217 lines
6.6 KiB
C
217 lines
6.6 KiB
C
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/*
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* Code and supporting documentation (c) Copyright 1990 1991 Tektronix, Inc.
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* All Rights Reserved
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*
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* This file is a component of an X Window System-specific implementation
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* of XCMS based on the TekColor Color Management System. Permission is
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* hereby granted to use, copy, modify, sell, and otherwise distribute this
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* software and its documentation for any purpose and without fee, provided
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* that this copyright, permission, and disclaimer notice is reproduced in
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* all copies of this software and in supporting documentation. TekColor
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* is a trademark of Tektronix, Inc.
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*
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* Tektronix makes no representation about the suitability of this software
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* for any purpose. It is provided "as is" and with all faults.
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*
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* TEKTRONIX DISCLAIMS ALL WARRANTIES APPLICABLE TO THIS SOFTWARE,
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* INCLUDING THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
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* PARTICULAR PURPOSE. IN NO EVENT SHALL TEKTRONIX BE LIABLE FOR ANY
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* SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER
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* RESULTING FROM LOSS OF USE, DATA, OR PROFITS, WHETHER IN AN ACTION OF
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* CONTRACT, NEGLIGENCE, OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
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* CONNECTION WITH THE USE OR THE PERFORMANCE OF THIS SOFTWARE.
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*
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* NAME
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* CIELabMxL.c
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*
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* DESCRIPTION
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* Source for the XcmsCIELabQueryMaxL() gamut boundary
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* querying routine.
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*
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*/
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#ifdef HAVE_CONFIG_H
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#include <config.h>
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#endif
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#include "Xlibint.h"
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#include "Xcmsint.h"
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#include <math.h>
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#include "Cv.h"
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/*
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* DEFINES
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*/
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#define MAXBISECTCOUNT 100
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#define EPS (XcmsFloat)0.001
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#define START_L_STAR (XcmsFloat)40
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/************************************************************************
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* *
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* PUBLIC ROUTINES *
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* *
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************************************************************************/
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/*
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* NAME
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* XcmsCIELabQueryMaxL - Compute max Lstar for a hue and chroma
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*
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* SYNOPSIS
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*/
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Status
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XcmsCIELabQueryMaxL(
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XcmsCCC ccc,
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XcmsFloat hue_angle, /* hue in degrees */
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XcmsFloat chroma,
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XcmsColor *pColor_return)
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/*
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* DESCRIPTION
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* Return the maximum Lstar for a specified hue_angle and chroma.
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*
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* ASSUMPTIONS
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* This routine assumes that the white point associated with
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* the color specification is the Screen White Point. The
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* Screen White Point will also be associated with the
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* returned color specification.
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*
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* RETURNS
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* XcmsFailure - Failure
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* XcmsSuccess - Succeeded with no modifications
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*
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*/
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{
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XcmsCCCRec myCCC;
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XcmsColor max_lc, tmp, prev;
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XcmsFloat max_chroma, tmp_chroma;
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XcmsFloat hue, nT, nChroma, lastChroma, prevChroma;
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XcmsFloat rFactor;
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XcmsRGBi rgb_saved;
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int nCount, nMaxCount;
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/*
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* Check Arguments
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*/
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if (ccc == NULL || pColor_return == NULL) {
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return(XcmsFailure);
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}
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/* setup the CCC to use for the conversions. */
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memcpy ((char *) &myCCC, (char *) ccc, sizeof(XcmsCCCRec));
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myCCC.clientWhitePt.format = XcmsUndefinedFormat;
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myCCC.gamutCompProc = (XcmsCompressionProc) NULL;
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while (hue_angle < 0.0) {
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hue_angle += 360.0;
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}
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while (hue_angle >= 360.0) {
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hue_angle -= 360.0;
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}
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hue = radians(hue_angle);
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tmp.spec.CIELab.L_star = START_L_STAR;
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tmp.spec.CIELab.a_star = XCMS_CIEASTAROFHUE(hue, chroma);
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tmp.spec.CIELab.b_star = XCMS_CIEBSTAROFHUE(hue, chroma);
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tmp.pixel = pColor_return->pixel;
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tmp.format = XcmsCIELabFormat;
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/* Step 1: Obtain the maximum L_star and chroma for this hue. */
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if (_XcmsCIELabQueryMaxLCRGB(&myCCC, hue, &max_lc, &rgb_saved)
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== XcmsFailure) {
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return(XcmsFailure);
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}
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max_chroma = XCMS_CIELAB_PMETRIC_CHROMA(max_lc.spec.CIELab.a_star,
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max_lc.spec.CIELab.b_star);
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if (max_chroma <= chroma) {
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/*
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* If the chroma is greater than the chroma for the
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* maximum L/chroma point then the L_star is the
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* the L_star for the maximum L_star/chroma point.
