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tif_luv.c
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tif_luv.c
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/* $Id$ */
/*
* Copyright (c) 1997 Greg Ward Larson
* Copyright (c) 1997 Silicon Graphics, Inc.
*
* Permission to use, copy, modify, distribute, and sell this software and
* its documentation for any purpose is hereby granted without fee, provided
* that (i) the above copyright notices and this permission notice appear in
* all copies of the software and related documentation, and (ii) the names of
* Sam Leffler, Greg Larson and Silicon Graphics may not be used in any
* advertising or publicity relating to the software without the specific,
* prior written permission of Sam Leffler, Greg Larson and Silicon Graphics.
*
* THE SOFTWARE IS PROVIDED "AS-IS" AND WITHOUT WARRANTY OF ANY KIND,
* EXPRESS, IMPLIED OR OTHERWISE, INCLUDING WITHOUT LIMITATION, ANY
* WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
*
* IN NO EVENT SHALL SAM LEFFLER, GREG LARSON OR SILICON GRAPHICS BE LIABLE
* FOR ANY SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY KIND,
* OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
* WHETHER OR NOT ADVISED OF THE POSSIBILITY OF DAMAGE, AND ON ANY THEORY OF
* LIABILITY, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
* OF THIS SOFTWARE.
*/
#include "tiffiop.h"
#ifdef LOGLUV_SUPPORT
/*
* TIFF Library.
* LogLuv compression support for high dynamic range images.
*
* Contributed by Greg Larson.
*
* LogLuv image support uses the TIFF library to store 16 or 10-bit
* log luminance values with 8 bits each of u and v or a 14-bit index.
*
* The codec can take as input and produce as output 32-bit IEEE float values
* as well as 16-bit integer values. A 16-bit luminance is interpreted
* as a sign bit followed by a 15-bit integer that is converted
* to and from a linear magnitude using the transformation:
*
* L = 2^( (Le+.5)/256 - 64 ) # real from 15-bit
*
* Le = floor( 256*(log2(L) + 64) ) # 15-bit from real
*
* The actual conversion to world luminance units in candelas per sq. meter
* requires an additional multiplier, which is stored in the TIFFTAG_STONITS.
* This value is usually set such that a reasonable exposure comes from
* clamping decoded luminances above 1 to 1 in the displayed image.
*
* The 16-bit values for u and v may be converted to real values by dividing
* each by 32768. (This allows for negative values, which aren't useful as
* far as we know, but are left in case of future improvements in human
* color vision.)
*
* Conversion from (u,v), which is actually the CIE (u',v') system for
* you color scientists, is accomplished by the following transformation:
*
* u = 4*x / (-2*x + 12*y + 3)
* v = 9*y / (-2*x + 12*y + 3)
*
* x = 9*u / (6*u - 16*v + 12)
* y = 4*v / (6*u - 16*v + 12)
*
* This process is greatly simplified by passing 32-bit IEEE floats
* for each of three CIE XYZ coordinates. The codec then takes care
* of conversion to and from LogLuv, though the application is still
* responsible for interpreting the TIFFTAG_STONITS calibration factor.
*
* By definition, a CIE XYZ vector of [1 1 1] corresponds to a neutral white
* point of (x,y)=(1/3,1/3). However, most color systems assume some other
* white point, such as D65, and an absolute color conversion to XYZ then
* to another color space with a different white point may introduce an
* unwanted color cast to the image. It is often desirable, therefore, to
* perform a white point conversion that maps the input white to [1 1 1]
* in XYZ, then record the original white point using the TIFFTAG_WHITEPOINT
* tag value. A decoder that demands absolute color calibration may use
* this white point tag to get back the original colors, but usually it
* will be ignored and the new white point will be used instead that
* matches the output color space.
