src/common/tonemap.h

/* Copyright (c) 1997 Regents of the University of California */

/* SCCSid "$SunId$ LBL" */

/*
 * Header file for tone mapping functions.
 */
                                /* required non-system header files */
#include        "color.h"


/****    Argument Macros    ****/
                                /* Flags of what to do */
#define TM_F_HCONTR     01              /* human contrast sensitivity */
#define TM_F_MESOPIC    02              /* mesopic color sensitivity */
#define TM_F_LINEAR     04              /* linear brightness mapping */
#define TM_F_ACUITY     010             /* acuity adjustment */
#define TM_F_VEIL       020             /* veiling glare */
#define TM_F_CWEIGHT    040             /* center weighting */
#define TM_F_FOVEAL     0100            /* use foveal sample size */
#define TM_F_BW         0200            /* luminance only */
#define TM_F_NOSTDERR   0400            /* don't report errors to stderr */
                                /* combined modes */
#define TM_F_CAMERA     0
#define TM_F_HUMAN      (TM_F_HCONTR|TM_F_MESOPIC|TM_F_VEIL|\
                                TM_F_ACUITY|TM_F_FOVEAL)
#define TM_F_UNIMPL     (TM_F_CWEIGHT|TM_F_VEIL|TM_F_ACUITY|TM_F_FOVEAL)

                                /* special pointer values */
#define TM_XYZPRIM      (RGBPRIMP)NULL  /* indicate XYZ primaries (Note 1) */
#define TM_NOCHROM      (BYTE *)NULL    /* indicate no chrominance */
#define TM_NOCHROMP     (BYTE **)NULL   /* indicate no chrominances */
#define TM_GETFILE      (FILE *)NULL    /* indicate file must be opened */

/****    Error Return Values    ****/

#define TM_E_OK         0               /* normal return status */
#define TM_E_NOMEM      1               /* out of memory */
#define TM_E_ILLEGAL    2               /* illegal argument value */
#define TM_E_TMINVAL    3               /* no valid tone mapping */
#define TM_E_TMFAIL     4               /* cannot compute tone mapping */
#define TM_E_BADFILE    5               /* cannot open or understand file */
#define TM_E_CODERR1    6               /* code consistency error 1 */
#define TM_E_CODERR2    7               /* code consistency error 2 */


/****    Conversion Constants and Table Sizes    ****/

#define TM_BRTSCALE     128             /* brightness scale factor (integer) */

#define TM_MAXPKG       8               /* maximum number of color formats */


/****    Global Data Types and Structures    ****/

#ifndef MEM_PTR
#define MEM_PTR         void *
#endif

extern char     *tmErrorMessage[];      /* error messages */
extern int      tmLastError;            /* last error incurred by library */
extern char     *tmLastFunction;        /* error-generating function name */

typedef short   TMbright;               /* encoded luminance type */

                                /* basic tone mapping data structure */
extern struct tmStruct {
        int             flags;          /* flags of what to do */
        RGBPRIMP        monpri;         /* monitor RGB primaries */
        double          mongam;         /* monitor gamma value (approx.) */
        COLOR           clf;            /* computed luminance coefficients */
        int             cdiv[3];        /* computed color divisors */
        RGBPRIMP        inppri;         /* current input primaries */
        double          inpsf;          /* current input scalefactor */
        COLORMAT        cmat;           /* color conversion matrix */
        TMbright        brmin, brmax;   /* input brightness limits */   
        int             *histo;         /* input histogram */
        unsigned short  *lumap;         /* computed luminance map */
        struct tmStruct *tmprev;        /* previous tone mapping */
        MEM_PTR         pd[TM_MAXPKG];  /* pointers to private data */
}       *tmTop;                 /* current tone mapping stack */

                                /* conversion package functions */
#ifdef  NOPROTO
struct tmPackage {
        MEM_PTR         (*Init)();      /* initialize private data */
        void            (*NewSpace)();  /* new input color space (optional) */
        void            (*Free)();      /* free private data */
};
#else
struct tmPackage {
        MEM_PTR         (*Init)(struct tmStruct *tms);
        int             (*NewSpace)(struct tmStruct *tms);
        void            (*Free)(MEM_PTR pp);
};
#endif
                                /* our list of conversion packages */
extern struct tmPackage *tmPkg[TM_MAXPKG];
extern int      tmNumPkgs;      /* number of registered packages */


