432 lines
11 KiB
C
432 lines
11 KiB
C
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/*
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* Code and supporting documentation (c) Copyright 1990 1991 Tektronix, Inc.
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* All Rights Reserved
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*
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* This file is a component of an X Window System-specific implementation
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* of XCMS based on the TekColor Color Management System. Permission is
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* hereby granted to use, copy, modify, sell, and otherwise distribute this
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* software and its documentation for any purpose and without fee, provided
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* that this copyright, permission, and disclaimer notice is reproduced in
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* all copies of this software and in supporting documentation. TekColor
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* is a trademark of Tektronix, Inc.
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*
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* Tektronix makes no representation about the suitability of this software
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* for any purpose. It is provided "as is" and with all faults.
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*
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* TEKTRONIX DISCLAIMS ALL WARRANTIES APPLICABLE TO THIS SOFTWARE,
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* INCLUDING THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
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* PARTICULAR PURPOSE. IN NO EVENT SHALL TEKTRONIX BE LIABLE FOR ANY
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* SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER
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* RESULTING FROM LOSS OF USE, DATA, OR PROFITS, WHETHER IN AN ACTION OF
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* CONTRACT, NEGLIGENCE, OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
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* CONNECTION WITH THE USE OR THE PERFORMANCE OF THIS SOFTWARE.
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*
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*
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* NAME
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* CIELab.c
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*
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* DESCRIPTION
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* This file contains routines that support the CIE L*a*b*
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* color space to include conversions to and from the CIE
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* XYZ space. These conversions are from Principles of
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* Color Technology Second Edition, Fred W. Billmeyer, Jr.
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* and Max Saltzman, John Wiley & Sons, Inc., 1981.
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*
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* Note that the range for L* is 0 to 1.
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*/
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#ifdef HAVE_CONFIG_H
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#include <config.h>
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#endif
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#include <X11/Xos.h>
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#include <stdio.h> /* sscanf */
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#include "Xlibint.h"
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#include "Xcmsint.h"
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#include "Cv.h"
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/*
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* DEFINES
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* Internal definitions that need NOT be exported to any package
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* or program using this package.
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*/
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#ifdef DBL_EPSILON
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# define XMY_DBL_EPSILON DBL_EPSILON
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#else
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# define XMY_DBL_EPSILON 0.00001
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#endif
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#define DIV16BY116 0.137931
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/*
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* FORWARD DECLARATIONS
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*/
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static int CIELab_ParseString(register char *spec, XcmsColor *pColor);
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static Status XcmsCIELab_ValidSpec(XcmsColor *pColor);
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/*
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* LOCAL VARIABLES
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*/
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/*
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* NULL terminated list of functions applied to get from CIELab to CIEXYZ
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*/
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static XcmsConversionProc Fl_CIELab_to_CIEXYZ[] = {
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XcmsCIELabToCIEXYZ,
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NULL
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};
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/*
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* NULL terminated list of functions applied to get from CIEXYZ to CIELab
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*/
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static XcmsConversionProc Fl_CIEXYZ_to_CIELab[] = {
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XcmsCIEXYZToCIELab,
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NULL
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};
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/*
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* GLOBALS
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*/
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/*
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* CIE Lab Color Space
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*/
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XcmsColorSpace XcmsCIELabColorSpace =
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{
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_XcmsCIELab_prefix, /* prefix */
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XcmsCIELabFormat, /* id */
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CIELab_ParseString, /* parseString */
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Fl_CIELab_to_CIEXYZ, /* to_CIEXYZ */
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Fl_CIEXYZ_to_CIELab, /* from_CIEXYZ */
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1
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};
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/************************************************************************
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* *
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* PRIVATE ROUTINES *
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* *
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************************************************************************/
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/*
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* NAME
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* CIELab_ParseString
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*
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* SYNOPSIS
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*/
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static int
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CIELab_ParseString(
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register char *spec,
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XcmsColor *pColor)
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/*
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* DESCRIPTION
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* This routines takes a string and attempts to convert
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* it into a XcmsColor structure with XcmsCIELabFormat.
