVC_ValidSpec();
/*
* LOCAL VARIABLES
*/
/*
* NULL terminated list of functions applied to get from TekHVC to CIEXYZ
*/
static XcmsConversionProc Fl_TekHVC_to_CIEXYZ[] = {
XcmsTekHVCToCIEuvY,
XcmsCIEuvYToCIEXYZ,
NULL
};
/*
* NULL terminated list of functions applied to get from CIEXYZ to TekHVC
*/
static XcmsConversionProc Fl_CIEXYZ_to_TekHVC[] = {
XcmsCIEXYZToCIEuvY,
XcmsCIEuvYToTekHVC,
NULL
};
/*
* GLOBALS
*/
/*
* TekHVC Color Space
*/
XcmsColorSpace XcmsTekHVCColorSpace =
{
XcmsTekHVC_prefix, /* prefix */
XcmsTekHVCFormat, /* id */
TekHVC_ParseString, /* parseString */
Fl_TekHVC_to_CIEXYZ, /* to_CIEXYZ */
Fl_CIEXYZ_to_TekHVC, /* from_CIEXYZ */
1
};
/************************************************************************
* *
* PRIVATE ROUTINES *
* *
************************************************************************/
/*
* NAME
* TekHVC_ParseString
*
* SYNOPSIS
*/
static int
TekHVC_ParseString(spec, pColor)
register char *spec;
XcmsColor *pColor;
/*
* DESCRIPTION
* This routines takes a string and attempts to convert
* it into a XcmsColor structure with XcmsTekHVCFormat.
* The assumed TekHVC string syntax is:
* TekHVC:<H>/<V>/<C>
* Where H, V, and C 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
* XcmsFailure if invalid;
* XcmsSuccess if valid.
*/
{
int n;
char *pchar;
if ((pchar = strchr(spec, ':')) == NULL) {
return(XcmsFailure);
}
n = (int)(pchar - spec);
/*
* Check for proper prefix.
*/
if (strncmp(spec, XcmsTekHVC_prefix, n) != 0) {
return(XcmsFailure);
}
/*
* Attempt to parse the value portion.
*/
if (sscanf(spec + n + 1, "%lf/%lf/%lf",
&pColor->spec.TekHVC.H,
&pColor->spec.TekHVC.V,
&pColor->spec.TekHVC.C) != 3) {
return(XcmsFailure);
}
pColor->format = XcmsTekHVCFormat;
pColor->pixel = 0;
return(XcmsTekHVC_ValidSpec(pColor));
}
/*
* NAME
* ThetaOffset -- compute thetaOffset
*
* SYNOPSIS
*/
static int
ThetaOffset(pWhitePt, pThetaOffset)
XcmsColor *pWhitePt;
XcmsFloat *pThetaOffset;
/*
* DESCRIPTION
* This routine computes the theta offset of a given
* white point, i.e. XcmsColor. It is used in both this
* conversion and the printer conversions.
*
* RETURNS
* 0 if failed.
* 1 if succeeded with no modifications.
*
* ASSUMPTIONS
* Assumes:
* pWhitePt != NULL
* pWhitePt->format == XcmsCIEuvYFormat
*
*/
{
double div, slopeuv;
if (pWhitePt == NULL || pWhitePt->format != XcmsCIEuvYFormat) {
return(0);
}
if ((div = u_BR - pWhitePt->spec.CIEuvY.u_prime) == 0.0) {
return(0);
}
slopeuv = (v_BR - pWhitePt->spec.CIEuvY.v_prime) / div;
*pThetaOffset = degrees(XCMS_ATAN(slopeuv));
return(1);
}
/************************************************************************
* *
* PUBLIC ROUTINES *
* *
************************************************************************/
/*
* NAME
* XcmsTekHVC_ValidSpec()
*
* SYNOPSIS
*/
int
XcmsTekHVC_ValidSpec(pColor)
XcmsColor *pColor;
/*
* DESCRIPTION
* Checks if values in the color specification are valid.
* Also brings hue into the range 0.0 <= Hue < 360.0
*
* RETURNS
* 0 if not valid.
* 1 if valid.
*
*/
{
if (pColor->format != XcmsTekHVCFormat) {
return(XcmsFailure);
}
if (pColor->spec.TekHVC.V < (0.0 - XMY_DBL_EPSILON)
|| pColor->spec.TekHVC.V > (100.0 + XMY_DBL_EPSILON)
|| (pColor->spec.TekHVC.C < 0.0 - XMY_DBL_EPSILON)) {
return(XcmsFailure);
}
if (pColor->spec.TekHVC.V < 0.0) {
pColor->spec.TekHVC.V = 0.0 + XMY_DBL_EPSILON;
} else if (pColor->spec.TekHVC.V > 100.0) {
pColor->spec.TekHVC.V = 100.0 - XMY_DBL_EPSILON;
}
if (pColor->spec.TekHVC.C < 0.0) {
pColor->spec.TekHVC.C = 0.0 - XMY_DBL_EPSILON;
}
while (pColor->spec.TekHVC.H < 0.0) {
pColor->spec.TekHVC.H += 360.0;
}
while (pColor->spec.TekHVC.H >= 360.0) {
pColor->spec.TekHVC.H -= 360.0;
}
return(XcmsSuccess);
}
/*
* NAME
* XcmsTekHVCToCIEuvY - convert TekHVC to CIEuvY
*
* SYNOPSIS
*/
Status
XcmsTekHVCToCIEuvY(ccc, pHVC_WhitePt, pColors_in_out, nColors)
XcmsCCC ccc;
XcmsColor *pHVC_WhitePt;
XcmsColor *pColors_in_out;
unsigned int nColors;
/*
* DESCRIPTION
* Transforms an array of TekHVC color specifications, given
* their associated white point, to CIECIEuvY.color
* specifications.