/****    Useful Macros    ****/

                                /* compute luminance from encoded value */
#define tmLuminance(li) exp((li)/(double)TM_BRTSCALE)

                                /* does tone mapping need color matrix? */
#define tmNeedMatrix(t) ((t)->monpri != (t)->inppri)

                                /* register a conversion package */
#define tmRegPkg(pf)    ( tmNumPkgs >= TM_MAXPKG ? -1 : \
                                (tmPkg[tmNumPkgs] = (pf), tmNumPkgs++) )

                                /* get the specific package's data */
#define tmPkgData(t,i)  ((t)->pd[i]!=NULL ? (t)->pd[i] : (*tmPkg[i]->Init)(t))


/****    Library Function Calls    ****/

#ifdef  NOPROTO

extern struct tmStruct  *tmInit(), *tmPop(), *tmDup();
extern void     tmClearHisto(), tmDone();
extern int      tmSetSpace(), tmCvColors(), tmCvColrs();
extern int      tmAddHisto(), tmComputeMapping(), tmMapPixels();
extern int      tmLoadPicture(), tmMapPicture(), tmPull(), tmPush();

#else

extern struct tmStruct *
tmInit(int flags, RGBPRIMP monpri, double gamval);
/*
        Initialize new tone mapping and push it onto stack.

        flags   -       TM_F_* flags indicating what is to be done.
        monpri  -       display monitor primaries (Note 1).
        gamval  -       display gamma response (can be approximate).

        returns -       new tmTop, or NULL if insufficient memory.
*/

extern int
tmSetSpace(RGBPRIMP pri, double sf);
/*
        Set color primaries and scale factor for incoming scanlines.

        pri     -       RGB color input primaries (Note 1).
        sf      -       scale factor to get to luminance in cd/m^2.

        returns -       0 on success, TM_E_* code on failure.
*/

extern void
tmClearHisto(void);
/*
        Clear histogram for current tone mapping.
*/

extern int
tmCvColors(TMbright *ls, BYTE *cs, COLOR *scan, int len);
/*
        Convert RGB/XYZ float scanline to encoded luminance and chrominance.

        ls      -       returned encoded luminance values.
        cs      -       returned encoded chrominance values (Note 2).
        scan    -       input scanline.
        len     -       scanline length.

        returns -       0 on success, TM_E_* on error.
*/

extern int
tmCvColrs(TMbright *ls, BYTE *cs, COLR *scan, int len);
/*
        Convert RGBE/XYZE scanline to encoded luminance and chrominance.

        ls      -       returned encoded luminance values.
        cs      -       returned encoded chrominance values (Note 2).
        scan    -       input scanline.
        len     -       scanline length.

        returns -       0 on success, TM_E_* on error.
*/

extern int
tmAddHisto(TMbright *ls, int len, int wt);
/*
        Add brightness values to current histogram.

        ls      -       encoded luminance values.
        len     -       number of luminance values.
        wt      -       integer weight to use for each value (usually 1 or -1).

        returns -       0 on success, TM_E_* on error.
*/

extern int
tmComputeMapping(double gamval, double Lddyn, double Ldmax);
/*
        Compute tone mapping function.

        gamval  -       display gamma response (0. for default).
        Lddyn   -       the display's dynamic range (0. for default).
        Ldmax   -       maximum display luminance in cd/m^2 (0. for default).

        returns -       0 on success, TM_E_* on failure.
*/

extern int
tmMapPixels(BYTE *ps, TMbright *ls, BYTE *cs, int len);
/*
        Apply tone mapping function to pixel values.

        ps      -       returned pixel values (Note 2).
        ls      -       encoded luminance values.
        cs      -       encoded chrominance values (Note 2).
        len     -       number of pixels.

        returns -       0 on success, TM_E_* on failure.
*/

extern int
tmLoadPicture(TMbright **lpp, BYTE **cpp, int *xp, int *yp,
                char *fname, FILE *fp);
/*
        Load Radiance picture and convert to tone mapping representation.
        Memory for the luminance and chroma arrays is allocated using
        malloc(3), and should be freed with free(3) when no longer needed.
        Calls tmSetSpace() to calibrate input color space.

