src/common/tonemap.h

/* Copyright (c) 1998 Silicon Graphics, Inc. */

/* SCCSid "$SunId$ SGI" */

/*
 * Header file for tone mapping functions.
 *
 * Include after "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_NOBRT        (-1<<15)        /* bogus brightness value */

#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        hbrmin, hbrmax; /* histogram brightness limits */       
        int             *histo;         /* input histogram */
        TMbright        mbrmin, mbrmax; /* mapped brightness limits */
        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.  This mapping will be used
        in subsequent calls to tmMapPixels() until a new tone mapping
        is computed.  I.e., calls to tmAddHisto() have no immediate effect.

        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, picture 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, picture 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:	3.10
Committed:	Sun Dec 20 16:38:29 1998 UTC (25 years, 4 months ago) by gwlarson
Content type:	text/plain
Branch:	MAIN
Changes since 3.9:	+2 -0 lines
Log Message:	added TM_NOBRT macro for undefined brightnesses
#	User	Rev	Content
1	gwlarson	3.8	/* Copyright (c) 1998 Silicon Graphics, Inc. */
2	greg	3.1
3	gwlarson	3.8	/* SCCSid "$SunId$ SGI" */
4	greg	3.1
5			/*
6			* Header file for tone mapping functions.
7	gwlarson	3.8	*
8			* Include after "color.h"
9	greg	3.1	*/
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	gwlarson	3.8
35	greg	3.1
36			/** Error Return Values **/
37
38			#define TM_E_OK 0 /* normal return status */
39			#define TM_E_NOMEM 1 /* out of memory */
40			#define TM_E_ILLEGAL 2 /* illegal argument value */
41			#define TM_E_TMINVAL 3 /* no valid tone mapping */
42			#define TM_E_TMFAIL 4 /* cannot compute tone mapping */
43			#define TM_E_BADFILE 5 /* cannot open or understand file */
44	greg	3.4	#define TM_E_CODERR1 6 /* code consistency error 1 */
45			#define TM_E_CODERR2 7 /* code consistency error 2 */
46	greg	3.1
47	greg	3.4
48	greg	3.1	/** Conversion Constants and Table Sizes **/
49
50			#define TM_BRTSCALE 128 /* brightness scale factor (integer) */
51
52	gwlarson	3.10	#define TM_NOBRT (-1<<15) /* bogus brightness value */
53
54	greg	3.4	#define TM_MAXPKG 8 /* maximum number of color formats */
55	greg	3.1
56
57	greg	3.4	/** Global Data Types and Structures **/
58
59			#ifndef MEM_PTR
60			#define MEM_PTR void *
61			#endif
62
63	greg	3.1	extern char tmErrorMessage[]; / error messages */
64	gregl	3.6	extern int tmLastError; /* last error incurred by library */
65			extern char tmLastFunction; / error-generating function name */
66	greg	3.1
67			typedef short TMbright; /* encoded luminance type */
68
69			/* basic tone mapping data structure */
70			extern struct tmStruct {
71			int flags; /* flags of what to do */
72			RGBPRIMP monpri; /* monitor RGB primaries */
73			double mongam; /* monitor gamma value (approx.) */
74			COLOR clf; /* computed luminance coefficients */
75	greg	3.4	int cdiv[3]; /* computed color divisors */
76	greg	3.1	RGBPRIMP inppri; /* current input primaries */
77			double inpsf; /* current input scalefactor */
78			COLORMAT cmat; /* color conversion matrix */
79	gregl	3.7	TMbright hbrmin, hbrmax; /* histogram brightness limits */
80	greg	3.1	int histo; / input histogram */
81	gregl	3.7	TMbright mbrmin, mbrmax; /* mapped brightness limits */