*
* Pixel information is compressed into one of two basic encodings, depending
* on the setting of the compression tag, which is one of COMPRESSION_SGILOG
* or COMPRESSION_SGILOG24. For COMPRESSION_SGILOG, greyscale data is
* stored as:
*
* 1 15
* |-+---------------|
*
* COMPRESSION_SGILOG color data is stored as:
*
* 1 15 8 8
* |-+---------------|--------+--------|
* S Le ue ve
*
* For the 24-bit COMPRESSION_SGILOG24 color format, the data is stored as:
*
* 10 14
* |----------|--------------|
* Le' Ce
*
* There is no sign bit in the 24-bit case, and the (u,v) chromaticity is
* encoded as an index for optimal color resolution. The 10 log bits are
* defined by the following conversions:
*
* L = 2^((Le'+.5)/64 - 12) # real from 10-bit
*
* Le' = floor( 64*(log2(L) + 12) ) # 10-bit from real
*
* The 10 bits of the smaller format may be converted into the 15 bits of
* the larger format by multiplying by 4 and adding 13314. Obviously,
* a smaller range of magnitudes is covered (about 5 orders of magnitude
* instead of 38), and the lack of a sign bit means that negative luminances
* are not allowed. (Well, they aren't allowed in the real world, either,
* but they are useful for certain types of image processing.)
*
* The desired user format is controlled by the setting the internal
* pseudo tag TIFFTAG_SGILOGDATAFMT to one of:
* SGILOGDATAFMT_FLOAT = IEEE 32-bit float XYZ values
* SGILOGDATAFMT_16BIT = 16-bit integer encodings of logL, u and v
* Raw data i/o is also possible using:
* SGILOGDATAFMT_RAW = 32-bit unsigned integer with encoded pixel
* In addition, the following decoding is provided for ease of display:
* SGILOGDATAFMT_8BIT = 8-bit default RGB gamma-corrected values
*
* For grayscale images, we provide the following data formats:
* SGILOGDATAFMT_FLOAT = IEEE 32-bit float Y values
* SGILOGDATAFMT_16BIT = 16-bit integer w/ encoded luminance
* SGILOGDATAFMT_8BIT = 8-bit gray monitor values
*
* Note that the COMPRESSION_SGILOG applies a simple run-length encoding
* scheme by separating the logL, u and v bytes for each row and applying
* a PackBits type of compression. Since the 24-bit encoding is not
* adaptive, the 32-bit color format takes less space in many cases.
*
* Further control is provided over the conversion from higher-resolution
* formats to final encoded values through the pseudo tag
* TIFFTAG_SGILOGENCODE:
* SGILOGENCODE_NODITHER = do not dither encoded values
* SGILOGENCODE_RANDITHER = apply random dithering during encoding
*
* The default value of this tag is SGILOGENCODE_NODITHER for
* COMPRESSION_SGILOG to maximize run-length encoding and
* SGILOGENCODE_RANDITHER for COMPRESSION_SGILOG24 to turn
* quantization errors into noise.
*/
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
/*
* State block for each open TIFF
* file using LogLuv compression/decompression.
*/
typedef struct logLuvState LogLuvState;
struct logLuvState {
int user_datafmt; /* user data format */
int encode_meth; /* encoding method */
int pixel_size; /* bytes per pixel */
uint8* tbuf; /* translation buffer */
tmsize_t tbuflen; /* buffer length */
void (*tfunc)(LogLuvState*, uint8*, tmsize_t);
TIFFVSetMethod vgetparent; /* super-class method */
TIFFVSetMethod vsetparent; /* super-class method */
};
#define DecoderState(tif) ((LogLuvState*) (tif)->tif_data)
#define EncoderState(tif) ((LogLuvState*) (tif)->tif_data)
#define SGILOGDATAFMT_UNKNOWN -1
#define MINRUN 4 /* minimum run length */
/*
* Decode a string of 16-bit gray pixels.