        lpp     -       returned array of encoded luminances, English ordering.
        cpp     -       returned array of encoded chrominances (Note 2).
        xp, yp  -       returned picture dimensions.
        fname   -       picture file name.
        fp      -       pointer to open file (Note 3).

        returns -       0 on success, TM_E_* on failure.
*/

extern int
tmMapPicture(BYTE **psp, int *xp, int *yp, int flags,
                RGBPRIMP monpri, double gamval, double Lddyn, double Ldmax,
                char *fname, FILE *fp);
/*
        Load and apply tone mapping to Radiance picture.
        Stack is restored to its original state upon return.
        If fp is TM_GETFILE and (flags&TM_F_UNIMPL)!=0, tmMapPicture()
        calls pcond to perform the actual conversion, which takes
        longer but gives access to all the TM_F_* features.
        Memory for the final pixel array is allocated using malloc(3),
        and should be freed with free(3) when it is no longer needed.

        psp     -       returned array of tone mapped pixels, English ordering.
        xp, yp  -       returned picture dimensions.
        flags   -       TM_F_* flags indicating what is to be done.
        monpri  -       display monitor primaries (Note 1).
        gamval  -       display gamma response.
        Lddyn   -       the display's dynamic range (0. for default).
        Ldmax   -       maximum display luminance in cd/m^2 (0. for default).
        fname   -       picture file name.
        fp      -       pointer to open file (Note 3).

        returns -       0 on success, TM_E_* on failure.
*/

extern struct tmStruct *
tmPop(void);
/*
        Pops current tone mapping from stack.

        returns -       pointer to tone mapping structure, or NULL if none.
*/

extern int
tmPull(struct tmStruct *tms);
/*
        Pull tone mapping from anywhere in stack.

        tms     -       tone mapping structure to find.

        returns -       1 if found in stack, 0 otherwise.
*/

extern int
tmPush(struct tmStruct *tms);
/*
        Make tone mapping active by (pulling it and) pushing it to the top.

        tms     -       initialized tone mapping structure.

        returns -       0 on success, TM_E_* if tms is invalid.
*/

extern struct tmStruct *
tmDup(void);
/*
        Duplicate the current tone mapping into a new structure on the stack.

        returns -       pointer to new top, or NULL on error.
*/

extern void
tmDone(struct tmStruct *tms);
/*
        Free data associated with the given tone mapping structure.
        Calls tmPull() first to remove it from the stack if present.
        The calls tmDone(tmPop()), tmDone(tmTop) and tmDone(NULL)
        all have the same effect, which is to remove and free
        the current tone mapping.

        tms     -       tone mapping structure to free.
*/

#endif


/****    Notes    ****/
/*
        General:

        The usual sequence after calling tmInit() is to convert some
        pixel values to chroma and luminance encodings, which can
        be passed to tmAddHisto() to put into the tone mapping histogram.
        This histogram is then used along with the display parameters
        by tmComputeMapping() to compute the luminance mapping function.
        (Colors are tone-mapped as they are converted if TM_F_MESOPIC
        is set.)  The encoded chroma and luminance values may then be
        passed to tmMapPixels() to apply the computed tone mapping in
        a second pass.

        Especially for RGBE colors in the same color space as the
        target display, the conversion to chroma and luminance values
        is fast enough that it may be recomputed on the second pass
        if memory is at a premium.  (Since the chroma values are only
        used during final mapping, setting the cs parameter to TM_NOCHROM
        on the first pass will save time.)  Another memory saving option
        if third and subsequent passes are not needed is to use the
        same array to store the mapped pixels as used to store
        the encoded chroma values.  This way, only two extra bytes
        for storing encoded luminances are required per pixel.  This
        is the method employed by tmMapPicture(), for example.
*/
/*
        Note 1:

        All RGBPRIMP values should be pointers to static structures.
        I.e., the same pointer should be used for the same primaries,
        and those primaries should not change from one call to the next.
        This is because the routines use the pointer value to identify
        computed conversion matrices, so the matrices do not have to be
        rebuilt each time.  If you are using the standard primaries,
        use the standard primary pointer, stdprims.

