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RadiancePmap/rgbecontrib.h
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rgbecontrib.h
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/*
=========================================================================
RGBE representation of binned contributions consisting of:
- three 5-bit mantissas for each RGB colour channel
- a common 5-bit exponent
- and a 12-bit bin number for the contribution
= 32 bits.
The floating point RGB contributions are assumed to be SIGNED and
NORMALISED (e.g. divided by their absolute maximum) prior to encoding in
order to maximise the useful range.
Roland Schregle (roland.schregle@{hslu.ch, gmail.com})
(c) Lucerne University of Applied Sciences and Arts,
supported by the Swiss National Science Foundation
(SNSF #179067, "Light Fields for Spatio-Temporal Glare Assessment")
=========================================================================
$Id$
*/
#ifndef _RGBE_CONTRIB_H
#define _RGBE_CONTRIB_H
#include <stdint.h>
/* RGBE Mantissa / exponent / bin bits and their encoding ranges */
#define RGBE_CONTRIB_MANTBITS 5
#define RGBE_CONTRIB_EXPBITS 5
#define RGBE_CONTRIB_BINBITS 12
#define RGBE_CONTRIB_MAXMANT (1 << (RGBE_CONTRIB_MANTBITS - 1))
#define RGBE_CONTRIB_MIN (1.0 / (1L << (1 << RGBE_CONTRIB_EXPBITS)))
#define RGBE_CONTRIB_MAX 1.0
#define RGBE_CONTRIB_MAXBIN ((1L << RGBE_CONTRIB_BINBITS) - 1)
typedef union {
struct {
/* Compressed RGBE representation of binned contributions,
* consisting of a 4-bit mantissa + sign per RGB, a common 5-bit
* exponent, and a 12-bit bin number. */
char red: RGBE_CONTRIB_MANTBITS,
grn: RGBE_CONTRIB_MANTBITS,
blu: RGBE_CONTRIB_MANTBITS,
exp: RGBE_CONTRIB_EXPBITS;
int16_t bin: RGBE_CONTRIB_BINBITS;
};
uint32_t rgbeBin;
} RGBEContrib;
RGBEContrib RGBEContribEnc (double rgb [3], unsigned bin);
/* Encode signed float RGB contributions with associated bin to RGBE */
unsigned RGBEContribDec (RGBEContrib rgbeCont, double rgb [3]);
/* Decode rgbeCont, returning signed floating point contributions in
* array rgb, and the associated bin as return value */
#endif
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