1
2/*
3 * Code and supporting documentation (c) Copyright 1990 1991 Tektronix, Inc.
4 * 	All Rights Reserved
5 *
6 * This file is a component of an X Window System-specific implementation
7 * of Xcms based on the TekColor Color Management System.  TekColor is a
8 * trademark of Tektronix, Inc.  The term "TekHVC" designates a particular
9 * color space that is the subject of U.S. Patent No. 4,985,853 (equivalent
10 * foreign patents pending).  Permission is hereby granted to use, copy,
11 * modify, sell, and otherwise distribute this software and its
12 * documentation for any purpose and without fee, provided that:
13 *
14 * 1. This copyright, permission, and disclaimer notice is reproduced in
15 *    all copies of this software and any modification thereof and in
16 *    supporting documentation;
17 * 2. Any color-handling application which displays TekHVC color
18 *    cooordinates identifies these as TekHVC color coordinates in any
19 *    interface that displays these coordinates and in any associated
20 *    documentation;
21 * 3. The term "TekHVC" is always used, and is only used, in association
22 *    with the mathematical derivations of the TekHVC Color Space,
23 *    including those provided in this file and any equivalent pathways and
24 *    mathematical derivations, regardless of digital (e.g., floating point
25 *    or integer) representation.
26 *
27 * Tektronix makes no representation about the suitability of this software
28 * for any purpose.  It is provided "as is" and with all faults.
29 *
30 * TEKTRONIX DISCLAIMS ALL WARRANTIES APPLICABLE TO THIS SOFTWARE,
31 * INCLUDING THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
32 * PARTICULAR PURPOSE.  IN NO EVENT SHALL TEKTRONIX BE LIABLE FOR ANY
33 * SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER
34 * RESULTING FROM LOSS OF USE, DATA, OR PROFITS, WHETHER IN AN ACTION OF
35 * CONTRACT, NEGLIGENCE, OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
36 * CONNECTION WITH THE USE OR THE PERFORMANCE OF THIS SOFTWARE.
37 *
38 *	NAME
39 *		TekHVC.c
40 *
41 *	DESCRIPTION
42 *		This file contains routines that support the TekHVC
43 *		color space to include conversions to and from the CIE
44 *		XYZ space.
45 *
46 *	DOCUMENTATION
47 *		"TekColor Color Management System, System Implementor's Manual"
48 */
49
50#ifdef HAVE_CONFIG_H
51#include <config.h>
52#endif
53#include "Xlibint.h"
54#include "Xcmsint.h"
55#include <X11/Xos.h>
56#include <math.h>
57#include "Cv.h"
58
59#include <stdio.h>
60
61/*
62 *	DEFINES
63 */
64#define u_BR    0.7127          /* u' Best Red */
65#define v_BR    0.4931          /* v' Best Red */
66#define EPS     0.001
67#define CHROMA_SCALE_FACTOR   7.50725
68#ifndef PI
69#  ifdef M_PI
70#    define PI	M_PI
71#  else
72#    define PI       3.14159265358979323846264338327950
73#  endif
74#endif
75#ifndef degrees
76#  define degrees(r) ((XcmsFloat)(r) * 180.0 / PI)
77#endif /* degrees */
78#ifndef radians
79#  define radians(d) ((XcmsFloat)(d) * PI / 180.0)
80#endif /* radians */
81
82/*************************************************************************
83 * Note: The DBL_EPSILON for ANSI is 1e-5 so my checks need to take
84 *       this into account.  If your DBL_EPSILON is different then
85 *       adjust this define.
86 *
87 *       Also note that EPS is the error factor in the calculations
88 *       This may need to be the same as XMY_DBL_EPSILON in
89 *       some implementations.