        To indicate a set of input primaries are actually CIE XYZ,
        the TM_XYZPRIM macro may be passed.  If the input primaries
        are unknown, it is wisest to pass tmTop->monpri to tmSetSpace().
        By default, the input primaries equal the monitor primaries
        and the scalefactor is set to WHTEFFICACY in tmInit().
*/
/*
        Note 2:

        Chrominance is optional in most of these routines, whether
        TM_F_BW is set or not.  Passing a value of TM_NOCHROM (or
        TM_NOCHROMP for picture reading) indicates that returned
        color values are not desired.
        
        If TM_NOCHROM is passed to a mapping routine expecting chroma
        input, it will do without it and return luminance channel
        rather than RGB pixel values.  Otherwise, the array for
        returned pixel values may be the same array used to pass
        encoded chrominances if no other mappings are desired.
*/
/*
        Note 3:

        Picture files may either be opened by the calling routine or by
        the library function.  If opened by the calling routine, the
        pointer to the stream is passed, which may be a pipe or other
        non-seekable input as it is only read once.  It must be
        positioned at the beginning when the function is called, and it
        will be positioned at the end on return.  It will not be closed.
        If the passed stream pointer is TM_GETFILE, then the library
        function will open the file, read its contents and close it
        before returning, whether or not an error was encountered.
*/
Revision:	3.6
Committed:	Tue Jul 29 11:54:45 1997 UTC (26 years, 9 months ago) by gregl
Content type:	text/plain
Branch:	MAIN
Changes since 3.5:	+2 -0 lines
Log Message:	added tmLastError and tmLastFunction globals (set by tmErrorReturn)
#	User	Rev	Content
1	greg	3.1	/* Copyright (c) 1997 Regents of the University of California */
2
3			/* SCCSid "$SunId$ LBL" */
4
5			/*
6			* Header file for tone mapping functions.
7			*/
8			/* required non-system header files */
9			#include "color.h"
10
11	greg	3.4
12	greg	3.1	/** Argument Macros **/
13			/* Flags of what to do */
14			#define TM_F_HCONTR 01 /* human contrast sensitivity */
15			#define TM_F_MESOPIC 02 /* mesopic color sensitivity */
16			#define TM_F_LINEAR 04 /* linear brightness mapping */
17			#define TM_F_ACUITY 010 /* acuity adjustment */
18			#define TM_F_VEIL 020 /* veiling glare */
19			#define TM_F_CWEIGHT 040 /* center weighting */
20			#define TM_F_FOVEAL 0100 /* use foveal sample size */
21			#define TM_F_BW 0200 /* luminance only */
22	greg	3.2	#define TM_F_NOSTDERR 0400 /* don't report errors to stderr */
23	greg	3.1	/* combined modes */
24			#define TM_F_CAMERA 0
25			#define TM_F_HUMAN (TM_F_HCONTR\|TM_F_MESOPIC\|TM_F_VEIL\|\
26			TM_F_ACUITY\|TM_F_FOVEAL)
27			#define TM_F_UNIMPL (TM_F_CWEIGHT\|TM_F_VEIL\|TM_F_ACUITY\|TM_F_FOVEAL)
28
29			/* special pointer values */
30			#define TM_XYZPRIM (RGBPRIMP)NULL /* indicate XYZ primaries (Note 1) */
31			#define TM_NOCHROM (BYTE )NULL / indicate no chrominance */
32			#define TM_NOCHROMP (BYTE *)NULL / indicate no chrominances */
33			#define TM_GETFILE (FILE )NULL / indicate file must be opened */
34
35			/** Error Return Values **/
36
37			#define TM_E_OK 0 /* normal return status */
38			#define TM_E_NOMEM 1 /* out of memory */
39			#define TM_E_ILLEGAL 2 /* illegal argument value */
40			#define TM_E_TMINVAL 3 /* no valid tone mapping */
41			#define TM_E_TMFAIL 4 /* cannot compute tone mapping */
42			#define TM_E_BADFILE 5 /* cannot open or understand file */
43	greg	3.4	#define TM_E_CODERR1 6 /* code consistency error 1 */
44			#define TM_E_CODERR2 7 /* code consistency error 2 */
45	greg	3.1
46	greg	3.4
47	greg	3.1	/** Conversion Constants and Table Sizes **/
48
49			#define TM_BRTSCALE 128 /* brightness scale factor (integer) */
50
51	greg	3.4	#define TM_MAXPKG 8 /* maximum number of color formats */
52	greg	3.1
53
54	greg	3.4	/** Global Data Types and Structures **/
55
