/* $Xorg: LabMxLC.c,v 1.3 2000/08/17 19:44:40 cpqbld 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 * CIELabMxVC.c * * DESCRIPTION * Source for the XcmsCIELabQueryMaxLC() gamut boundary * querying routine. * * DOCUMENTATION * "TekColor Color Management System, System Implementor's Manual" * and * Fred W. Billmeyer & Max Saltzman, "Principles of Color * Technology", John Wily & Sons, Inc, 1981. */ #include "Xlibint.h" #include "Xcmsint.h" /* * DEFINES */ #define MIN(x,y) ((x) > (y) ? (y) : (x)) #define MIN3(x,y,z) ((x) > (MIN((y), (z))) ? (MIN((y), (z))) : (x)) #define MAX(x,y) ((x) > (y) ? (x) : (y)) #define MAX3(x,y,z) ((x) > (MAX((y), (z))) ? (x) : (MAX((y), (z)))) #define START_LSTAR (XcmsFloat)40.0 #define START_CHROMA (XcmsFloat)3.6 /* * EXTERNS */ extern Status _XcmsConvertColorsWithWhitePt(); /* * FORWARD DECLARATIONS */ Status _XcmsCIELabQueryMaxLCRGB(); /************************************************************************ * * * API PRIVATE ROUTINES * * * ************************************************************************/ /* * NAME * _XcmsCIELabQueryMaxLCRGB - Compute maximum L* and chroma. * * SYNOPSIS */ Status _XcmsCIELabQueryMaxLCRGB(ccc, hue, pColor_return, pRGB_return) XcmsCCC ccc; XcmsFloat hue; /* hue in radians */ XcmsColor *pColor_return; XcmsRGBi *pRGB_return; /* * DESCRIPTION * Return the maximum psychometric chroma for a specified * hue, and the corresponding L*. This is computed * by a binary search of all possible chromas. An assumption * is made that there are no local maxima. Use the unrounded * Max psychometric chroma because the difference check can be * small. * * NOTE: No local CCC is used because this is a private * routine and all routines that call it are expected * to behave properly, i.e. send a local CCC with * no white adjust function and no gamut compression * function. * * This routine only accepts hue in radians as input and outputs * Lab and RGBi. * * RETURNS * XcmsFailure - Failure * XcmsSuccess - Succeeded * */ { XcmsFloat nSmall, nLarge; XcmsColor tmp; tmp.format = XcmsCIELabFormat; /* Use some unreachable color on the given hue */ tmp.spec.CIELab.L_star = START_LSTAR; tmp.spec.CIELab.a_star = XCMS_CIEASTAROFHUE(hue, START_CHROMA); tmp.spec.CIELab.b_star = XCMS_CIEBSTAROFHUE(hue, START_CHROMA); /* * Convert from Lab to RGB * * Note that the CIEXYZ to RGBi conversion routine must stuff the * out of bounds RGBi values in tmp when the ccc->gamutCompProc * is NULL. */ if ((_XcmsConvertColorsWithWhitePt(ccc, &tmp, ScreenWhitePointOfCCC(ccc), (unsigned int)1, XcmsRGBiFormat, (Bool *) NULL) == XcmsFailure) && tmp.format != XcmsRGBiFormat) { return (XcmsFailure); } /* Now pick the smallest RGB */ nSmall = MIN3(tmp.spec.RGBi.red, tmp.spec.RGBi.green, tmp.spec.RGBi.blue); /* Make the smallest RGB equal to zero */ tmp.spec.RGBi.red -= nSmall; tmp.spec.RGBi.green -= nSmall; tmp.spec.RGBi.blue -= nSmall; /* Now pick the largest RGB */ nLarge = MAX3(tmp.spec.RGBi.red, tmp.spec.RGBi.green, tmp.spec.RGBi.blue); /* Scale the RGB values based on the largest one */ tmp.spec.RGBi.red /= nLarge; tmp.spec.RGBi.green /= nLarge; tmp.spec.RGBi.blue /= nLarge; tmp.format = XcmsRGBiFormat; /* If the calling routine wants RGB value give them the ones used. */ if (pRGB_return) { pRGB_return->red = tmp.spec.RGBi.red; pRGB_return->green = tmp.spec.RGBi.green; pRGB_return->blue = tmp.spec.RGBi.blue; } /* Convert from RGBi to Lab */ if (_XcmsConvertColorsWithWhitePt(ccc, &tmp, ScreenWhitePointOfCCC(ccc), 1, XcmsCIELabFormat, (Bool *) NULL) == XcmsFailure) { return (XcmsFailure); } memcpy((char *)pColor_return, (char *)&tmp, sizeof(XcmsColor)); return (XcmsSuccess); } /************************************************************************ * * * PUBLIC ROUTINES * * * ************************************************************************/ /* * NAME * XcmsCIELabQueryMaxLC - Compute maximum L* and chroma. * * SYNOPSIS */ Status XcmsCIELabQueryMaxLC (ccc, hue_angle, pColor_return) XcmsCCC ccc; XcmsFloat hue_angle; /* hue_angle in degrees */ XcmsColor *pColor_return; /* * DESCRIPTION * Return the point of maximum chroma for the specified * hue_angle. * * 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; /* * Check Arguments */ if (ccc == NULL || pColor_return == NULL) { return(XcmsFailure); } /* Use my own CCC */ 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; } return(_XcmsCIELabQueryMaxLCRGB (&myCCC, radians(hue_angle), pColor_return, (XcmsRGBi *)NULL)); }