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* The assumed CIELab string syntax is:
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* CIELab:<L>/<a>/<b>
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* Where L, a, and b are in string input format for floats
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* consisting of:
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* a. an optional sign
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* b. a string of numbers possibly containing a decimal point,
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* c. an optional exponent field containing an 'E' or 'e'
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* followed by a possibly signed integer string.
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*
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* RETURNS
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* 0 if failed, non-zero otherwise.
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*/
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{
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int n;
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char *pchar;
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if ((pchar = strchr(spec, ':')) == NULL) {
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return(XcmsFailure);
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}
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n = (int)(pchar - spec);
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/*
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* Check for proper prefix.
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*/
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if (strncmp(spec, _XcmsCIELab_prefix, (size_t)n) != 0) {
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return(XcmsFailure);
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}
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/*
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* Attempt to parse the value portion.
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*/
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if (sscanf(spec + n + 1, "%lf/%lf/%lf",
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&pColor->spec.CIELab.L_star,
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&pColor->spec.CIELab.a_star,
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&pColor->spec.CIELab.b_star) != 3) {
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char *s; /* Maybe failed due to locale */
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int f;
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if ((s = strdup(spec))) {
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for (f = 0; s[f]; ++f)
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if (s[f] == '.')
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s[f] = ',';
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else if (s[f] == ',')
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s[f] = '.';
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if (sscanf(s + n + 1, "%lf/%lf/%lf",
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&pColor->spec.CIELab.L_star,
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&pColor->spec.CIELab.a_star,
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&pColor->spec.CIELab.b_star) != 3) {
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free(s);
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return(XcmsFailure);
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}
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free(s);
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} else
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return(XcmsFailure);
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}
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pColor->format = XcmsCIELabFormat;
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pColor->pixel = 0;
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return(XcmsCIELab_ValidSpec(pColor));
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}
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/************************************************************************
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* *
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* PUBLIC ROUTINES *
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* *
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************************************************************************/
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/*
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* NAME
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* XcmsCIELab_ValidSpec
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*
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* SYNOPSIS
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*/
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static Status
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XcmsCIELab_ValidSpec(
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XcmsColor *pColor)
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/*
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* DESCRIPTION
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* Checks if color specification valid for CIE L*a*b*.
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*
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* RETURNS
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* XcmsFailure if invalid,
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* XcmsSuccess if valid.
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*
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*/
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{
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if (pColor->format != XcmsCIELabFormat
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(pColor->spec.CIELab.L_star < 0.0 - XMY_DBL_EPSILON)
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(pColor->spec.CIELab.L_star > 100.0 + XMY_DBL_EPSILON)) {
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return(XcmsFailure);
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}
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return(XcmsSuccess);
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}
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/*
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* NAME
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* XcmsCIELabToCIEXYZ - convert CIELab to CIEXYZ
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*
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* SYNOPSIS
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*/
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Status
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XcmsCIELabToCIEXYZ(
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XcmsCCC ccc,
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XcmsColor *pLab_WhitePt,
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XcmsColor *pColors_in_out,
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unsigned int nColors)
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/*
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* DESCRIPTION
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* Converts color specifications in an array of XcmsColor
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* structures from CIELab format to CIEXYZ format.
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*
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* WARNING: This routine assumes that Yn = 1.0;
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*
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* RETURNS
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* XcmsFailure if failed,
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* XcmsSuccess if succeeded.
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*
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*/
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{
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XcmsCIEXYZ XYZ_return;
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XcmsFloat tmpFloat, tmpL;
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XcmsColor whitePt;
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unsigned int i;
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XcmsColor *pColor = pColors_in_out;
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/*
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* Check arguments
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*/
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if (pLab_WhitePt == NULL || pColors_in_out == NULL) {
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return(XcmsFailure);
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}
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/*
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* Make sure white point is in CIEXYZ form, if not, convert it.