56			#ifndef MEM_PTR
57			#define MEM_PTR void *
58			#endif
59
60	greg	3.1	extern char tmErrorMessage[]; / error messages */
61	gregl	3.6	extern int tmLastError; /* last error incurred by library */
62			extern char tmLastFunction; / error-generating function name */
63	greg	3.1
64			typedef short TMbright; /* encoded luminance type */
65
66			/* basic tone mapping data structure */
67			extern struct tmStruct {
68			int flags; /* flags of what to do */
69			RGBPRIMP monpri; /* monitor RGB primaries */
70			double mongam; /* monitor gamma value (approx.) */
71			COLOR clf; /* computed luminance coefficients */
72	greg	3.4	int cdiv[3]; /* computed color divisors */
73	greg	3.1	RGBPRIMP inppri; /* current input primaries */
74			double inpsf; /* current input scalefactor */
75			COLORMAT cmat; /* color conversion matrix */
76			TMbright brmin, brmax; /* input brightness limits */
77			int histo; / input histogram */
78			unsigned short lumap; / computed luminance map */
79			struct tmStruct tmprev; / previous tone mapping */
80	greg	3.4	MEM_PTR pd[TM_MAXPKG]; /* pointers to private data */
81	greg	3.1	} tmTop; / current tone mapping stack */
82	greg	3.4
83			/* conversion package functions */
84			#ifdef NOPROTO
85			struct tmPackage {
86			MEM_PTR (Init)(); / initialize private data */
87			void (NewSpace)(); / new input color space (optional) */
88			void (Free)(); / free private data */
89			};
90			#else
91			struct tmPackage {
92			MEM_PTR (Init)(struct tmStruct tms);
93			int (NewSpace)(struct tmStruct tms);
94			void (*Free)(MEM_PTR pp);
95			};
96			#endif
97			/* our list of conversion packages */
98			extern struct tmPackage *tmPkg[TM_MAXPKG];
99			extern int tmNumPkgs; /* number of registered packages */
100
101
102	greg	3.1	/** Useful Macros **/
103
104	greg	3.4	/* compute luminance from encoded value */
105	greg	3.1	#define tmLuminance(li) exp((li)/(double)TM_BRTSCALE)
106
107	greg	3.4	/* does tone mapping need color matrix? */
108			#define tmNeedMatrix(t) ((t)->monpri != (t)->inppri)
109
110			/* register a conversion package */
111			#define tmRegPkg(pf) ( tmNumPkgs >= TM_MAXPKG ? -1 : \
112			(tmPkg[tmNumPkgs] = (pf), tmNumPkgs++) )
113
114			/* get the specific package's data */
115			#define tmPkgData(t,i) ((t)->pd[i]!=NULL ? (t)->pd[i] : (*tmPkg[i]->Init)(t))
116
117
118	greg	3.1	/** Library Function Calls **/
119
120	greg	3.4	#ifdef NOPROTO
121	greg	3.1
122	greg	3.3	extern struct tmStruct tmInit(), tmPop(), *tmDup();
123	greg	3.1	extern void tmClearHisto(), tmDone();
124			extern int tmSetSpace(), tmCvColors(), tmCvColrs();
125			extern int tmAddHisto(), tmComputeMapping(), tmMapPixels();
126			extern int tmLoadPicture(), tmMapPicture(), tmPull(), tmPush();
127
128			#else
129
130			extern struct tmStruct *
131			tmInit(int flags, RGBPRIMP monpri, double gamval);
132			/*
133			Initialize new tone mapping and push it onto stack.
134
135			flags - TM_F_* flags indicating what is to be done.
136			monpri - display monitor primaries (Note 1).
137			gamval - display gamma response (can be approximate).
138
139			returns - new tmTop, or NULL if insufficient memory.
140			*/
141
142			extern int
143			tmSetSpace(RGBPRIMP pri, double sf);
144			/*
145			Set color primaries and scale factor for incoming scanlines.
146
147			pri - RGB color input primaries (Note 1).
148			sf - scale factor to get to luminance in cd/m^2.
149
150			returns - 0 on success, TM_E_* code on failure.
151			*/
152
153			extern void
154			tmClearHisto(void);
155			/*
156			Clear histogram for current tone mapping.
157			*/
158
159			extern int
160			tmCvColors(TMbright ls, BYTE cs, COLOR *scan, int len);
161			/*
162			Convert RGB/XYZ float scanline to encoded luminance and chrominance.
163
164			ls - returned encoded luminance values.
165			cs - returned encoded chrominance values (Note 2).
166			scan - input scanline.
167			len - scanline length.
168
169			returns - 0 on success, TM_E_* on error.
170			*/
171
172			extern int
173			tmCvColrs(TMbright ls, BYTE cs, COLR *scan, int len);
