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+/* $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 $ */
+
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+#include <X11/Xos.h>
+#include <stdio.h> /* 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:<L>/<a>/<b>
+ * 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(ccc, pLab_WhitePt, pColors_in_out, nColors)
+ 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(ccc, pLab_WhitePt, pColors_in_out, nColors)
+ 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);
+}
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