/* $Xorg: Lab.c,v 1.3 2000/08/17 19:44:39 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 * CIELab.c * * DESCRIPTION * This file contains routines that support the CIE L*a*b* * color space to include conversions to and from the CIE * XYZ space. These conversions are from Principles of * Color Technology Second Edition, Fred W. Billmeyer, Jr. * and Max Saltzman, John Wiley & Sons, Inc., 1981. * * Note that the range for L* is 0 to 1. */ /* $XFree86: xc/lib/X11/Lab.c,v 1.3 2001/01/17 19:41:38 dawes Exp $ */ #include #include /* sscanf */ #include "Xlibint.h" #include "Xcmsint.h" #include "Cv.h" /* * DEFINES * Internal definitions that need NOT be exported to any package * or program using this package. */ #ifdef DBL_EPSILON # define XMY_DBL_EPSILON DBL_EPSILON #else # define XMY_DBL_EPSILON 0.00001 #endif #define DIV16BY116 0.137931 /* * FORWARD DECLARATIONS */ static int CIELab_ParseString(register char *spec, XcmsColor *pColor); static Status XcmsCIELab_ValidSpec(XcmsColor *pColor); /* * LOCAL VARIABLES */ /* * NULL terminated list of functions applied to get from CIELab to CIEXYZ */ static XcmsConversionProc Fl_CIELab_to_CIEXYZ[] = { XcmsCIELabToCIEXYZ, NULL }; /* * NULL terminated list of functions applied to get from CIEXYZ to CIELab */ static XcmsConversionProc Fl_CIEXYZ_to_CIELab[] = { XcmsCIEXYZToCIELab, NULL }; /* * GLOBALS */ /* * CIE Lab Color Space */ XcmsColorSpace XcmsCIELabColorSpace = { _XcmsCIELab_prefix, /* prefix */ XcmsCIELabFormat, /* id */ CIELab_ParseString, /* parseString */ Fl_CIELab_to_CIEXYZ, /* to_CIEXYZ */ Fl_CIEXYZ_to_CIELab, /* from_CIEXYZ */ 1 }; /************************************************************************ * * * PRIVATE ROUTINES * * * ************************************************************************/ /* * NAME * CIELab_ParseString * * SYNOPSIS */ static int CIELab_ParseString( register char *spec, XcmsColor *pColor) /* * DESCRIPTION * This routines takes a string and attempts to convert * it into a XcmsColor structure with XcmsCIELabFormat. * The assumed CIELab string syntax is: * CIELab:// * Where L, a, and b are in string input format for floats * consisting of: * a. an optional sign * b. a string of numbers possibly containing a decimal point, * c. an optional exponent field containing an 'E' or 'e' * followed by a possibly signed integer string. * * RETURNS * 0 if failed, non-zero otherwise. */ { int n; char *pchar; if ((pchar = strchr(spec, ':')) == NULL) { return(XcmsFailure); } n = (int)(pchar - spec); /* * Check for proper prefix. */ if (strncmp(spec, _XcmsCIELab_prefix, n) != 0) { return(XcmsFailure); } /* * Attempt to parse the value portion. */ if (sscanf(spec + n + 1, "%lf/%lf/%lf", &pColor->spec.CIELab.L_star, &pColor->spec.CIELab.a_star, &pColor->spec.CIELab.b_star) != 3) { return(XcmsFailure); } pColor->format = XcmsCIELabFormat; pColor->pixel = 0; return(XcmsCIELab_ValidSpec(pColor)); } /************************************************************************ * * * PUBLIC ROUTINES * * * ************************************************************************/ /* * NAME * XcmsCIELab_ValidSpec * * SYNOPSIS */ static Status XcmsCIELab_ValidSpec( XcmsColor *pColor) /* * DESCRIPTION * Checks if color specification valid for CIE L*a*b*. * * RETURNS * XcmsFailure if invalid, * XcmsSuccess if valid. * */ { if (pColor->format != XcmsCIELabFormat || (pColor->spec.CIELab.L_star < 0.0 - XMY_DBL_EPSILON) || (pColor->spec.CIELab.L_star > 100.0 + XMY_DBL_EPSILON)) { return(XcmsFailure); } return(XcmsSuccess); } /* * NAME * XcmsCIELabToCIEXYZ - convert CIELab to CIEXYZ * * SYNOPSIS */ Status XcmsCIELabToCIEXYZ(XcmsCCC ccc, XcmsColor *pLab_WhitePt, XcmsColor *pColors_in_out, unsigned int nColors) /* * DESCRIPTION * Converts color specifications in an array of XcmsColor * structures from CIELab format to CIEXYZ format. * * WARNING: This routine assumes that Yn = 1.0; * * RETURNS * XcmsFailure if failed, * XcmsSuccess if succeeded. * */ { XcmsCIEXYZ XYZ_return; XcmsFloat tmpFloat, tmpL; XcmsColor whitePt; int i; XcmsColor *pColor = pColors_in_out; /* * Check arguments */ if (pLab_WhitePt == NULL || pColors_in_out == NULL) { return(XcmsFailure); } /* * Make sure white point is in CIEXYZ form, if not, convert it. */ if (pLab_WhitePt->format != XcmsCIEXYZFormat) { /* Make a copy of the white point because we're going to modify it */ memcpy((char *)&whitePt, (char *)pLab_WhitePt, sizeof(XcmsColor)); if (!