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*/
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if (pLab_WhitePt->format != XcmsCIEXYZFormat) {
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/* Make a copy of the white point because we're going to modify it */
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memcpy((char *)&whitePt, (char *)pLab_WhitePt, sizeof(XcmsColor));
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if (!_XcmsDIConvertColors(ccc, &whitePt,
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(XcmsColor *)NULL, 1, XcmsCIEXYZFormat)) {
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return(XcmsFailure);
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}
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pLab_WhitePt = &whitePt;
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}
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/*
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* Make sure it is a white point, i.e., Y == 1.0
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*/
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if (pLab_WhitePt->spec.CIEXYZ.Y != 1.0) {
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return (0);
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}
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/*
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* Now convert each XcmsColor structure to CIEXYZ form
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*/
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for (i = 0; i < nColors; i++, pColor++) {
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/* Make sure original format is CIELab */
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if (!XcmsCIELab_ValidSpec(pColor)) {
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return(XcmsFailure);
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}
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/* Calculate Y: assume that Yn = 1.0 */
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tmpL = (pColor->spec.CIELab.L_star + 16.0) / 116.0;
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XYZ_return.Y = tmpL * tmpL * tmpL;
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if (XYZ_return.Y < 0.008856) {
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/* Calculate Y: assume that Yn = 1.0 */
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tmpL = pColor->spec.CIELab.L_star / 9.03292;
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/* Calculate X */
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XYZ_return.X = pLab_WhitePt->spec.CIEXYZ.X *
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((pColor->spec.CIELab.a_star / 3893.5) + tmpL);
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/* Calculate Y */
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XYZ_return.Y = tmpL;
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/* Calculate Z */
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XYZ_return.Z = pLab_WhitePt->spec.CIEXYZ.Z *
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(tmpL - (pColor->spec.CIELab.b_star / 1557.4));
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} else {
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/* Calculate X */
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tmpFloat = tmpL + (pColor->spec.CIELab.a_star / 5.0);
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XYZ_return.X = pLab_WhitePt->spec.CIEXYZ.X * tmpFloat * tmpFloat * tmpFloat;
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/* Calculate Z */
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tmpFloat = tmpL - (pColor->spec.CIELab.b_star / 2.0);
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XYZ_return.Z = pLab_WhitePt->spec.CIEXYZ.Z * tmpFloat * tmpFloat * tmpFloat;
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}
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memcpy((char *)&pColor->spec.CIEXYZ, (char *)&XYZ_return,
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sizeof(XcmsCIEXYZ));
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pColor->format = XcmsCIEXYZFormat;
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}
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return (1);
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}
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/*
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* NAME
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* XcmsCIEXYZToCIELab - convert CIEXYZ to CIELab
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*
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* SYNOPSIS
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*/
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Status
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XcmsCIEXYZToCIELab(
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XcmsCCC ccc,
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XcmsColor *pLab_WhitePt,
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XcmsColor *pColors_in_out,
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unsigned int nColors)
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/*
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* DESCRIPTION
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* Converts color specifications in an array of XcmsColor
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* structures from CIEXYZ format to CIELab format.
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*
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* WARNING: This routine assumes that Yn = 1.0;
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*
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* RETURNS
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* XcmsFailure if failed,
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* XcmsSuccess if succeeded.
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*
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*/
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{
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XcmsCIELab Lab_return;
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XcmsFloat fX_Xn, fY_Yn, fZ_Zn;
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XcmsColor whitePt;
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unsigned int i;
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XcmsColor *pColor = pColors_in_out;
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/*
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* Check arguments
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*/
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if (pLab_WhitePt == NULL || pColors_in_out == NULL) {
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return(XcmsFailure);
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}
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/*
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* Make sure white point is in CIEXYZ form, if not, convert it.
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*/
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if (pLab_WhitePt->format != XcmsCIEXYZFormat) {
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/* Make a copy of the white point because we're going to modify it */
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|
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);
|
|||
|
|
}
|