4.4BSD/usr/src/contrib/X11R5-lib/lib/X/CIELabGcLC.c
/* $XConsortium: CIELabGcLC.c,v 1.2 91/07/25 01:07:11 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
* CIELabGcLC.c
*
* DESCRIPTION
* Source for XcmsCIELabClipLab() gamut
* compression function.
*/
#include "Xlibint.h"
#include "Xcmsint.h"
#include <math.h>
/*
* INTERNALS
* Internal defines that need NOT be exported to any package or
* program using this package.
*/
#define MAXBISECTCOUNT 100
/*
* EXTERNS
*/
extern Status _XcmsCIELabQueryMaxLCRGB();
/************************************************************************
* *
* PUBLIC ROUTINES *
* *
************************************************************************/
/*
* NAME
* XcmsCIELabClipLab - Return the closest L* and chroma
*
* SYNOPSIS
*/
/* ARGSUSED */
Status
XcmsCIELabClipLab (ccc, pColors_in_out, nColors, i, pCompressed)
XcmsCCC ccc;
XcmsColor *pColors_in_out;
unsigned int nColors;
unsigned int i;
Bool *pCompressed;
/*
* DESCRIPTION
* This routine will find the closest L* and chroma
* for a specific hue. The color input is converted to
* CIE L*u*v* format and returned as CIE XYZ format.
*
* Since this routine works with the L* within
* pColor_in_out intermediate results may be returned
* even though it may be invalid.
*
* RETURNS
* XcmsFailure - Failure
* XcmsSuccess - Succeeded
*
*/
{
Status retval;
XcmsCCCRec myCCC;
XcmsColor *pColor;
XcmsColor Lab_max;
XcmsFloat hue, chroma, maxChroma;
XcmsFloat Chroma, bestChroma, Lstar, maxLstar, saveLstar;
XcmsFloat bestLstar, bestastar, bestbstar;
XcmsFloat nT, saveDist, tmpDist;
XcmsRGBi rgb_max;
int nCount, nMaxCount, nI, nILast;
/* Use my own CCC */
bcopy ((char *)ccc, (char *)&myCCC, sizeof(XcmsCCCRec));
myCCC.clientWhitePt.format = XcmsUndefinedFormat;/* inherit screen white */
myCCC.gamutCompProc = (XcmsCompressionProc)NULL;/* no gamut compression func */
/*
* Color specification passed as input can be assumed to:
* 1. Be in XcmsCIEXYZFormat
* 2. Already be white point adjusted for the Screen White Point.
* This means that the white point now associated with this
* color spec is the Screen White Point (even if the
* ccc->clientWhitePt differs).
*/
pColor = pColors_in_out + i;
if (ccc->visual->class < StaticColor) {
/*
* GRAY !
*/
_XcmsDIConvertColors(ccc, pColor, ScreenWhitePointOfCCC(ccc),
1, XcmsCIELabFormat);
_XcmsDIConvertColors(ccc, pColor, ScreenWhitePointOfCCC(ccc),
1, XcmsCIEXYZFormat);
if (pCompressed) {
*(pCompressed + i) = True;
}
return(XcmsSuccess);
}
/* Convert from CIEXYZ to CIELab format */
if (_XcmsDIConvertColors(&myCCC, pColor,
ScreenWhitePointOfCCC(&myCCC), 1, XcmsCIELabFormat)
== XcmsFailure) {
return(XcmsFailure);
}
/* Step 1: compute the maximum L* and chroma for this hue. */
/* This copy may be overkill but it preserves the pixel etc. */
saveLstar = pColor->spec.CIELab.L_star;
hue = XCMS_CIELAB_PMETRIC_HUE(pColor->spec.CIELab.a_star,
pColor->spec.CIELab.b_star);