_XcmsDIConvertColors(ccc, &whitePt, (XcmsColor *)NULL, 1, XcmsCIEXYZFormat)) { return(XcmsFailure); } pLab_WhitePt = &whitePt; } /* * Make sure it is a white point, i.e., Y == 1.0 */ if (pLab_WhitePt->spec.CIEXYZ.Y != 1.0) { return (0); } /* * Now convert each XcmsColor structure to CIEXYZ form */ for (i = 0; i < nColors; i++, pColor++) { /* Make sure original format is CIELab */ if (!XcmsCIELab_ValidSpec(pColor)) { return(XcmsFailure); } /* Calculate Y: assume that Yn = 1.0 */ tmpL = (pColor->spec.CIELab.L_star + 16.0) / 116.0; XYZ_return.Y = tmpL * tmpL * tmpL; if (XYZ_return.Y < 0.008856) { /* Calculate Y: assume that Yn = 1.0 */ tmpL = pColor->spec.CIELab.L_star / 9.03292; /* Calculate X */ XYZ_return.X = pLab_WhitePt->spec.CIEXYZ.X * ((pColor->spec.CIELab.a_star / 3893.5) + tmpL); /* Calculate Y */ XYZ_return.Y = tmpL; /* Calculate Z */ XYZ_return.Z = pLab_WhitePt->spec.CIEXYZ.Z * (tmpL - (pColor->spec.CIELab.b_star / 1557.4)); } else { /* Calculate X */ tmpFloat = tmpL + (pColor->spec.CIELab.a_star / 5.0); XYZ_return.X = pLab_WhitePt->spec.CIEXYZ.X * tmpFloat * tmpFloat * tmpFloat; /* Calculate Z */ tmpFloat = tmpL - (pColor->spec.CIELab.b_star / 2.0); XYZ_return.Z = pLab_WhitePt->spec.CIEXYZ.Z * tmpFloat * tmpFloat * tmpFloat; } memcpy((char *)&pColor->spec.CIEXYZ, (char *)&XYZ_return, sizeof(XcmsCIEXYZ)); pColor->format = XcmsCIEXYZFormat; } return (1); } /* * NAME * XcmsCIEXYZToCIELab - convert CIEXYZ to CIELab * * SYNOPSIS */ Status XcmsCIEXYZToCIELab(XcmsCCC ccc, XcmsColor *pLab_WhitePt, XcmsColor *pColors_in_out, unsigned int nColors) /* * DESCRIPTION * Converts color specifications in an array of XcmsColor * structures from CIEXYZ format to CIELab format. * * WARNING: This routine assumes that Yn = 1.0; * * RETURNS * XcmsFailure if failed, * XcmsSuccess if succeeded. * */ { XcmsCIELab Lab_return; XcmsFloat fX_Xn, fY_Yn, fZ_Zn; XcmsColor whitePt; int i; XcmsColor *pColor = pColors_in_out; /* * Check arguments */ if (pLab_WhitePt == NULL || pColors_in_out == NULL) { return(XcmsFailure); } /* * Make sure white point is in CIEXYZ form, if not, convert it. */ if (pLab_WhitePt->format != XcmsCIEXYZFormat) { /* Make a copy of the white point because we're going to modify it */ memcpy((char *)&whitePt, (char *)pLab_WhitePt, sizeof(XcmsColor)); if (!_XcmsDIConvertColors(ccc, &whitePt, (XcmsColor *)NULL, 1, XcmsCIEXYZFormat)) { return(XcmsFailure); } pLab_WhitePt = &whitePt; } /* * Make sure it is a white point, i.e., Y == 1.0 */ if (pLab_WhitePt->spec.CIEXYZ.Y != 1.0) { return(XcmsFailure); } /* * Now convert each XcmsColor structure to CIEXYZ form */ for (i = 0; i < nColors; i++, pColor++) { /* Make sure original format is CIELab */ if (!_XcmsCIEXYZ_ValidSpec(pColor)) { return(XcmsFailure); } /* Calculate L*: assume Yn = 1.0 */ if (pColor->spec.CIEXYZ.Y < 0.008856) { fY_Yn = (0.07787 * pColor->spec.CIEXYZ.Y) + DIV16BY116; /* note fY_Yn used to compute Lab_return.a below */ Lab_return.L_star = 116.0 * (fY_Yn - DIV16BY116); } else { fY_Yn = (XcmsFloat)XCMS_CUBEROOT(pColor->spec.CIEXYZ.Y); /* note fY_Yn used to compute Lab_return.a_star below */ Lab_return.L_star = (116.0 * fY_Yn) - 16.0; } /* Calculate f(X/Xn) */ if ((fX_Xn = pColor->spec.CIEXYZ.X / pLab_WhitePt->spec.CIEXYZ.X) < 0.008856) { fX_Xn = (0.07787 * fX_Xn) + DIV16BY116; } else { fX_Xn = (XcmsFloat) XCMS_CUBEROOT(fX_Xn); } /* Calculate f(Z/Zn) */ if ((fZ_Zn = pColor->spec.CIEXYZ.Z / pLab_WhitePt->spec.CIEXYZ.Z) < 0.008856) { fZ_Zn = (0.07787 * fZ_Zn) + DIV16BY116; } else { fZ_Zn = (XcmsFloat) XCMS_CUBEROOT(fZ_Zn); } Lab_return.a_star = 5.0 * (fX_Xn - fY_Yn); Lab_return.b_star = 2.0 * (fY_Yn - fZ_Zn); memcpy((char *)&pColor->spec.CIELab, (char *)&Lab_return, sizeof(XcmsCIELab)); pColor->format = XcmsCIELabFormat; } return(XcmsSuccess); }