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* This is an error but I return the best approximation I can.
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* Thus the inconsistency.
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*/
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memcpy ((char *) pColor_return, (char *) &max_lc, sizeof (XcmsColor));
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return(XcmsSuccess);
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}
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/*
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* If the chroma is equal to the chroma for the
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* maximum L_star/chroma point then the L_star is the
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* the L_star for the maximum L* and chroma point.
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*/
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/* if (max_chroma == chroma) {
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* memcpy ((char *) pColor_return, (char *) &max_lc, sizeof (XcmsColor));
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* return(XcmsSuccess);
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* }
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*/
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/* must do a bisection here to compute the maximum L* */
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/* save the structure input so that any elements that */
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/* are not touched are recopied later in the routine. */
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nChroma = chroma;
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tmp_chroma = max_chroma;
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lastChroma = -1.0;
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nMaxCount = MAXBISECTCOUNT;
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rFactor = 1.0;
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for (nCount = 0; nCount < nMaxCount; nCount++) {
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prevChroma = lastChroma;
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lastChroma = tmp_chroma;
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nT = (1.0 - (nChroma / max_chroma)) * rFactor;
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memcpy ((char *)&prev, (char *)&tmp, sizeof(XcmsColor));
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tmp.spec.RGBi.red = rgb_saved.red * (1.0 - nT) + nT;
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tmp.spec.RGBi.green = rgb_saved.green * (1.0 - nT) + nT;
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tmp.spec.RGBi.blue = rgb_saved.blue * (1.0 - nT) + nT;
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tmp.format = XcmsRGBiFormat;
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/* convert from RGB to CIELab */
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if (_XcmsConvertColorsWithWhitePt(&myCCC, &tmp,
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ScreenWhitePointOfCCC(&myCCC), 1, XcmsCIELabFormat,
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(Bool *) NULL) == XcmsFailure) {
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return(XcmsFailure);
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}
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/* Now check the return against what is expected */
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tmp_chroma = XCMS_CIELAB_PMETRIC_CHROMA(tmp.spec.CIELab.a_star,
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tmp.spec.CIELab.b_star);
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if (tmp_chroma <= chroma + EPS && tmp_chroma >= chroma - EPS) {
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/* Found It! */
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memcpy ((char *) pColor_return, (char *) &tmp, sizeof (XcmsColor));
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return(XcmsSuccess);
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}
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nChroma += chroma - tmp_chroma;
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if (nChroma > max_chroma) {
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nChroma = max_chroma;
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rFactor *= 0.5; /* selective relaxation employed */
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} else if (nChroma < 0.0) {
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if (XCMS_FABS(lastChroma - chroma) <
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XCMS_FABS(tmp_chroma - chroma)) {
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memcpy ((char *)pColor_return, (char *)&prev,
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sizeof(XcmsColor));
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} else {
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memcpy ((char *)pColor_return, (char *)&tmp,
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sizeof(XcmsColor));
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}
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return(XcmsSuccess);
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} else if (tmp_chroma <= prevChroma + EPS &&
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tmp_chroma >= prevChroma - EPS) {
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rFactor *= 0.5; /* selective relaxation employed */
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}
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}
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if (nCount >= nMaxCount) {
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if (XCMS_FABS(lastChroma - chroma) <
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XCMS_FABS(tmp_chroma - chroma)) {
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memcpy ((char *)pColor_return, (char *)&prev,
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sizeof(XcmsColor));
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} else {
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memcpy ((char *)pColor_return, (char *)&tmp,
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sizeof(XcmsColor));
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}
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}
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memcpy ((char *) pColor_return, (char *) &tmp, sizeof (XcmsColor));
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return(XcmsSuccess);
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}
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