*/
static int
LogL16Decode(TIFF* tif, uint8* op, tmsize_t occ, uint16 s)
{
static const char module[] = "LogL16Decode";
LogLuvState* sp = DecoderState(tif);
int shft;
tmsize_t i;
tmsize_t npixels;
unsigned char* bp;
int16* tp;
int16 b;
tmsize_t cc;
int rc;
assert(s == 0);
assert(sp != NULL);
npixels = occ / sp->pixel_size;
if (sp->user_datafmt == SGILOGDATAFMT_16BIT)
tp = (int16*) op;
else {
assert(sp->tbuflen >= npixels);
tp = (int16*) sp->tbuf;
}
_TIFFmemset((void*) tp, 0, npixels*sizeof (tp[0]));
bp = (unsigned char*) tif->tif_rawcp;
cc = tif->tif_rawcc;
/* get each byte string */
for (shft = 2*8; (shft -= 8) >= 0; ) {
for (i = 0; i < npixels && cc > 0; )
if (*bp >= 128) { /* run */
rc = *bp++ + (2-128); /* TODO: potential input buffer overrun when decoding corrupt or truncated data */
b = (int16)(*bp++ << shft);
cc -= 2;
while (rc-- && i < npixels)
tp[i++] |= b;
} else { /* non-run */
rc = *bp++; /* nul is noop */
while (--cc && rc-- && i < npixels)
tp[i++] |= (int16)*bp++ << shft;
}
if (i != npixels) {
#if defined(__WIN32__) && (defined(_MSC_VER) || defined(__MINGW32__))
TIFFErrorExt(tif->tif_clientdata, module,
"Not enough data at row %lu (short %I64d pixels)",
(unsigned long) tif->tif_row,
(unsigned __int64) (npixels - i));
#else
TIFFErrorExt(tif->tif_clientdata, module,
"Not enough data at row %lu (short %llu pixels)",
(unsigned long) tif->tif_row,
(unsigned long long) (npixels - i));
#endif
tif->tif_rawcp = (uint8*) bp;
tif->tif_rawcc = cc;
return (0);
}
}
(*sp->tfunc)(sp, op, npixels);
tif->tif_rawcp = (uint8*) bp;
tif->tif_rawcc = cc;
return (1);
}
/*
* Decode a string of 24-bit pixels.
*/
static int
LogLuvDecode24(TIFF* tif, uint8* op, tmsize_t occ, uint16 s)
{
static const char module[] = "LogLuvDecode24";
LogLuvState* sp = DecoderState(tif);
tmsize_t cc;
tmsize_t i;
tmsize_t npixels;
unsigned char* bp;
uint32* tp;
assert(s == 0);
assert(sp != NULL);
npixels = occ / sp->pixel_size;
if (sp->user_datafmt == SGILOGDATAFMT_RAW)
tp = (uint32 *)op;
else {
assert(sp->tbuflen >= npixels);
tp = (uint32 *) sp->tbuf;
}
/* copy to array of uint32 */
bp = (unsigned char*) tif->tif_rawcp;
cc = tif->tif_rawcc;
for (i = 0; i < npixels && cc > 0; i++) {
tp[i] = bp[0] << 16 | bp[1] << 8 | bp[2];
bp += 3;
cc -= 3;
}
tif->tif_rawcp = (uint8*) bp;
tif->tif_rawcc = cc;
if (i != npixels) {
#if defined(__WIN32__) && (defined(_MSC_VER) || defined(__MINGW32__))
TIFFErrorExt(tif->tif_clientdata, module,
"Not enough data at row %lu (short %I64d pixels)",
(unsigned long) tif->tif_row,
(unsigned __int64) (npixels - i));
#else
TIFFErrorExt(tif->tif_clientdata, module,
"Not enough data at row %lu (short %llu pixels)",
(unsigned long) tif->tif_row,
(unsigned long long) (npixels - i));
#endif
return (0);
}
(*sp->tfunc)(sp, op, npixels);
return (1);
}
/*
* Decode a string of 32-bit pixels.
