diff options
Diffstat (limited to 'libX11/src/xcms/Lab.c')
| -rw-r--r-- | libX11/src/xcms/Lab.c | 862 |
1 files changed, 431 insertions, 431 deletions
diff --git a/libX11/src/xcms/Lab.c b/libX11/src/xcms/Lab.c index 1101754d4..02c8d3b7c 100644 --- a/libX11/src/xcms/Lab.c +++ b/libX11/src/xcms/Lab.c @@ -1,431 +1,431 @@ -
-/*
- * 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.
- */
-
-
-#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) {
- char *s; /* Maybe failed due to locale */
- int f;
- if ((s = strdup(spec))) {
- for (f = 0; s[f]; ++f)
- if (s[f] == '.')
- s[f] = ',';
- else if (s[f] == ',')
- s[f] = '.';
- if (sscanf(s + n + 1, "%lf/%lf/%lf",
- &pColor->spec.CIELab.L_star,
- &pColor->spec.CIELab.a_star,
- &pColor->spec.CIELab.b_star) != 3) {
- free(s);
- return(XcmsFailure);
- }
- free(s);
- } else
- 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);
-}
+ +/* + * 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. + */ + + +#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) { + char *s; /* Maybe failed due to locale */ + int f; + if ((s = strdup(spec))) { + for (f = 0; s[f]; ++f) + if (s[f] == '.') + s[f] = ','; + else if (s[f] == ',') + s[f] = '.'; + if (sscanf(s + n + 1, "%lf/%lf/%lf", + &pColor->spec.CIELab.L_star, + &pColor->spec.CIELab.a_star, + &pColor->spec.CIELab.b_star) != 3) { + free(s); + return(XcmsFailure); + } + free(s); + } else + 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); +} |