82	greg	3.1	unsigned short lumap; / computed luminance map */
83			struct tmStruct tmprev; / previous tone mapping */
84	greg	3.4	MEM_PTR pd[TM_MAXPKG]; /* pointers to private data */
85	greg	3.1	} tmTop; / current tone mapping stack */
86	greg	3.4
87			/* conversion package functions */
88			#ifdef NOPROTO
89			struct tmPackage {
90			MEM_PTR (Init)(); / initialize private data */
91			void (NewSpace)(); / new input color space (optional) */
92			void (Free)(); / free private data */
93			};
94			#else
95			struct tmPackage {
96			MEM_PTR (Init)(struct tmStruct tms);
97			int (NewSpace)(struct tmStruct tms);
98			void (*Free)(MEM_PTR pp);
99			};
100			#endif
101			/* our list of conversion packages */
102			extern struct tmPackage *tmPkg[TM_MAXPKG];
103			extern int tmNumPkgs; /* number of registered packages */
104
105
106	greg	3.1	/** Useful Macros **/
107
108	greg	3.4	/* compute luminance from encoded value */
109	greg	3.1	#define tmLuminance(li) exp((li)/(double)TM_BRTSCALE)
110
111	greg	3.4	/* does tone mapping need color matrix? */
112			#define tmNeedMatrix(t) ((t)->monpri != (t)->inppri)
113
114			/* register a conversion package */
115			#define tmRegPkg(pf) ( tmNumPkgs >= TM_MAXPKG ? -1 : \
116			(tmPkg[tmNumPkgs] = (pf), tmNumPkgs++) )
117
118			/* get the specific package's data */
119			#define tmPkgData(t,i) ((t)->pd[i]!=NULL ? (t)->pd[i] : (*tmPkg[i]->Init)(t))
120
121
122	greg	3.1	/** Library Function Calls **/
123
124	greg	3.4	#ifdef NOPROTO
125	greg	3.1
126	greg	3.3	extern struct tmStruct tmInit(), tmPop(), *tmDup();
127	greg	3.1	extern void tmClearHisto(), tmDone();
128			extern int tmSetSpace(), tmCvColors(), tmCvColrs();
129			extern int tmAddHisto(), tmComputeMapping(), tmMapPixels();
130			extern int tmLoadPicture(), tmMapPicture(), tmPull(), tmPush();
131
132			#else
133
134			extern struct tmStruct *
135			tmInit(int flags, RGBPRIMP monpri, double gamval);
136			/*
137			Initialize new tone mapping and push it onto stack.
138
139			flags - TM_F_* flags indicating what is to be done.
140			monpri - display monitor primaries (Note 1).
141			gamval - display gamma response (can be approximate).
142
143			returns - new tmTop, or NULL if insufficient memory.
144			*/
145
146			extern int
147			tmSetSpace(RGBPRIMP pri, double sf);
148			/*
149			Set color primaries and scale factor for incoming scanlines.
150
151			pri - RGB color input primaries (Note 1).
152			sf - scale factor to get to luminance in cd/m^2.
153
154			returns - 0 on success, TM_E_* code on failure.
155			*/
156
157			extern void
158			tmClearHisto(void);
159			/*
160			Clear histogram for current tone mapping.
161			*/
162
163			extern int
164			tmCvColors(TMbright ls, BYTE cs, COLOR *scan, int len);
165			/*
166			Convert RGB/XYZ float scanline to encoded luminance and chrominance.
167
168			ls - returned encoded luminance values.
169			cs - returned encoded chrominance values (Note 2).
170			scan - input scanline.
171			len - scanline length.
172
173			returns - 0 on success, TM_E_* on error.
174			*/
175
176			extern int
177			tmCvColrs(TMbright ls, BYTE cs, COLR *scan, int len);
178			/*
179			Convert RGBE/XYZE scanline to encoded luminance and chrominance.
180
181			ls - returned encoded luminance values.
182			cs - returned encoded chrominance values (Note 2).
183			scan - input scanline.
184			len - scanline length.
185
186			returns - 0 on success, TM_E_* on error.