*/
static int
LogLuvDecode32(TIFF* tif, uint8* op, tmsize_t occ, uint16 s)
{
static const char module[] = "LogLuvDecode32";
LogLuvState* sp;
int shft;
tmsize_t i;
tmsize_t npixels;
unsigned char* bp;
uint32* tp;
uint32 b;
tmsize_t cc;
int rc;
assert(s == 0);
sp = DecoderState(tif);
assert(sp != NULL);
npixels = occ / sp->pixel_size;
if (sp->user_datafmt == SGILOGDATAFMT_RAW)
tp = (uint32*) op;
else {
assert(sp->tbuflen >= npixels);
tp = (uint32*) sp->tbuf;
}
_TIFFmemset((void*) tp, 0, npixels*sizeof (tp[0]));
bp = (unsigned char*) tif->tif_rawcp;
cc = tif->tif_rawcc;
/* get each byte string */
for (shft = 4*8; (shft -= 8) >= 0; ) {
for (i = 0; i < npixels && cc > 0; )
if (*bp >= 128) { /* run */
rc = *bp++ + (2-128);
b = (uint32)*bp++ << shft;
cc -= 2; /* TODO: potential input buffer overrun when decoding corrupt or truncated data */
while (rc-- && i < npixels)
tp[i++] |= b;
} else { /* non-run */
rc = *bp++; /* nul is noop */
while (--cc && rc-- && i < npixels)
tp[i++] |= (uint32)*bp++ << shft;
}
if (i != npixels) {
#if defined(__WIN32__) && (defined(_MSC_VER) || defined(__MINGW32__))
TIFFErrorExt(tif->tif_clientdata, module,
"Not enough data at row %lu (short %I64d pixels)",
(unsigned long) tif->tif_row,
(unsigned __int64) (npixels - i));
#else
TIFFErrorExt(tif->tif_clientdata, module,
"Not enough data at row %lu (short %llu pixels)",
(unsigned long) tif->tif_row,
(unsigned long long) (npixels - i));
#endif
tif->tif_rawcp = (uint8*) bp;
tif->tif_rawcc = cc;
return (0);
}
}
(*sp->tfunc)(sp, op, npixels);
tif->tif_rawcp = (uint8*) bp;
tif->tif_rawcc = cc;
return (1);
}
/*
* Decode a strip of pixels. We break it into rows to
* maintain synchrony with the encode algorithm, which
* is row by row.
*/
static int
LogLuvDecodeStrip(TIFF* tif, uint8* bp, tmsize_t cc, uint16 s)
{
tmsize_t rowlen = TIFFScanlineSize(tif);
if (rowlen == 0)
return 0;
assert(cc%rowlen == 0);
while (cc && (*tif->tif_decoderow)(tif, bp, rowlen, s))
bp += rowlen, cc -= rowlen;
return (cc == 0);
}
/*
* Decode a tile of pixels. We break it into rows to
* maintain synchrony with the encode algorithm, which
* is row by row.
*/
static int
LogLuvDecodeTile(TIFF* tif, uint8* bp, tmsize_t cc, uint16 s)
{
tmsize_t rowlen = TIFFTileRowSize(tif);
if (rowlen == 0)
return 0;
assert(cc%rowlen == 0);
while (cc && (*tif->tif_decoderow)(tif, bp, rowlen, s))
bp += rowlen, cc -= rowlen;
return (cc == 0);
}
/*
* Encode a row of 16-bit pixels.
*/
static int
LogL16Encode(TIFF* tif, uint8* bp, tmsize_t cc, uint16 s)
{
LogLuvState* sp = EncoderState(tif);
int shft;
tmsize_t i;
tmsize_t j;
tmsize_t npixels;
uint8* op;
int16* tp;
int16 b;
tmsize_t occ;
int rc=0, mask;
tmsize_t beg;
assert(s == 0);
assert(sp != NULL);
npixels = cc / sp->pixel_size;
if (sp->user_datafmt == SGILOGDATAFMT_16BIT)
tp = (int16*) bp;
else {
tp = (int16*) sp->tbuf;