90 **************************************************************************/
91#ifdef DBL_EPSILON
92#  define XMY_DBL_EPSILON DBL_EPSILON
93#else
94#  define XMY_DBL_EPSILON 0.00001
95#endif
96
97/*
98 *	FORWARD DECLARATIONS
99 */
100static int TekHVC_ParseString(register char *spec, XcmsColor *pColor);
101static Status XcmsTekHVC_ValidSpec(XcmsColor *pColor);
102
103/*
104 *	LOCAL VARIABLES
105 */
106
107    /*
108     * NULL terminated list of functions applied to get from TekHVC to CIEXYZ
109     */
110static XcmsConversionProc Fl_TekHVC_to_CIEXYZ[] = {
111    XcmsTekHVCToCIEuvY,
112    XcmsCIEuvYToCIEXYZ,
113    NULL
114};
115
116    /*
117     * NULL terminated list of functions applied to get from CIEXYZ to TekHVC
118     */
119static XcmsConversionProc Fl_CIEXYZ_to_TekHVC[] = {
120    XcmsCIEXYZToCIEuvY,
121    XcmsCIEuvYToTekHVC,
122    NULL
123};
124
125/*
126 *	GLOBALS
127 */
128
129    /*
130     * TekHVC Color Space
131     */
132XcmsColorSpace	XcmsTekHVCColorSpace =
133    {
134	_XcmsTekHVC_prefix,	/* prefix */
135	XcmsTekHVCFormat,		/* id */
136	TekHVC_ParseString,	/* parseString */
137	Fl_TekHVC_to_CIEXYZ,	/* to_CIEXYZ */
138	Fl_CIEXYZ_to_TekHVC,	/* from_CIEXYZ */
139	1
140    };
141
142
143
144
145/************************************************************************
146 *									*
147 *			 PRIVATE ROUTINES				*
148 *									*
149 ************************************************************************/
150
151/*
152 *	NAME
153 *		TekHVC_ParseString
154 *
155 *	SYNOPSIS
156 */
157static int
158TekHVC_ParseString(
159    register char *spec,
160    XcmsColor *pColor)
161/*
162 *	DESCRIPTION
163 *		This routines takes a string and attempts to convert
164 *		it into a XcmsColor structure with XcmsTekHVCFormat.
165 *		The assumed TekHVC string syntax is:
166 *		    TekHVC:<H>/<V>/<C>
167 *		Where H, V, and C are in string input format for floats
168 *		consisting of:
169 *		    a. an optional sign
170 *		    b. a string of numbers possibly containing a decimal point,
171 *		    c. an optional exponent field containing an 'E' or 'e'
172 *			followed by a possibly signed integer string.
173 *
174 *	RETURNS
175 *		XcmsFailure if invalid;
176 *		XcmsSuccess if valid.
177 */
178{
179    size_t n;
180    char *pchar;
181
182    if ((pchar = strchr(spec, ':')) == NULL) {
183	return(XcmsFailure);
184    }
185    n = (size_t)(pchar - spec);
186
187    /*
188     * Check for proper prefix.
189     */
190    if (strncmp(spec, _XcmsTekHVC_prefix, n) != 0) {
191	return(XcmsFailure);
192    }
193
194    /*
195     * Attempt to parse the value portion.
196     */
197    if (sscanf(spec + n + 1, "%lf/%lf/%lf",
198	    &pColor->spec.TekHVC.H,
199	    &pColor->spec.TekHVC.V,
200	    &pColor->spec.TekHVC.C) != 3) {
201        char *s; /* Maybe failed due to locale */
202        int f;
203        if ((s = strdup(spec))) {
204            for (f = 0; s[f]; ++f)
205                if (s[f] == '.')