187			*/
188
189			extern int
190			tmAddHisto(TMbright *ls, int len, int wt);
191			/*
192			Add brightness values to current histogram.
193
194			ls - encoded luminance values.
195			len - number of luminance values.
196			wt - integer weight to use for each value (usually 1 or -1).
197
198			returns - 0 on success, TM_E_* on error.
199			*/
200
201			extern int
202			tmComputeMapping(double gamval, double Lddyn, double Ldmax);
203			/*
204	gregl	3.7	Compute tone mapping function. This mapping will be used
205			in subsequent calls to tmMapPixels() until a new tone mapping
206			is computed. I.e., calls to tmAddHisto() have no immediate effect.
207	greg	3.1
208			gamval - display gamma response (0. for default).
209			Lddyn - the display's dynamic range (0. for default).
210			Ldmax - maximum display luminance in cd/m^2 (0. for default).
211
212			returns - 0 on success, TM_E_* on failure.
213			*/
214
215			extern int
216			tmMapPixels(BYTE ps, TMbright ls, BYTE *cs, int len);
217			/*
218			Apply tone mapping function to pixel values.
219
220			ps - returned pixel values (Note 2).
221			ls - encoded luminance values.
222			cs - encoded chrominance values (Note 2).
223			len - number of pixels.
224
225			returns - 0 on success, TM_E_* on failure.
226			*/
227
228			extern int
229			tmLoadPicture(TMbright lpp, BYTE cpp, int xp, int yp,
230			char fname, FILE fp);
231			/*
232			Load Radiance picture and convert to tone mapping representation.
233	greg	3.5	Memory for the luminance and chroma arrays is allocated using
234			malloc(3), and should be freed with free(3) when no longer needed.
235	greg	3.3	Calls tmSetSpace() to calibrate input color space.
236	greg	3.1
237	gwlarson	3.9	lpp - returned array of encoded luminances, picture ordering.
238	greg	3.1	cpp - returned array of encoded chrominances (Note 2).
239			xp, yp - returned picture dimensions.
240			fname - picture file name.
241			fp - pointer to open file (Note 3).
242
243			returns - 0 on success, TM_E_* on failure.
244			*/
245
246			extern int
247			tmMapPicture(BYTE *psp, int xp, int *yp, int flags,
248			RGBPRIMP monpri, double gamval, double Lddyn, double Ldmax,
249			char fname, FILE fp);
250			/*
251			Load and apply tone mapping to Radiance picture.
252			Stack is restored to its original state upon return.
253			If fp is TM_GETFILE and (flags&TM_F_UNIMPL)!=0, tmMapPicture()
254			calls pcond to perform the actual conversion, which takes
255			longer but gives access to all the TM_F_* features.
256	greg	3.5	Memory for the final pixel array is allocated using malloc(3),
257			and should be freed with free(3) when it is no longer needed.
258	greg	3.1
259	gwlarson	3.9	psp - returned array of tone mapped pixels, picture ordering.
260	greg	3.1	xp, yp - returned picture dimensions.
261			flags - TM_F_* flags indicating what is to be done.
262			monpri - display monitor primaries (Note 1).
263			gamval - display gamma response.
264			Lddyn - the display's dynamic range (0. for default).
265			Ldmax - maximum display luminance in cd/m^2 (0. for default).
266			fname - picture file name.
267			fp - pointer to open file (Note 3).
268
269			returns - 0 on success, TM_E_* on failure.
270			*/
271
272			extern struct tmStruct *
273			tmPop(void);
274			/*
275			Pops current tone mapping from stack.
276
277			returns - pointer to tone mapping structure, or NULL if none.
278			*/
279
280			extern int
281			tmPull(struct tmStruct *tms);
282			/*
283			Pull tone mapping from anywhere in stack.
284
285			tms - tone mapping structure to find.
286
287			returns - 1 if found in stack, 0 otherwise.
288			*/
289
290			extern int
291			tmPush(struct tmStruct *tms);
292			/*
293			Make tone mapping active by (pulling it and) pushing it to the top.
294
295			tms - initialized tone mapping structure.