*
* RETURNS
* XcmsFailure if failed, XcmsSuccess otherwise.
*
*/
{
XcmsFloat thetaOffset;
XcmsColor *pColor = pColors_in_out;
XcmsColor whitePt;
XcmsCIEuvY uvY_return;
XcmsFloat tempHue, u, v;
XcmsFloat tmpVal;
register int i;
/*
* Check arguments
*/
if (pHVC_WhitePt == NULL || pColors_in_out == NULL) {
return(XcmsFailure);
}
/*
* Make sure white point is in CIEuvY form
*/
if (pHVC_WhitePt->format != XcmsCIEuvYFormat) {
/* Make copy of the white point because we're going to modify it */
bcopy((char *)pHVC_WhitePt, (char *)&whitePt, sizeof(XcmsColor));
if (!_XcmsDIConvertColors(ccc, &whitePt, (XcmsColor *)NULL, 1,
XcmsCIEuvYFormat)) {
return(XcmsFailure);
}
pHVC_WhitePt = &whitePt;
}
/* Make sure it is a white point, i.e., Y == 1.0 */
if (pHVC_WhitePt->spec.CIEuvY.Y != 1.0) {
return(XcmsFailure);
}
/* Get the thetaOffset */
if (!ThetaOffset(pHVC_WhitePt, &thetaOffset)) {
return(XcmsFailure);
}
/*
* Now convert each XcmsColor structure to CIEXYZ form
*/
for (i = 0; i < nColors; i++, pColor++) {
/* Make sure original format is TekHVC and is valid */
if (!XcmsTekHVC_ValidSpec(pColor)) {
return(XcmsFailure);
}
if (pColor->spec.TekHVC.V == 0.0 || pColor->spec.TekHVC.V == 100.0) {
if (pColor->spec.TekHVC.V == 100.0) {
uvY_return.Y = 1.0;
} else { /* pColor->spec.TekHVC.V == 0.0 */
uvY_return.Y = 0.0;
}
uvY_return.u_prime = pHVC_WhitePt->spec.CIEuvY.u_prime;
uvY_return.v_prime = pHVC_WhitePt->spec.CIEuvY.v_prime;
} else {
/* Find the hue based on the white point offset */
tempHue = pColor->spec.TekHVC.H + thetaOffset;
while (tempHue < 0.0) {
tempHue += 360.0;
}
while (tempHue >= 360.0) {
tempHue -= 360.0;
}
tempHue = radians(tempHue);
/* Calculate u'v' for the obtained hue */
u = (XcmsFloat) ((XCMS_COS(tempHue) * pColor->spec.TekHVC.C) /
(pColor->spec.TekHVC.V * (double)CHROMA_SCALE_FACTOR));
v = (XcmsFloat) ((XCMS_SIN(tempHue) * pColor->spec.TekHVC.C) /
(pColor->spec.TekHVC.V * (double)CHROMA_SCALE_FACTOR));
/* Based on the white point get the offset from best red */
uvY_return.u_prime = u + pHVC_WhitePt->spec.CIEuvY.u_prime;
uvY_return.v_prime = v + pHVC_WhitePt->spec.CIEuvY.v_prime;
/* Calculate the Y value based on the L* = V. */
if (pColor->spec.TekHVC.V < 7.99953624) {
uvY_return.Y = pColor->spec.TekHVC.V / 903.29;
} else {
tmpVal = (pColor->spec.TekHVC.V + 16.0) / 116.0;
uvY_return.Y = tmpVal * tmpVal * tmpVal; /* tmpVal ** 3 */
}
}
/* 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
* XcmsCIEuvYToTekHVC - convert CIEuvY to TekHVC
*
* SYNOPSIS
*/
Status
XcmsCIEuvYToTekHVC(ccc, pHVC_WhitePt, pColors_in_out, nColors)
XcmsCCC ccc;
XcmsColor *pHVC_WhitePt;
XcmsColor *pColors_in_out;
unsigned int nColors;
/*
* DESCRIPTION
* Transforms an array of CIECIEuvY.color specifications, given
* their assiciated white point, to TekHVC specifications.
*
* RETURNS
* XcmsFailure if failed, XcmsSuccess otherwise.