206                    s[f] = ',';
207                else if (s[f] == ',')
208                    s[f] = '.';
209	    if (sscanf(s + n + 1, "%lf/%lf/%lf",
210		       &pColor->spec.TekHVC.H,
211		       &pColor->spec.TekHVC.V,
212		       &pColor->spec.TekHVC.C) != 3) {
213                free(s);
214                return(XcmsFailure);
215            }
216            free(s);
217        } else
218	    return(XcmsFailure);
219    }
220    pColor->format = XcmsTekHVCFormat;
221    pColor->pixel = 0;
222    return(XcmsTekHVC_ValidSpec(pColor));
223}
224
225
226/*
227 *	NAME
228 *		ThetaOffset -- compute thetaOffset
229 *
230 *	SYNOPSIS
231 */
232static int
233ThetaOffset(
234    XcmsColor *pWhitePt,
235    XcmsFloat *pThetaOffset)
236/*
237 *	DESCRIPTION
238 *		This routine computes the theta offset of a given
239 *		white point, i.e. XcmsColor.  It is used in both this
240 *		conversion and the printer conversions.
241 *
242 *	RETURNS
243 *		0 if failed.
244 *		1 if succeeded with no modifications.
245 *
246 *	ASSUMPTIONS
247 *		Assumes:
248 *			pWhitePt != NULL
249 *			pWhitePt->format == XcmsCIEuvYFormat
250 *
251 */
252{
253    double div, slopeuv;
254
255    if (pWhitePt == NULL || pWhitePt->format != XcmsCIEuvYFormat) {
256	return(0);
257    }
258
259    if ((div = u_BR - pWhitePt->spec.CIEuvY.u_prime) == 0.0) {
260	return(0);
261    }
262    slopeuv = (v_BR - pWhitePt->spec.CIEuvY.v_prime) / div;
263    *pThetaOffset = degrees(XCMS_ATAN(slopeuv));
264    return(1);
265}
266
267
268
269/************************************************************************
270 *									*
271 *			 PUBLIC ROUTINES				*
272 *									*
273 ************************************************************************/
274
275/*
276 *	NAME
277 *		XcmsTekHVC_ValidSpec()
278 *
279 *	SYNOPSIS
280 */
281static int
282XcmsTekHVC_ValidSpec(
283    XcmsColor *pColor)
284/*
285 *	DESCRIPTION
286 *		Checks if values in the color specification are valid.
287 *		Also brings hue into the range 0.0 <= Hue < 360.0
288 *
289 *	RETURNS
290 *		0 if not valid.
291 *		1 if valid.
292 *
293 */
294{
295    if (pColor->format != XcmsTekHVCFormat) {
296	return(XcmsFailure);
297    }
298    if (pColor->spec.TekHVC.V < (0.0 - XMY_DBL_EPSILON)
299	    || pColor->spec.TekHVC.V > (100.0 + XMY_DBL_EPSILON)
300	    || (pColor->spec.TekHVC.C < 0.0 - XMY_DBL_EPSILON)) {
301	return(XcmsFailure);
302    }
303
304    if (pColor->spec.TekHVC.V < 0.0) {
305	    pColor->spec.TekHVC.V = 0.0 + XMY_DBL_EPSILON;
306    } else if (pColor->spec.TekHVC.V > 100.0) {
307	pColor->spec.TekHVC.V = 100.0 - XMY_DBL_EPSILON;
308    }
309
310    if (pColor->spec.TekHVC.C < 0.0) {
311	pColor->spec.TekHVC.C = 0.0 - XMY_DBL_EPSILON;
312    }
313
314    while (pColor->spec.TekHVC.H < 0.0) {
315	pColor->spec.TekHVC.H += 360.0;
316    }
317    while (pColor->spec.TekHVC.H >= 360.0) {
318	pColor->spec.TekHVC.H -= 360.0;
319    }
320    return(XcmsSuccess);
321}
322
323/*
324 *	NAME
325 *		XcmsTekHVCToCIEuvY - convert TekHVC to CIEuvY
326 *
327 *	SYNOPSIS
328 */
329Status
330XcmsTekHVCToCIEuvY(
331    XcmsCCC ccc,
332    XcmsColor *pHVC_WhitePt,
333    XcmsColor *pColors_in_out,
334    unsigned int nColors)
335/*
336 *	DESCRIPTION
337 *		Transforms an array of TekHVC color specifications, given
338 *		their associated white point, to CIECIEuvY.color
339 *		specifications.