174			/*
175			Convert RGBE/XYZE scanline to encoded luminance and chrominance.
176
177			ls - returned encoded luminance values.
178			cs - returned encoded chrominance values (Note 2).
179			scan - input scanline.
180			len - scanline length.
181
182			returns - 0 on success, TM_E_* on error.
183			*/
184
185			extern int
186			tmAddHisto(TMbright *ls, int len, int wt);
187			/*
188			Add brightness values to current histogram.
189
190			ls - encoded luminance values.
191			len - number of luminance values.
192			wt - integer weight to use for each value (usually 1 or -1).
193
194			returns - 0 on success, TM_E_* on error.
195			*/
196
197			extern int
198			tmComputeMapping(double gamval, double Lddyn, double Ldmax);
199			/*
200			Compute tone mapping function.
201
202			gamval - display gamma response (0. for default).
203			Lddyn - the display's dynamic range (0. for default).
204			Ldmax - maximum display luminance in cd/m^2 (0. for default).
205
206			returns - 0 on success, TM_E_* on failure.
207			*/
208
209			extern int
210			tmMapPixels(BYTE ps, TMbright ls, BYTE *cs, int len);
211			/*
212			Apply tone mapping function to pixel values.
213
214			ps - returned pixel values (Note 2).
215			ls - encoded luminance values.
216			cs - encoded chrominance values (Note 2).
217			len - number of pixels.
218
219			returns - 0 on success, TM_E_* on failure.
220			*/
221
222			extern int
223			tmLoadPicture(TMbright lpp, BYTE cpp, int xp, int yp,
224			char fname, FILE fp);
225			/*
226			Load Radiance picture and convert to tone mapping representation.
227	greg	3.5	Memory for the luminance and chroma arrays is allocated using
228			malloc(3), and should be freed with free(3) when no longer needed.
229	greg	3.3	Calls tmSetSpace() to calibrate input color space.
230	greg	3.1
231			lpp - returned array of encoded luminances, English ordering.
232			cpp - returned array of encoded chrominances (Note 2).
233			xp, yp - returned picture dimensions.
234			fname - picture file name.
235			fp - pointer to open file (Note 3).
236
237			returns - 0 on success, TM_E_* on failure.
238			*/
239
240			extern int
241			tmMapPicture(BYTE *psp, int xp, int *yp, int flags,
242			RGBPRIMP monpri, double gamval, double Lddyn, double Ldmax,
243			char fname, FILE fp);
244			/*
245			Load and apply tone mapping to Radiance picture.
246			Stack is restored to its original state upon return.
247			If fp is TM_GETFILE and (flags&TM_F_UNIMPL)!=0, tmMapPicture()
248			calls pcond to perform the actual conversion, which takes
249			longer but gives access to all the TM_F_* features.
250	greg	3.5	Memory for the final pixel array is allocated using malloc(3),
251			and should be freed with free(3) when it is no longer needed.
252	greg	3.1
253			psp - returned array of tone mapped pixels, English ordering.
254			xp, yp - returned picture dimensions.
255			flags - TM_F_* flags indicating what is to be done.
256			monpri - display monitor primaries (Note 1).
257			gamval - display gamma response.
258			Lddyn - the display's dynamic range (0. for default).
259			Ldmax - maximum display luminance in cd/m^2 (0. for default).
260			fname - picture file name.
261			fp - pointer to open file (Note 3).
262
263			returns - 0 on success, TM_E_* on failure.
264			*/
265
266			extern struct tmStruct *
267			tmPop(void);
268			/*
269			Pops current tone mapping from stack.
270
271			returns - pointer to tone mapping structure, or NULL if none.
272			*/
273
274			extern int
275			tmPull(struct tmStruct *tms);
276			/*
277			Pull tone mapping from anywhere in stack.
278
279			tms - tone mapping structure to find.
280
281			returns - 1 if found in stack, 0 otherwise.
282			*/
283
284			extern int
285			tmPush(struct tmStruct *tms);
286			/*
287			Make tone mapping active by (pulling it and) pushing it to the top.
288
289			tms - initialized tone mapping structure.
290
291			returns - 0 on success, TM_E_* if tms is invalid.
292			*/
293
294	greg	3.3	extern struct tmStruct *
295			tmDup(void);
296			/*