296
297			returns - 0 on success, TM_E_* if tms is invalid.
298			*/
299
300	greg	3.3	extern struct tmStruct *
301			tmDup(void);
302			/*
303			Duplicate the current tone mapping into a new structure on the stack.
304
305			returns - pointer to new top, or NULL on error.
306			*/
307
308	greg	3.1	extern void
309			tmDone(struct tmStruct *tms);
310			/*
311			Free data associated with the given tone mapping structure.
312			Calls tmPull() first to remove it from the stack if present.
313			The calls tmDone(tmPop()), tmDone(tmTop) and tmDone(NULL)
314			all have the same effect, which is to remove and free
315			the current tone mapping.
316
317			tms - tone mapping structure to free.
318			*/
319
320			#endif
321	greg	3.4
322
323	greg	3.1	/** Notes **/
324			/*
325			General:
326
327			The usual sequence after calling tmInit() is to convert some
328			pixel values to chroma and luminance encodings, which can
329			be passed to tmAddHisto() to put into the tone mapping histogram.
330			This histogram is then used along with the display parameters
331	greg	3.5	by tmComputeMapping() to compute the luminance mapping function.
332	greg	3.1	(Colors are tone-mapped as they are converted if TM_F_MESOPIC
333			is set.) The encoded chroma and luminance values may then be
334			passed to tmMapPixels() to apply the computed tone mapping in
335			a second pass.
336
337			Especially for RGBE colors in the same color space as the
338			target display, the conversion to chroma and luminance values
339			is fast enough that it may be recomputed on the second pass
340			if memory is at a premium. (Since the chroma values are only
341			used during final mapping, setting the cs parameter to TM_NOCHROM
342			on the first pass will save time.) Another memory saving option
343			if third and subsequent passes are not needed is to use the
344	greg	3.3	same array to store the mapped pixels as used to store
345	greg	3.1	the encoded chroma values. This way, only two extra bytes
346			for storing encoded luminances are required per pixel. This
347			is the method employed by tmMapPicture(), for example.
348			*/
349			/*
350			Note 1:
351
352			All RGBPRIMP values should be pointers to static structures.
353			I.e., the same pointer should be used for the same primaries,
354			and those primaries should not change from one call to the next.
355			This is because the routines use the pointer value to identify
356			computed conversion matrices, so the matrices do not have to be
357			rebuilt each time. If you are using the standard primaries,
358			use the standard primary pointer, stdprims.
359
360			To indicate a set of input primaries are actually CIE XYZ,
361			the TM_XYZPRIM macro may be passed. If the input primaries
362			are unknown, it is wisest to pass tmTop->monpri to tmSetSpace().
363			By default, the input primaries equal the monitor primaries
364			and the scalefactor is set to WHTEFFICACY in tmInit().
365			*/
366			/*
367			Note 2:
368
369			Chrominance is optional in most of these routines, whether
370			TM_F_BW is set or not. Passing a value of TM_NOCHROM (or
371			TM_NOCHROMP for picture reading) indicates that returned
372			color values are not desired.
373
374			If TM_NOCHROM is passed to a mapping routine expecting chroma
375			input, it will do without it and return luminance channel
376			rather than RGB pixel values. Otherwise, the array for
377			returned pixel values may be the same array used to pass
378			encoded chrominances if no other mappings are desired.
379			*/
380			/*
381			Note 3:
382
383			Picture files may either be opened by the calling routine or by
384			the library function. If opened by the calling routine, the
385			pointer to the stream is passed, which may be a pipe or other
386			non-seekable input as it is only read once. It must be
387			positioned at the beginning when the function is called, and it
388			will be positioned at the end on return. It will not be closed.
389			If the passed stream pointer is TM_GETFILE, then the library
390			function will open the file, read its contents and close it
391			before returning, whether or not an error was encountered.
392			*/