chroma = XCMS_CIELAB_PMETRIC_CHROMA(pColor->spec.CIELab.a_star,
pColor->spec.CIELab.b_star);
bcopy((char *)pColor, (char *)&Lab_max, sizeof(XcmsColor));
if (_XcmsCIELabQueryMaxLCRGB (&myCCC, hue, &Lab_max, &rgb_max)
== XcmsFailure) {
return (XcmsFailure);
}
maxLstar = Lab_max.spec.CIELab.L_star;
/* Now check and return the appropriate L* */
if (saveLstar == maxLstar) {
/* When the L* input is equal to the maximum L* */
/* merely return the maximum Lab point. */
bcopy((char *)&Lab_max, (char *)pColor, sizeof(XcmsColor));
retval = _XcmsDIConvertColors(&myCCC, pColor,
ScreenWhitePointOfCCC(&myCCC), 1, XcmsCIEXYZFormat);
} else {
/* return the closest point on the hue leaf. */
/* must do a bisection here to compute the delta e. */
maxChroma = XCMS_CIELAB_PMETRIC_CHROMA(Lab_max.spec.CIELab.a_star,
Lab_max.spec.CIELab.b_star);
nMaxCount = MAXBISECTCOUNT;
nI = nMaxCount / 2;
bestLstar = Lstar = pColor->spec.CIELab.L_star;
bestastar = pColor->spec.CIELab.a_star;
bestbstar = pColor->spec.CIELab.b_star;
bestChroma = Chroma = chroma;
saveDist = XCMS_SQRT(((Chroma - maxChroma) * (Chroma - maxChroma)) +
((Lstar - maxLstar) * (Lstar - maxLstar)));
for (nCount = 0; nCount < nMaxCount; nCount++) {
nT = (XcmsFloat) nI / (XcmsFloat) nMaxCount;
if (saveLstar > maxLstar) {
pColor->spec.RGBi.red = rgb_max.red * (1.0 - nT) + nT;
pColor->spec.RGBi.green = rgb_max.green * (1.0 - nT) + nT;
pColor->spec.RGBi.blue = rgb_max.blue * (1.0 - nT) + nT;
} else {
pColor->spec.RGBi.red = rgb_max.red - (rgb_max.red * nT);
pColor->spec.RGBi.green = rgb_max.green - (rgb_max.green * nT);
pColor->spec.RGBi.blue = rgb_max.blue - (rgb_max.blue * nT);
}
pColor->format = XcmsRGBiFormat;
/* Convert from RGBi to CIE Lab */
if (_XcmsConvertColorsWithWhitePt(&myCCC, pColor,
ScreenWhitePointOfCCC(&myCCC), 1, XcmsCIELabFormat,
(Bool *) NULL) == XcmsFailure) {
return (XcmsFailure);
}
chroma = XCMS_CIELAB_PMETRIC_CHROMA(pColor->spec.CIELab.a_star,
pColor->spec.CIELab.b_star);
tmpDist = XCMS_SQRT(((Chroma - chroma) * (Chroma - chroma)) +
((Lstar - pColor->spec.CIELab.L_star) *
(Lstar - pColor->spec.CIELab.L_star)));
nILast = nI;
if (tmpDist > saveDist) {
nI /= 2;
} else {
nI = (nMaxCount + nI) / 2;
saveDist = tmpDist;
bestLstar = pColor->spec.CIELab.L_star;
bestastar = pColor->spec.CIELab.a_star;
bestbstar = pColor->spec.CIELab.b_star;
bestChroma = chroma;
}
if (nI == nILast || nI == 0) {
break;
}
}
if (bestChroma >= maxChroma) {
pColor->spec.CIELab.L_star = maxLstar;
pColor->spec.CIELab.a_star = Lab_max.spec.CIELab.a_star;
pColor->spec.CIELab.b_star = Lab_max.spec.CIELab.b_star;
} else {
pColor->spec.CIELab.L_star = bestLstar;
pColor->spec.CIELab.a_star = bestastar;
pColor->spec.CIELab.b_star = bestbstar;
}
retval = _XcmsDIConvertColors(&myCCC, pColor,
ScreenWhitePointOfCCC(&myCCC), 1, XcmsCIEXYZFormat);
if (retval != XcmsFailure && pCompressed != NULL) {
*(pCompressed + i) = True;
}
}
return(retval);
}