4.4BSD/usr/src/contrib/X11R5-lib/lib/X/CIELuvMxC.c
/* $XConsortium: CIELuvMxC.c,v 1.2 91/07/25 01:07:40 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
* CIELuvMxC.c
*
* DESCRIPTION
* Source for the XcmsCIELuvQueryMaxC() gamut boundary
* querying routine.
*
*/
#include "Xlibint.h"
#include "Xcmsint.h"
#include <math.h>
/*
* DEFINES
*/
#define MAXBISECTCOUNT 100
#define EPS (XcmsFloat)0.001
#define START_CHROMA (XcmsFloat)2.2
#define TOPL (XcmsFloat)100.0
/*
* EXTERNS
*/
extern Status _XcmsCIELuvQueryMaxLCRGB();
/************************************************************************
* *
* PUBLIC ROUTINES *
* *
************************************************************************/
/*
* NAME
* XcmsCIELuvQueryMaxC - max chroma for a hue_angle and L_star
*
* SYNOPSIS
*/
Status
XcmsCIELuvQueryMaxC(ccc, hue_angle, L_star, pColor_return)
XcmsCCC ccc;
XcmsFloat hue_angle; /* hue angle in degrees */
XcmsFloat L_star;
XcmsColor *pColor_return;
/*
* DESCRIPTION
* Return the maximum chroma for a specific hue_angle and L_star.
* The returned format is in XcmsCIELuvFormat.
*
*
* ASSUMPTIONS
* This routine assumes that the white point associated with
* the color specification is the Screen White Point. The
* Screen White Point will also be associated with the
* returned color specification.
*
* RETURNS
* XcmsFailure - Failure
* XcmsSuccess - Succeeded
*
*/
{
XcmsCCCRec myCCC;
XcmsColor tmp;
XcmsColor max_lc;
XcmsFloat n_L_star, last_L_star, prev_L_star;
XcmsFloat hue, lastuStar, lastvStar, /*lastChroma,*/ maxDist, nT, rFactor;
XcmsRGBi rgb_saved;
int nCount, nMaxCount;
/*
* Check Arguments
*/
if (ccc == NULL || pColor_return == NULL) {
return(XcmsFailure);
}
/* Use my own CCC and inherit screen white Pt */
bcopy ((char *)ccc, (char *)&myCCC, sizeof(XcmsCCCRec));
myCCC.clientWhitePt.format = XcmsUndefinedFormat;
myCCC.gamutCompProc = (XcmsCompressionProc)NULL;/* no gamut comp func */
while (hue_angle < 0.0) {
hue_angle += 360.0;
}
while (hue_angle >= 360.0) {
hue_angle -= 360.0;
}
hue = radians(hue_angle);
tmp.spec.CIELuv.L_star = L_star;
tmp.spec.CIELuv.u_star = XCMS_CIEUSTAROFHUE(hue, START_CHROMA);
tmp.spec.CIELuv.v_star = XCMS_CIEVSTAROFHUE(hue, START_CHROMA);
tmp.pixel = pColor_return->pixel;
tmp.format = XcmsCIELuvFormat;
/* Step 1: compute the maximum L_star and chroma for this hue. */
bcopy((char *)&tmp, (char *)&max_lc, sizeof(XcmsColor));
if (_XcmsCIELuvQueryMaxLCRGB(&myCCC, hue, &max_lc, &rgb_saved)
== XcmsFailure) {
return(XcmsFailure);
}
/*
* Step 2: Do a bisection here to compute the maximum chroma
* Note the differences between when the point to be found
* is above the maximum LC point and when it is below.
*/
if (L_star <= max_lc.spec.CIELuv.L_star) {
maxDist = max_lc.spec.CIELuv.L_star;
} else {
maxDist = TOPL - max_lc.spec.CIELuv.L_star;
}
n_L_star = L_star;
last_L_star = -1.0;
nMaxCount = MAXBISECTCOUNT;
rFactor = 1.0;
for (nCount = 0; nCount < nMaxCount; nCount++) {
prev_L_star = last_L_star;
last_L_star = tmp.spec.CIELuv.L_star;
/* lastChroma = XCMS_CIELUV_PMETRIC_CHROMA(tmp.spec.CIELuv.u_star, */
/* tmp.spec.CIELuv.v_star); */
lastuStar = tmp.spec.CIELuv.u_star;
lastvStar = tmp.spec.CIELuv.v_star;
nT = (n_L_star - max_lc.spec.CIELuv.L_star) / maxDist * rFactor;
/* printf("(n_L_star, nT) = %lf %lf ", n_L_star, nT); */
if (nT > 0) {
tmp.spec.RGBi.red = rgb_saved.red * (1.0 - nT) + nT;
tmp.spec.RGBi.green = rgb_saved.green * (1.0 - nT) + nT;
tmp.spec.RGBi.blue = rgb_saved.blue * (1.0 - nT) + nT;
} else {
tmp.spec.RGBi.red = rgb_saved.red + (rgb_saved.red * nT);
tmp.spec.RGBi.green = rgb_saved.green + (rgb_saved.green * nT);
tmp.spec.RGBi.blue = rgb_saved.blue + (rgb_saved.blue * nT);
}
tmp.format = XcmsRGBiFormat;
/* convert from RGB to CIELuv */
if (_XcmsConvertColorsWithWhitePt(&myCCC, &tmp,
ScreenWhitePointOfCCC(&myCCC), 1, XcmsCIELuvFormat,
(Bool *) NULL) == XcmsFailure) {
return(XcmsFailure);
}
/*
* Now check if we've reached the target L_star
*/
/* printf("result Lstar = %lf\n", tmp.spec.CIELuv.L_star); */
if (tmp.spec.CIELuv.L_star <= L_star + EPS &&
tmp.spec.CIELuv.L_star >= L_star - EPS) {
bcopy((char *)&tmp, (char *)pColor_return, sizeof(XcmsColor));
return(XcmsSuccess);
}
if (nT > 0) {
n_L_star += ((TOPL - n_L_star) *
(L_star - tmp.spec.CIELuv.L_star)) / (TOPL - L_star);
} else {
n_L_star *= L_star / tmp.spec.CIELuv.L_star;
}
if (tmp.spec.CIELuv.L_star <= prev_L_star + EPS &&
tmp.spec.CIELuv.L_star >= prev_L_star - EPS) {
rFactor *= 0.5; /* selective relaxation employed */
/* printf("rFactor = %lf\n", rFactor); */
}
}
if (XCMS_FABS(last_L_star - L_star) <
XCMS_FABS(tmp.spec.CIELuv.L_star - L_star)) {
tmp.spec.CIELuv.u_star = lastuStar;
tmp.spec.CIELuv.v_star = lastvStar;
/* tmp.spec.CIELuv.u_star = XCMS_CIEUSTAROFHUE(hue, lastChroma); */
/* tmp.spec.CIELuv.v_star = XCMS_CIEVSTAROFHUE(hue, lastChroma); */
}
tmp.spec.CIELuv.L_star = L_star;
bcopy((char *)&tmp, (char *)pColor_return, sizeof(XcmsColor));
return(XcmsSuccess);
}