340 *
341 *	RETURNS
342 *		XcmsFailure if failed, XcmsSuccess otherwise.
343 *
344 */
345{
346    XcmsFloat	thetaOffset;
347    XcmsColor	*pColor = pColors_in_out;
348    XcmsColor	whitePt;
349    XcmsCIEuvY	uvY_return;
350    XcmsFloat	tempHue, u, v;
351    XcmsFloat	tmpVal;
352    unsigned int i;
353
354    /*
355     * Check arguments
356     */
357    if (pHVC_WhitePt == NULL || pColors_in_out == NULL) {
358	return(XcmsFailure);
359    }
360
361    /*
362     * Make sure white point is in CIEuvY form
363     */
364    if (pHVC_WhitePt->format != XcmsCIEuvYFormat) {
365	/* Make copy of the white point because we're going to modify it */
366	memcpy((char *)&whitePt, (char *)pHVC_WhitePt, sizeof(XcmsColor));
367	if (!_XcmsDIConvertColors(ccc, &whitePt, (XcmsColor *)NULL, 1,
368		XcmsCIEuvYFormat)) {
369	    return(XcmsFailure);
370	}
371	pHVC_WhitePt = &whitePt;
372    }
373    /* Make sure it is a white point, i.e., Y == 1.0 */
374    if (pHVC_WhitePt->spec.CIEuvY.Y != 1.0) {
375	return(XcmsFailure);
376    }
377
378    /* Get the thetaOffset */
379    if (!ThetaOffset(pHVC_WhitePt, &thetaOffset)) {
380	return(XcmsFailure);
381    }
382
383    /*
384     * Now convert each XcmsColor structure to CIEXYZ form
385     */
386    for (i = 0; i < nColors; i++, pColor++) {
387
388	/* Make sure original format is TekHVC and is valid */
389	if (!XcmsTekHVC_ValidSpec(pColor)) {
390	    return(XcmsFailure);
391	}
392
393	if (pColor->spec.TekHVC.V == 0.0 || pColor->spec.TekHVC.V == 100.0) {
394	    if (pColor->spec.TekHVC.V == 100.0) {
395		uvY_return.Y = 1.0;
396	    } else { /* pColor->spec.TekHVC.V == 0.0 */
397		uvY_return.Y = 0.0;
398	    }
399	    uvY_return.u_prime = pHVC_WhitePt->spec.CIEuvY.u_prime;
400	    uvY_return.v_prime = pHVC_WhitePt->spec.CIEuvY.v_prime;
401	} else {
402
403	    /* Find the hue based on the white point offset */
404	    tempHue = pColor->spec.TekHVC.H + thetaOffset;
405
406	    while (tempHue < 0.0) {
407		tempHue += 360.0;
408	    }
409	    while (tempHue >= 360.0) {
410		tempHue -= 360.0;
411	    }
412
413	    tempHue = radians(tempHue);
414
415	    /* Calculate u'v' for the obtained hue */
416	    u = (XcmsFloat) ((XCMS_COS(tempHue) * pColor->spec.TekHVC.C) /
417		    (pColor->spec.TekHVC.V * (double)CHROMA_SCALE_FACTOR));
418	    v = (XcmsFloat) ((XCMS_SIN(tempHue) * pColor->spec.TekHVC.C) /
419		    (pColor->spec.TekHVC.V * (double)CHROMA_SCALE_FACTOR));
420
421	    /* Based on the white point get the offset from best red */
422	    uvY_return.u_prime = u + pHVC_WhitePt->spec.CIEuvY.u_prime;
423	    uvY_return.v_prime = v + pHVC_WhitePt->spec.CIEuvY.v_prime;
424
425	    /* Calculate the Y value based on the L* = V. */
426	    if (pColor->spec.TekHVC.V < 7.99953624) {
427		uvY_return.Y = pColor->spec.TekHVC.V / 903.29;
428	    } else {
429		tmpVal = (pColor->spec.TekHVC.V + 16.0) / 116.0;
430		uvY_return.Y = tmpVal * tmpVal * tmpVal; /* tmpVal ** 3 */
431	    }
432	}
433
434	/* Copy result to pColor */
