/* $XConsortium: LabMxL.c /main/4 1995/10/24 11:18:46 gildea $ */ /* * 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 * CIELabMxL.c * * DESCRIPTION * Source for the XcmsCIELabQueryMaxL() gamut boundary * querying routine. * */ /* $XFree86: xc/lib/X11/LabMxL.c,v 1.2 1999/05/09 10:49:43 dawes Exp $ */ #include "Xlibint.h" #include "Xcmsint.h" #include /* * DEFINES */ #define MAXBISECTCOUNT 100 #define EPS (XcmsFloat)0.001 #define START_L_STAR (XcmsFloat)40 /* * EXTERNS */ extern Status _XcmsCIELabQueryMaxLCRGB(); /* CvColW.c */ extern Status _XcmsConvertColorsWithWhitePt(); /************************************************************************ * * * PUBLIC ROUTINES * * * ************************************************************************/ /* * NAME * XcmsCIELabQueryMaxL - Compute max Lstar for a hue and chroma * * SYNOPSIS */ Status XcmsCIELabQueryMaxL(ccc, hue_angle, chroma, pColor_return) XcmsCCC ccc; XcmsFloat hue_angle; /* hue in degrees */ XcmsFloat chroma; XcmsColor *pColor_return; /* * DESCRIPTION * Return the maximum Lstar for a specified hue_angle and chroma. * * 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 with no modifications * */ { XcmsCCCRec myCCC; XcmsColor max_lc, tmp, prev; XcmsFloat max_chroma, tmp_chroma; XcmsFloat hue, nT, nChroma, lastChroma, prevChroma; XcmsFloat rFactor; XcmsRGBi rgb_saved; int nCount, nMaxCount; /* * Check Arguments */ if (ccc == NULL || pColor_return == NULL) { return(XcmsFailure); } /* setup the CCC to use for the conversions. */ memcpy ((char *) &myCCC, (char *) ccc, sizeof(XcmsCCCRec)); myCCC.clientWhitePt.format = XcmsUndefinedFormat; myCCC.gamutCompProc = (XcmsCompressionProc) NULL; while (hue_angle < 0.0) { hue_angle += 360.0; } while (hue_angle >= 360.0) { hue_angle -= 360.0; } hue = radians(hue_angle); tmp.spec.CIELab.L_star = START_L_STAR; tmp.spec.CIELab.a_star = XCMS_CIEASTAROFHUE(hue, chroma); tmp.spec.CIELab.b_star = XCMS_CIEBSTAROFHUE(hue, chroma); tmp.pixel = pColor_return->pixel; tmp.format = XcmsCIELabFormat; /* Step 1: Obtain the maximum L_star and chroma for this hue. */ if (_XcmsCIELabQueryMaxLCRGB(&myCCC, hue, &max_lc, &rgb_saved) == XcmsFailure) { return(XcmsFailure); } max_chroma = XCMS_CIELAB_PMETRIC_CHROMA(max_lc.spec.CIELab.a_star, max_lc.spec.CIELab.b_star); if (max_chroma <= chroma) { /* * If the chroma is greater than the chroma for the * maximum L/chroma point then the L_star is the * the L_star for the maximum L_star/chroma point. * This is an error but I return the best approximation I can. * Thus the inconsistency. */ memcpy ((char *) pColor_return, (char *) &max_lc, sizeof (XcmsColor)); return(XcmsSuccess); } /* * If the chroma is equal to the chroma for the * maximum L_star/chroma point then the L_star is the * the L_star for the maximum L* and chroma point. */ /* if (max_chroma == chroma) { * memcpy ((char *) pColor_return, (char *) &max_lc, sizeof (XcmsColor)); * return(XcmsSuccess); * } */ /* must do a bisection here to compute the maximum L* */ /* save the structure input so that any elements that */ /* are not touched are recopied later in the routine. */ nChroma = chroma; tmp_chroma = max_chroma; lastChroma = -1.0; nMaxCount = MAXBISECTCOUNT; rFactor = 1.0; for (nCount = 0; nCount < nMaxCount; nCount++) { prevChroma = lastChroma; lastChroma = tmp_chroma; nT = (1.0 - (nChroma / max_chroma)) * rFactor; memcpy ((char *)&prev, (char *)&tmp, sizeof(XcmsColor)); 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; tmp.format = XcmsRGBiFormat; /* convert from RGB to CIELab */ if (_XcmsConvertColorsWithWhitePt(&myCCC, &tmp, ScreenWhitePointOfCCC(&myCCC), 1, XcmsCIELabFormat, (Bool *) NULL) == XcmsFailure) { return(XcmsFailure); } /* Now check the return against what is expected */ tmp_chroma = XCMS_CIELAB_PMETRIC_CHROMA(tmp.spec.CIELab.a_star, tmp.spec.CIELab.b_star); if (tmp_chroma <= chroma + EPS && tmp_chroma >= chroma - EPS) { /* Found It! */ memcpy ((char *) pColor_return, (char *) &tmp, sizeof (XcmsColor)); return(XcmsSuccess); } nChroma += chroma - tmp_chroma; if (nChroma > max_chroma) { nChroma = max_chroma; rFactor *= 0.5; /* selective relaxation employed */ } else if (nChroma < 0.0) { if (XCMS_FABS(lastChroma - chroma) < XCMS_FABS(tmp_chroma - chroma)) { memcpy ((char *)pColor_return, (char *)&prev, sizeof(XcmsColor)); } else { memcpy ((char *)pColor_return, (char *)&tmp, sizeof(XcmsColor)); } return(XcmsSuccess); } else if (tmp_chroma <= prevChroma + EPS && tmp_chroma >= prevChroma - EPS) { rFactor *= 0.5; /* selective relaxation employed */ } } if (nCount >= nMaxCount) { if (XCMS_FABS(lastChroma - chroma) < XCMS_FABS(tmp_chroma - chroma)) { memcpy ((char *)pColor_return, (char *)&prev, sizeof(XcmsColor)); } else { memcpy ((char *)pColor_return, (char *)&tmp, sizeof(XcmsColor)); } } memcpy ((char *) pColor_return, (char *) &tmp, sizeof (XcmsColor)); return(XcmsSuccess); }