assert(sp->tbuflen >= npixels);
(*sp->tfunc)(sp, bp, npixels);
}
/* compress each byte string */
op = tif->tif_rawcp;
occ = tif->tif_rawdatasize - tif->tif_rawcc;
for (shft = 2*8; (shft -= 8) >= 0; )
for (i = 0; i < npixels; i += rc) {
if (occ < 4) {
tif->tif_rawcp = op;
tif->tif_rawcc = tif->tif_rawdatasize - occ;
if (!TIFFFlushData1(tif))
return (-1);
op = tif->tif_rawcp;
occ = tif->tif_rawdatasize - tif->tif_rawcc;
}
mask = 0xff << shft; /* find next run */
for (beg = i; beg < npixels; beg += rc) {
b = (int16) (tp[beg] & mask);
rc = 1;
while (rc < 127+2 && beg+rc < npixels &&
(tp[beg+rc] & mask) == b)
rc++;
if (rc >= MINRUN)
break; /* long enough */
}
if (beg-i > 1 && beg-i < MINRUN) {
b = (int16) (tp[i] & mask);/*check short run */
j = i+1;
while ((tp[j++] & mask) == b)
if (j == beg) {
*op++ = (uint8)(128-2+j-i);
*op++ = (uint8)(b >> shft);
occ -= 2;
i = beg;
break;
}
}
while (i < beg) { /* write out non-run */
if ((j = beg-i) > 127) j = 127;
if (occ < j+3) {
tif->tif_rawcp = op;
tif->tif_rawcc = tif->tif_rawdatasize - occ;
if (!TIFFFlushData1(tif))
return (-1);
op = tif->tif_rawcp;
occ = tif->tif_rawdatasize - tif->tif_rawcc;
}
*op++ = (uint8) j; occ--;
while (j--) {
*op++ = (uint8) (tp[i++] >> shft & 0xff);
occ--;
}
}
if (rc >= MINRUN) { /* write out run */
*op++ = (uint8) (128-2+rc);
*op++ = (uint8) (tp[beg] >> shft & 0xff);
occ -= 2;
} else
rc = 0;
}
tif->tif_rawcp = op;
tif->tif_rawcc = tif->tif_rawdatasize - occ;
return (1);
}
/*
* Encode a row of 24-bit pixels.
*/
static int
LogLuvEncode24(TIFF* tif, uint8* bp, tmsize_t cc, uint16 s)
{
LogLuvState* sp = EncoderState(tif);
tmsize_t i;
tmsize_t npixels;
tmsize_t occ;
uint8* op;
uint32* tp;
assert(s == 0);
assert(sp != NULL);
npixels = cc / sp->pixel_size;
if (sp->user_datafmt == SGILOGDATAFMT_RAW)
tp = (uint32*) bp;
else {
tp = (uint32*) sp->tbuf;
assert(sp->tbuflen >= npixels);
(*sp->tfunc)(sp, bp, npixels);
}
/* write out encoded pixels */
op = tif->tif_rawcp;
occ = tif->tif_rawdatasize - tif->tif_rawcc;
for (i = npixels; i--; ) {
if (occ < 3) {
tif->tif_rawcp = op;
tif->tif_rawcc = tif->tif_rawdatasize - occ;
if (!TIFFFlushData1(tif))
return (-1);
op = tif->tif_rawcp;
occ = tif->tif_rawdatasize - tif->tif_rawcc;
}
*op++ = (uint8)(*tp >> 16);
*op++ = (uint8)(*tp >> 8 & 0xff);
*op++ = (uint8)(*tp++ & 0xff);
occ -= 3;
}
tif->tif_rawcp = op;
tif->tif_rawcc = tif->tif_rawdatasize - occ;
return (1);
}
/*
* Encode a row of 32-bit pixels.
*/
static int
LogLuvEncode32(TIFF* tif, uint8* bp, tmsize_t cc, uint16 s)
{
LogLuvState* sp = EncoderState(tif);
int shft;
tmsize_t i;
tmsize_t j;
tmsize_t npixels;
uint8* op;
uint32* tp;
uint32 b;
tmsize_t occ;
int rc=0, mask;
tmsize_t beg;
assert(s == 0);
assert(sp != NULL);
npixels = cc / sp->pixel_size;
if (sp->user_datafmt == SGILOGDATAFMT_RAW)
tp = (uint32*) bp;
else {