435	memcpy((char *)&pColor->spec, (char *)&uvY_return, sizeof(XcmsCIEuvY));
436
437	/* Identify that the format is now CIEuvY */
438	pColor->format = XcmsCIEuvYFormat;
439    }
440    return(XcmsSuccess);
441}
442
443
444/*
445 *	NAME
446 *		XcmsCIEuvYToTekHVC - convert CIEuvY to TekHVC
447 *
448 *	SYNOPSIS
449 */
450Status
451XcmsCIEuvYToTekHVC(
452    XcmsCCC ccc,
453    XcmsColor *pHVC_WhitePt,
454    XcmsColor *pColors_in_out,
455    unsigned int nColors)
456/*
457 *	DESCRIPTION
458 *		Transforms an array of CIECIEuvY.color specifications, given
459 *		their assiciated white point, to TekHVC specifications.
460 *
461 *	RETURNS
462 *		XcmsFailure if failed, XcmsSuccess otherwise.
463 *
464 */
465{
466    XcmsFloat	theta, L2, u, v, nThetaLow, nThetaHigh;
467    XcmsFloat	thetaOffset;
468    XcmsColor	*pColor = pColors_in_out;
469    XcmsColor	whitePt;
470    XcmsTekHVC	HVC_return;
471    unsigned int i;
472
473    /*
474     * Check arguments
475     */
476    if (pHVC_WhitePt == NULL || pColors_in_out == NULL) {
477	return(XcmsFailure);
478    }
479
480    /*
481     * Make sure white point is in CIEuvY form
482     */
483    if (pHVC_WhitePt->format != XcmsCIEuvYFormat) {
484	/* Make copy of the white point because we're going to modify it */
485	memcpy((char *)&whitePt, (char *)pHVC_WhitePt, sizeof(XcmsColor));
486	if (!_XcmsDIConvertColors(ccc, &whitePt, (XcmsColor *)NULL, 1,
487		XcmsCIEuvYFormat)) {
488	    return(XcmsFailure);
489	}
490	pHVC_WhitePt = &whitePt;
491    }
492    /* Make sure it is a white point, i.e., Y == 1.0 */
493    if (pHVC_WhitePt->spec.CIEuvY.Y != 1.0) {
494	return(XcmsFailure);
495    }
496    if (!ThetaOffset(pHVC_WhitePt, &thetaOffset)) {
497	return(XcmsFailure);
498    }
499
500    /*
501     * Now convert each XcmsColor structure to CIEXYZ form
502     */
503    for (i = 0; i < nColors; i++, pColor++) {
504	if (!_XcmsCIEuvY_ValidSpec(pColor)) {
505	    return(XcmsFailure);
506	}
507
508	/* Use the white point offset to determine HVC */
509	u = pColor->spec.CIEuvY.u_prime - pHVC_WhitePt->spec.CIEuvY.u_prime;
510	v = pColor->spec.CIEuvY.v_prime - pHVC_WhitePt->spec.CIEuvY.v_prime;
511
512	/* Calculate the offset */
513	if (u == 0.0) {
514	    theta = 0.0;
515	} else {
516	    theta = v / u;
517	    theta = (XcmsFloat) XCMS_ATAN((double)theta);
518	    theta = degrees(theta);
519	}
520
521	nThetaLow = 0.0;
522	nThetaHigh = 360.0;
523	if (u > 0.0 && v > 0.0) {
524	    nThetaLow = 0.0;
525	    nThetaHigh = 90.0;
526	} else if (u < 0.0 && v > 0.0) {
527	    nThetaLow = 90.0;
528	    nThetaHigh = 180.0;
529	} else if (u < 0.0 && v < 0.0) {
530	    nThetaLow = 180.0;
531	    nThetaHigh = 270.0;
532	} else if (u > 0.0 && v < 0.0) {
533	    nThetaLow = 270.0;
534	    nThetaHigh = 360.0;
535	}
536	while (theta < nThetaLow) {
537		theta += 90.0;
538	}
539	while (theta >= nThetaHigh) {
540	    theta -= 90.0;
541	}
542
543	/* calculate the L value from the given Y */
544	L2 = (pColor->spec.CIEuvY.Y < 0.008856)
545	    ?