*
*/
{
XcmsFloat theta, L2, u, v, nThetaLow, nThetaHigh;
XcmsFloat thetaOffset;
XcmsColor *pColor = pColors_in_out;
XcmsColor whitePt;
XcmsTekHVC HVC_return;
register int i;
/*
* Check arguments
*/
if (pHVC_WhitePt == NULL || pColors_in_out == NULL) {
return(XcmsFailure);
}
/*
* Make sure white point is in CIEuvY form
*/
if (pHVC_WhitePt->format != XcmsCIEuvYFormat) {
/* Make copy of the white point because we're going to modify it */
bcopy((char *)pHVC_WhitePt, (char *)&whitePt, sizeof(XcmsColor));
if (!_XcmsDIConvertColors(ccc, &whitePt, (XcmsColor *)NULL, 1,
XcmsCIEuvYFormat)) {
return(XcmsFailure);
}
pHVC_WhitePt = &whitePt;
}
/* Make sure it is a white point, i.e., Y == 1.0 */
if (pHVC_WhitePt->spec.CIEuvY.Y != 1.0) {
return(XcmsFailure);
}
if (!ThetaOffset(pHVC_WhitePt, &thetaOffset)) {
return(XcmsFailure);
}
/*
* Now convert each XcmsColor structure to CIEXYZ form
*/
for (i = 0; i < nColors; i++, pColor++) {
if (!XcmsCIEuvY_ValidSpec(pColor)) {
return(XcmsFailure);
}
/* Use the white point offset to determine HVC */
u = pColor->spec.CIEuvY.u_prime - pHVC_WhitePt->spec.CIEuvY.u_prime;
v = pColor->spec.CIEuvY.v_prime - pHVC_WhitePt->spec.CIEuvY.v_prime;
/* Calculate the offset */
if (u == 0.0) {
theta = 0.0;
} else {
theta = v / u;
theta = (XcmsFloat) XCMS_ATAN((double)theta);
theta = degrees(theta);
}
nThetaLow = 0.0;
nThetaHigh = 360.0;
if (u > 0.0 && v > 0.0) {
nThetaLow = 0.0;
nThetaHigh = 90.0;
} else if (u < 0.0 && v > 0.0) {
nThetaLow = 90.0;
nThetaHigh = 180.0;
} else if (u < 0.0 && v < 0.0) {
nThetaLow = 180.0;
nThetaHigh = 270.0;
} else if (u > 0.0 && v < 0.0) {
nThetaLow = 270.0;
nThetaHigh = 360.0;
}
while (theta < nThetaLow) {
theta += 90.0;
}
while (theta >= nThetaHigh) {
theta -= 90.0;
}
/* calculate the L value from the given Y */
L2 = (pColor->spec.CIEuvY.Y < 0.008856)
?
(pColor->spec.CIEuvY.Y * 903.29)
:
((XcmsFloat)(XCMS_CUBEROOT(pColor->spec.CIEuvY.Y) * 116.0) - 16.0);
HVC_return.C = L2 * CHROMA_SCALE_FACTOR * XCMS_SQRT((double) ((u * u) + (v * v)));
if (HVC_return.C < 0.0) {
theta = 0.0;
}
HVC_return.V = L2;
HVC_return.H = theta - thetaOffset;
/*
* If this is within the error margin let some other routine later
* in the chain worry about the slop in the calculations.
*/
while (HVC_return.H < -EPS) {
HVC_return.H += 360.0;
}
while (HVC_return.H >= 360.0 + EPS) {
HVC_return.H -= 360.0;
}
/* Copy result to pColor */
bcopy ((char *)&HVC_return, (char *)&pColor->spec, sizeof(XcmsTekHVC));
/* Identify that the format is now CIEuvY */
pColor->format = XcmsTekHVCFormat;
}
return(XcmsSuccess);
}
/*
* NAME
* _XcmsTekHVC_CheckModify
*
* SYNOPSIS
*/
int
_XcmsTekHVC_CheckModify(pColor)
XcmsColor *pColor;
/*
* DESCRIPTION
* Checks if values in the color specification are valid.
* If they are not it modifies the values.
* Also brings hue into the range 0.0 <= Hue < 360.0
*
* RETURNS
* 0 if not valid.
* 1 if valid.
*
*/
{
/* For now only use the TekHVC numbers as inputs */
if (pColor->format != XcmsTekHVCFormat) {
return(0);
}
if (pColor->spec.TekHVC.V < 0.0) {
pColor->spec.TekHVC.V = 0.0 + XMY_DBL_EPSILON;
} else if (pColor->spec.TekHVC.V > 100.0) {
pColor->spec.TekHVC.V = 100.0 - XMY_DBL_EPSILON;
}
if (pColor->spec.TekHVC.C < 0.0) {
pColor->spec.TekHVC.C = 0.0 - XMY_DBL_EPSILON;
}
while (pColor->spec.TekHVC.H < 0.0) {
pColor->spec.TekHVC.H += 360.0;
}
while (pColor->spec.TekHVC.H >= 360.0) {
pColor->spec.TekHVC.H -= 360.0;
}
return(1);
}