tp = (uint32*) sp->tbuf;
assert(sp->tbuflen >= npixels);
(*sp->tfunc)(sp, bp, npixels);
}
/* compress each byte string */
op = tif->tif_rawcp;
occ = tif->tif_rawdatasize - tif->tif_rawcc;
for (shft = 4*8; (shft -= 8) >= 0; )
for (i = 0; i < npixels; i += rc) {
if (occ < 4) {
tif->tif_rawcp = op;
tif->tif_rawcc = tif->tif_rawdatasize - occ;
if (!TIFFFlushData1(tif))
return (-1);
op = tif->tif_rawcp;
occ = tif->tif_rawdatasize - tif->tif_rawcc;
}
mask = 0xff << shft; /* find next run */
for (beg = i; beg < npixels; beg += rc) {
b = tp[beg] & mask;
rc = 1;
while (rc < 127+2 && beg+rc < npixels &&
(tp[beg+rc] & mask) == b)
rc++;
if (rc >= MINRUN)
break; /* long enough */
}
if (beg-i > 1 && beg-i < MINRUN) {
b = tp[i] & mask; /* check short run */
j = i+1;
while ((tp[j++] & mask) == b)
if (j == beg) {
*op++ = (uint8)(128-2+j-i);
*op++ = (uint8)(b >> shft);
occ -= 2;
i = beg;
break;
}
}
while (i < beg) { /* write out non-run */
if ((j = beg-i) > 127) j = 127;
if (occ < j+3) {
tif->tif_rawcp = op;
tif->tif_rawcc = tif->tif_rawdatasize - occ;
if (!TIFFFlushData1(tif))
return (-1);
op = tif->tif_rawcp;
occ = tif->tif_rawdatasize - tif->tif_rawcc;
}
*op++ = (uint8) j; occ--;
while (j--) {
*op++ = (uint8)(tp[i++] >> shft & 0xff);
occ--;
}
}
if (rc >= MINRUN) { /* write out run */
*op++ = (uint8) (128-2+rc);
*op++ = (uint8)(tp[beg] >> shft & 0xff);
occ -= 2;
} else
rc = 0;
}
tif->tif_rawcp = op;
tif->tif_rawcc = tif->tif_rawdatasize - occ;
return (1);
}
/*
* Encode a strip of pixels. We break it into rows to
* avoid encoding runs across row boundaries.
*/
static int
LogLuvEncodeStrip(TIFF* tif, uint8* bp, tmsize_t cc, uint16 s)
{
tmsize_t rowlen = TIFFScanlineSize(tif);
if (rowlen == 0)
return 0;
assert(cc%rowlen == 0);
while (cc && (*tif->tif_encoderow)(tif, bp, rowlen, s) == 1)
bp += rowlen, cc -= rowlen;
return (cc == 0);
}
/*
* Encode a tile of pixels. We break it into rows to
* avoid encoding runs across row boundaries.
*/
static int
LogLuvEncodeTile(TIFF* tif, uint8* bp, tmsize_t cc, uint16 s)
{
tmsize_t rowlen = TIFFTileRowSize(tif);
if (rowlen == 0)
return 0;
assert(cc%rowlen == 0);
while (cc && (*tif->tif_encoderow)(tif, bp, rowlen, s) == 1)
bp += rowlen, cc -= rowlen;
return (cc == 0);
}
/*
* Encode/Decode functions for converting to and from user formats.
*/
#include "uvcode.h"
#ifndef UVSCALE
#define U_NEU 0.210526316
#define V_NEU 0.473684211
#define UVSCALE 410.
#endif
#ifndef M_LN2
#define M_LN2 0.69314718055994530942
#endif
#ifndef M_PI
#define M_PI 3.14159265358979323846
#endif
#undef log2 /* Conflict with C'99 function */
#define log2(x) ((1./M_LN2)*log(x))
#undef exp2 /* Conflict with C'99 function */
#define exp2(x) exp(M_LN2*(x))
#define itrunc(x,m) ((m)==SGILOGENCODE_NODITHER ? \
(int)(x) : \
(int)((x) + rand()*(1./RAND_MAX) - .5))
#if !LOGLUV_PUBLIC
static
#endif
double