546	    (pColor->spec.CIEuvY.Y * 903.29)
547	    :
548	    ((XcmsFloat)(XCMS_CUBEROOT(pColor->spec.CIEuvY.Y) * 116.0) - 16.0);
549	HVC_return.C = L2 * CHROMA_SCALE_FACTOR * XCMS_SQRT((double) ((u * u) + (v * v)));
550	if (HVC_return.C < 0.0) {
551	    theta = 0.0;
552	}
553	HVC_return.V = L2;
554	HVC_return.H = theta - thetaOffset;
555
556	/*
557	 * If this is within the error margin let some other routine later
558	 * in the chain worry about the slop in the calculations.
559	 */
560	while (HVC_return.H < -EPS) {
561	    HVC_return.H += 360.0;
562	}
563	while (HVC_return.H >= 360.0 + EPS) {
564	    HVC_return.H -= 360.0;
565	}
566
567	/* Copy result to pColor */
568	memcpy((char *)&pColor->spec, (char *)&HVC_return, sizeof(XcmsTekHVC));
569
570	/* Identify that the format is now CIEuvY */
571	pColor->format = XcmsTekHVCFormat;
572    }
573    return(XcmsSuccess);
574}
575
576
577/*
578 *	NAME
579 *		_XcmsTekHVC_CheckModify
580 *
581 *	SYNOPSIS
582 */
583int
584_XcmsTekHVC_CheckModify(
585    XcmsColor *pColor)
586/*
587 *	DESCRIPTION
588 *		Checks if values in the color specification are valid.
589 *		If they are not it modifies the values.
590 *		Also brings hue into the range 0.0 <= Hue < 360.0
591 *
592 *	RETURNS
593 *		0 if not valid.
594 *		1 if valid.
595 *
596 */
597{
598    int n;
599
600    /* For now only use the TekHVC numbers as inputs */
601    if (pColor->format != XcmsTekHVCFormat) {
602	return(0);
603    }
604
605    if (pColor->spec.TekHVC.V < 0.0) {
606	pColor->spec.TekHVC.V = 0.0 + XMY_DBL_EPSILON;
607    } else if (pColor->spec.TekHVC.V > 100.0) {
608	pColor->spec.TekHVC.V = 100.0 - XMY_DBL_EPSILON;
609    }
610
611    if (pColor->spec.TekHVC.C < 0.0) {
612	pColor->spec.TekHVC.C = 0.0 - XMY_DBL_EPSILON;
613    }
614
615    if (pColor->spec.TekHVC.H < 0.0) {
616	n = -pColor->spec.TekHVC.H / 360.0;
617	pColor->spec.TekHVC.H += (n + 1) * 360.0;
618	if (pColor->spec.TekHVC.H >= 360.0)
619	    pColor->spec.TekHVC.H -= 360.0;
620    } else if (pColor->spec.TekHVC.H >= 360.0) {
621	n = pColor->spec.TekHVC.H / 360.0;
622	pColor->spec.TekHVC.H -= n * 360.0;
623    }
624    return(1);
625}
626