4.4BSD/usr/src/contrib/X11R5-lib/lib/X/CIELuvMxLC.c
/* $XConsortium: CIELuvMxLC.c,v 1.2 91/07/25 01:07:45 rws 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
* CIELuvMxVC.c
*
* DESCRIPTION
* Source for the XcmsCIELuvQueryMaxLC() 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) (MIN((x), MIN((y), (z))))
#define MAX(x,y) ((x) > (y) ? (x) : (y))
#define MAX3(x,y,z) (MAX((x), MAX((y), (z))))
#define START_LSTAR (XcmsFloat)40.0
#define START_CHROMA (XcmsFloat)2.2
/*
* EXTERNS
*/
extern Status _XcmsConvertColorsWithWhitePt();
/*
* FORWARD DECLARATIONS
*/
Status _XcmsCIELuvQueryMaxLCRGB();
/************************************************************************
* *
* API PRIVATE ROUTINES *
* *
************************************************************************/
/*
* NAME
* _XcmsCIELuvQueryMaxLCRGB - Compute maximum L* and chroma.
*
* SYNOPSIS
*/
Status
_XcmsCIELuvQueryMaxLCRGB(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 angle(radians), 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 as input and outputs
* Luv and RGBi.
*
* RETURNS
* XcmsFailure - Failure
* XcmsSuccess - Succeeded
*
*/
{
XcmsFloat nSmall, nLarge;
XcmsColor tmp;
tmp.format = XcmsCIELuvFormat;
/* Use some unreachable color on the given hue angle */
tmp.spec.CIELuv.L_star = START_LSTAR;
tmp.spec.CIELuv.u_star = XCMS_CIEUSTAROFHUE(hue, START_CHROMA);
tmp.spec.CIELuv.v_star = XCMS_CIEVSTAROFHUE(hue, START_CHROMA);
/*
* Convert from Luv 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 Luv */
if (_XcmsConvertColorsWithWhitePt(ccc, &tmp,
ScreenWhitePointOfCCC(ccc), 1, XcmsCIELuvFormat, (Bool *) NULL)
== XcmsFailure) {
return (XcmsFailure);
}
bcopy((char *)&tmp, (char *)pColor_return, sizeof(XcmsColor));
return (XcmsSuccess);
}
/************************************************************************
* *
* PUBLIC ROUTINES *
* *
************************************************************************/
/*
* NAME
* XcmsCIELuvQueryMaxLC - Compute maximum L* and chroma.
*
* SYNOPSIS
*/
Status
XcmsCIELuvQueryMaxLC (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 */
bcopy ((char *)ccc, (char *)&myCCC, 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(_XcmsCIELuvQueryMaxLCRGB (&myCCC, radians(hue_angle), pColor_return,
(XcmsRGBi *)NULL));
}