297			Duplicate the current tone mapping into a new structure on the stack.
298
299			returns - pointer to new top, or NULL on error.
300			*/
301
302	greg	3.1	extern void
303			tmDone(struct tmStruct *tms);
304			/*
305			Free data associated with the given tone mapping structure.
306			Calls tmPull() first to remove it from the stack if present.
307			The calls tmDone(tmPop()), tmDone(tmTop) and tmDone(NULL)
308			all have the same effect, which is to remove and free
309			the current tone mapping.
310
311			tms - tone mapping structure to free.
312			*/
313
314			#endif
315	greg	3.4
316
317	greg	3.1	/** Notes **/
318			/*
319			General:
320
321			The usual sequence after calling tmInit() is to convert some
322			pixel values to chroma and luminance encodings, which can
323			be passed to tmAddHisto() to put into the tone mapping histogram.
324			This histogram is then used along with the display parameters
325	greg	3.5	by tmComputeMapping() to compute the luminance mapping function.
326	greg	3.1	(Colors are tone-mapped as they are converted if TM_F_MESOPIC
327			is set.) The encoded chroma and luminance values may then be
328			passed to tmMapPixels() to apply the computed tone mapping in
329			a second pass.
330
331			Especially for RGBE colors in the same color space as the
332			target display, the conversion to chroma and luminance values
333			is fast enough that it may be recomputed on the second pass
334			if memory is at a premium. (Since the chroma values are only
335			used during final mapping, setting the cs parameter to TM_NOCHROM
336			on the first pass will save time.) Another memory saving option
337			if third and subsequent passes are not needed is to use the
338	greg	3.3	same array to store the mapped pixels as used to store
339	greg	3.1	the encoded chroma values. This way, only two extra bytes
340			for storing encoded luminances are required per pixel. This
341			is the method employed by tmMapPicture(), for example.
342			*/
343			/*
344			Note 1:
345
346			All RGBPRIMP values should be pointers to static structures.
347			I.e., the same pointer should be used for the same primaries,
348			and those primaries should not change from one call to the next.
349			This is because the routines use the pointer value to identify
350			computed conversion matrices, so the matrices do not have to be
351			rebuilt each time. If you are using the standard primaries,
352			use the standard primary pointer, stdprims.
353
354			To indicate a set of input primaries are actually CIE XYZ,
355			the TM_XYZPRIM macro may be passed. If the input primaries
356			are unknown, it is wisest to pass tmTop->monpri to tmSetSpace().
357			By default, the input primaries equal the monitor primaries
358			and the scalefactor is set to WHTEFFICACY in tmInit().
359			*/
360			/*
361			Note 2:
362
363			Chrominance is optional in most of these routines, whether
364			TM_F_BW is set or not. Passing a value of TM_NOCHROM (or
365			TM_NOCHROMP for picture reading) indicates that returned
366			color values are not desired.
367
368			If TM_NOCHROM is passed to a mapping routine expecting chroma
369			input, it will do without it and return luminance channel
370			rather than RGB pixel values. Otherwise, the array for
371			returned pixel values may be the same array used to pass
372			encoded chrominances if no other mappings are desired.
373			*/
374			/*
375			Note 3:
376
377			Picture files may either be opened by the calling routine or by
378			the library function. If opened by the calling routine, the
379			pointer to the stream is passed, which may be a pipe or other
380			non-seekable input as it is only read once. It must be
381			positioned at the beginning when the function is called, and it
382			will be positioned at the end on return. It will not be closed.
383			If the passed stream pointer is TM_GETFILE, then the library
384			function will open the file, read its contents and close it
385			before returning, whether or not an error was encountered.
386			*/