LogL16toY(int p16) /* compute luminance from 16-bit LogL */
{
int Le = p16 & 0x7fff;
double Y;
if (!Le)
return (0.);
Y = exp(M_LN2/256.*(Le+.5) - M_LN2*64.);
return (!(p16 & 0x8000) ? Y : -Y);
}
#if !LOGLUV_PUBLIC
static
#endif
int
LogL16fromY(double Y, int em) /* get 16-bit LogL from Y */
{
if (Y >= 1.8371976e19)
return (0x7fff);
if (Y <= -1.8371976e19)
return (0xffff);
if (Y > 5.4136769e-20)
return itrunc(256.*(log2(Y) + 64.), em);
if (Y < -5.4136769e-20)
return (~0x7fff | itrunc(256.*(log2(-Y) + 64.), em));
return (0);
}
static void
L16toY(LogLuvState* sp, uint8* op, tmsize_t n)
{
int16* l16 = (int16*) sp->tbuf;
float* yp = (float*) op;
while (n-- > 0)
*yp++ = (float)LogL16toY(*l16++);
}
static void
L16toGry(LogLuvState* sp, uint8* op, tmsize_t n)
{
int16* l16 = (int16*) sp->tbuf;
uint8* gp = (uint8*) op;
while (n-- > 0) {
double Y = LogL16toY(*l16++);
*gp++ = (uint8) ((Y <= 0.) ? 0 : (Y >= 1.) ? 255 : (int)(256.*sqrt(Y)));
}
}
static void
L16fromY(LogLuvState* sp, uint8* op, tmsize_t n)
{
int16* l16 = (int16*) sp->tbuf;
float* yp = (float*) op;
while (n-- > 0)
*l16++ = (int16) (LogL16fromY(*yp++, sp->encode_meth));
}
#if !LOGLUV_PUBLIC
static
#endif
void
XYZtoRGB24(float xyz[3], uint8 rgb[3])
{
double r, g, b;
/* assume CCIR-709 primaries */
r = 2.690*xyz[0] + -1.276*xyz[1] + -0.414*xyz[2];
g = -1.022*xyz[0] + 1.978*xyz[1] + 0.044*xyz[2];
b = 0.061*xyz[0] + -0.224*xyz[1] + 1.163*xyz[2];
/* assume 2.0 gamma for speed */
/* could use integer sqrt approx., but this is probably faster */
rgb[0] = (uint8)((r<=0.) ? 0 : (r >= 1.) ? 255 : (int)(256.*sqrt(r)));
rgb[1] = (uint8)((g<=0.) ? 0 : (g >= 1.) ? 255 : (int)(256.*sqrt(g)));
rgb[2] = (uint8)((b<=0.) ? 0 : (b >= 1.) ? 255 : (int)(256.*sqrt(b)));
}
#if !LOGLUV_PUBLIC
static
#endif
double
LogL10toY(int p10) /* compute luminance from 10-bit LogL */
{
if (p10 == 0)
return (0.);
return (exp(M_LN2/64.*(p10+.5) - M_LN2*12.));
}
#if !LOGLUV_PUBLIC
static
#endif
int
LogL10fromY(double Y, int em) /* get 10-bit LogL from Y */
{
if (Y >= 15.742)
return (0x3ff);
else if (Y <= .00024283)
return (0);
else
return itrunc(64.*(log2(Y) + 12.), em);
}
#define NANGLES 100
#define uv2ang(u, v) ( (NANGLES*.499999999/M_PI) \
* atan2((v)-V_NEU,(u)-U_NEU) + .5*NANGLES )
static int
oog_encode(double u, double v) /* encode out-of-gamut chroma */
{
static int oog_table[NANGLES];
static int initialized = 0;
register int i;
if (!initialized) { /* set up perimeter table */
double eps[NANGLES], ua, va, ang, epsa;
int ui, vi, ustep;
for (i = NANGLES; i--; )
eps[i] = 2.;
for (vi = UV_NVS; vi--; ) {
va = UV_VSTART + (vi+.5)*UV_SQSIZ;
ustep = uv_row[vi].nus-1;
if (vi == UV_NVS-1 || vi == 0 || ustep <= 0)
ustep = 1;
for (ui = uv_row[vi].nus-1; ui >= 0; ui -= ustep) {
ua = uv_row[vi].ustart + (ui+.5)*UV_SQSIZ;
ang = uv2ang(ua, va);
i = (int) ang;
epsa = fabs(ang - (i+.5));
