4.4BSD/usr/src/contrib/X11R5-lib/lib/X/CIELabGcL.c
/* $XConsortium: CIELabGcL.c,v 1.2 91/07/25 01:07:09 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
* CIELabGcL.c
*
* DESCRIPTION
* Source for XcmsCIELabClipL() gamut compression routine.
*
*/
#include "Xlibint.h"
#include "Xcmsint.h"
/*
* EXTERNS
*/
extern Status _XcmsCIELabQueryMaxLCRGB();
/************************************************************************
* *
* PUBLIC ROUTINES *
* *
************************************************************************/
/*
* NAME
* XcmsCIELabClipL - Return the closest L*
*
* SYNOPSIS
*/
/* ARGSUSED */
Status
XcmsCIELabClipL (ccc, pColors_in_out, nColors, i, pCompressed)
XcmsCCC ccc;
XcmsColor *pColors_in_out;
unsigned int nColors;
unsigned int i;
Bool *pCompressed;
/*
* DESCRIPTION
* Return the closest L* for a specific hue and chroma.
* This routine takes any color as input and outputs
* a CIE XYZ color.
*
* 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
*
*/
{
XcmsCCCRec myCCC;
XcmsColor *pColor;
XcmsColor Lab_max;
XcmsFloat hue, chroma, maxChroma;
Status retval;
/* Use my own CCC */
bcopy ((char *)ccc, (char *)&myCCC, sizeof(XcmsCCCRec));
myCCC.clientWhitePt.format = XcmsUndefinedFormat;/* Inherit Screen WP */
myCCC.gamutCompProc = (XcmsCompressionProc)NULL;/* no gamut compression */
/*
* 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 !
*/
return(XcmsFailure);
} else {
/* Convert from CIEXYZ to CIE L*u*v* format */
if (_XcmsDIConvertColors(&myCCC, pColor,
ScreenWhitePointOfCCC(&myCCC), 1, XcmsCIELabFormat)
== XcmsFailure) {
return(XcmsFailure);
}
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);
/* Step 1: compute the maximum L* and chroma for this hue. */
/* This copy may be overkill but it preserves the pixel etc. */
bcopy((char *)pColor, (char *)&Lab_max, sizeof(XcmsColor));
if (_XcmsCIELabQueryMaxLCRGB (&myCCC, hue, &Lab_max,
(XcmsRGBi *)NULL) == XcmsFailure) {
return (XcmsFailure);
}
maxChroma = XCMS_CIELAB_PMETRIC_CHROMA(Lab_max.spec.CIELab.a_star,
Lab_max.spec.CIELab.b_star);
/* Now check and return the appropriate L* */
if (chroma == maxChroma) {
/* When the chroma input is equal to the maximum chroma */
/* merely return the L* for that chroma. */
bcopy((char *)&Lab_max, (char *)pColor, sizeof(XcmsColor));
retval = _XcmsDIConvertColors(&myCCC, pColor,
ScreenWhitePointOfCCC(&myCCC), 1, XcmsCIEXYZFormat);
} else if (chroma > maxChroma) {
/* When the chroma input is greater than the maximum chroma */
/* merely return the L* and chroma for the given hue. */
bcopy((char *)&Lab_max, (char *)pColor, sizeof(XcmsColor));
return (XcmsFailure);
} else if (pColor->spec.CIELab.L_star < Lab_max.spec.CIELab.L_star) {
/* Find the minimum lightness for the given chroma. */
if (pColor->format != XcmsCIELabFormat) {
if (_XcmsDIConvertColors(ccc, pColor,
ScreenWhitePointOfCCC(ccc), 1, XcmsCIELabFormat)
== XcmsFailure) {
return(XcmsFailure);
}
}
if (XcmsCIELabQueryMinL(&myCCC, degrees(hue), chroma, pColor)
== XcmsFailure) {
return (XcmsFailure);
}
retval = _XcmsDIConvertColors(&myCCC, pColor,
ScreenWhitePointOfCCC(&myCCC), 1, XcmsCIEXYZFormat);
} else {
/* Find the maximum lightness for the given chroma. */
if (pColor->format != XcmsCIELabFormat) {
if (_XcmsDIConvertColors(ccc, pColor,
ScreenWhitePointOfCCC(ccc), 1, XcmsCIELabFormat)
== XcmsFailure) {
return(XcmsFailure);
}
}
if (XcmsCIELabQueryMaxL(&myCCC, degrees(hue), chroma, pColor)
== XcmsFailure) {
return (XcmsFailure);
}
retval = _XcmsDIConvertColors(&myCCC, pColor,
ScreenWhitePointOfCCC(&myCCC), 1, XcmsCIEXYZFormat);
}
if (retval != XcmsFailure && pCompressed != NULL) {
*(pCompressed + i) = True;
}
return(retval);
}
}