if (epsa < eps[i]) {
oog_table[i] = uv_row[vi].ncum + ui;
eps[i] = epsa;
}
}
}
for (i = NANGLES; i--; ) /* fill any holes */
if (eps[i] > 1.5) {
int i1, i2;
for (i1 = 1; i1 < NANGLES/2; i1++)
if (eps[(i+i1)%NANGLES] < 1.5)
break;
for (i2 = 1; i2 < NANGLES/2; i2++)
if (eps[(i+NANGLES-i2)%NANGLES] < 1.5)
break;
if (i1 < i2)
oog_table[i] =
oog_table[(i+i1)%NANGLES];
else
oog_table[i] =
oog_table[(i+NANGLES-i2)%NANGLES];
}
initialized = 1;
}
i = (int) uv2ang(u, v); /* look up hue angle */
return (oog_table[i]);
}
#undef uv2ang
#undef NANGLES
#if !LOGLUV_PUBLIC
static
#endif
int
uv_encode(double u, double v, int em) /* encode (u',v') coordinates */
{
register int vi, ui;
if (v < UV_VSTART)
return oog_encode(u, v);
vi = itrunc((v - UV_VSTART)*(1./UV_SQSIZ), em);
if (vi >= UV_NVS)
return oog_encode(u, v);
if (u < uv_row[vi].ustart)
return oog_encode(u, v);
ui = itrunc((u - uv_row[vi].ustart)*(1./UV_SQSIZ), em);
if (ui >= uv_row[vi].nus)
return oog_encode(u, v);
return (uv_row[vi].ncum + ui);
}
#if !LOGLUV_PUBLIC
static
#endif
int
uv_decode(double *up, double *vp, int c) /* decode (u',v') index */
{
int upper, lower;
register int ui, vi;
if (c < 0 || c >= UV_NDIVS)
return (-1);
lower = 0; /* binary search */
upper = UV_NVS;
while (upper - lower > 1) {
vi = (lower + upper) >> 1;
ui = c - uv_row[vi].ncum;
if (ui > 0)
lower = vi;
else if (ui < 0)
upper = vi;
else {
lower = vi;
break;
}
}
vi = lower;
ui = c - uv_row[vi].ncum;
*up = uv_row[vi].ustart + (ui+.5)*UV_SQSIZ;
*vp = UV_VSTART + (vi+.5)*UV_SQSIZ;
return (0);
}
#if !LOGLUV_PUBLIC
static
#endif
void
LogLuv24toXYZ(uint32 p, float XYZ[3])
{
int Ce;
double L, u, v, s, x, y;
/* decode luminance */
L = LogL10toY(p>>14 & 0x3ff);
if (L <= 0.) {
XYZ[0] = XYZ[1] = XYZ[2] = 0.;
return;
}
/* decode color */
Ce = p & 0x3fff;
if (uv_decode(&u, &v, Ce) < 0) {
u = U_NEU; v = V_NEU;
}
s = 1./(6.*u - 16.*v + 12.);
x = 9.*u * s;
y = 4.*v * s;
/* convert to XYZ */
XYZ[0] = (float)(x/y * L);
XYZ[1] = (float)L;
XYZ[2] = (float)((1.-x-y)/y * L);
}
#if !LOGLUV_PUBLIC
static
#endif
uint32
LogLuv24fromXYZ(float XYZ[3], int em)
{
int Le, Ce;
double u, v, s;
/* encode luminance */
Le = LogL10fromY(XYZ[1], em);
/* encode color */
s = XYZ[0] + 15.*XYZ[1] + 3.*XYZ[2];
if (!Le || s <= 0.) {
u = U_NEU;
v = V_NEU;
} else {
u = 4.*XYZ[0] / s;
v = 9.*XYZ[1] / s;
}
Ce = uv_encode(u, v, em);
if (Ce < 0) /* never happens */
Ce = uv_encode(U_NEU, V_NEU, SGILOGENCODE_NODITHER);
/* combine encodings */
return (Le << 14 | Ce);
}
static void
Luv24toXYZ(LogLuvState* sp, uint8* op, tmsize_t n)
{
uint32* luv = (uint32*) sp->tbuf;
float* xyz = (float*) op;
while (n-- > 0) {
LogLuv24toXYZ(*luv, xyz);
xyz += 3;
luv++;
}
}
static void
Luv24toLuv48(LogLuvState* sp, uint8* op, tmsize_t n)
{
uint32* luv = (uint32*) sp->tbuf;
int16* luv3 = (int16*) op;
while (n-- > 0) {
double u, v;