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tif_luv.c

/* $Id: tif_luv.c,v 1.17 2006/03/16 12:38:24 dron Exp $ */

/*
 * 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 */

      tidata_t*         tbuf;       /* translation buffer */
      int               tbuflen;    /* buffer length */
      void (*tfunc)(LogLuvState*, tidata_t, int);

      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, tidata_t op, tsize_t occ, tsample_t s)
{
      LogLuvState* sp = DecoderState(tif);
      int shft, i, npixels;
      unsigned char* bp;
      int16* tp;
      int16 b;
      int cc, 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((tdata_t) 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);
                        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) {
                  TIFFErrorExt(tif->tif_clientdata, tif->tif_name,
            "LogL16Decode: Not enough data at row %d (short %d pixels)",
                      tif->tif_row, npixels - i);
                  tif->tif_rawcp = (tidata_t) bp;
                  tif->tif_rawcc = cc;
                  return (0);
            }
      }
      (*sp->tfunc)(sp, op, npixels);
      tif->tif_rawcp = (tidata_t) bp;
      tif->tif_rawcc = cc;
      return (1);
}

/*
 * Decode a string of 24-bit pixels.
 */
static int
LogLuvDecode24(TIFF* tif, tidata_t op, tsize_t occ, tsample_t s)
{
      LogLuvState* sp = DecoderState(tif);
      int cc, i, 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 = (tidata_t) bp;
      tif->tif_rawcc = cc;
      if (i != npixels) {
            TIFFErrorExt(tif->tif_clientdata, tif->tif_name,
          "LogLuvDecode24: Not enough data at row %d (short %d pixels)",
                tif->tif_row, npixels - i);
            return (0);
      }
      (*sp->tfunc)(sp, op, npixels);
      return (1);
}

/*
 * Decode a string of 32-bit pixels.
 */
static int
LogLuvDecode32(TIFF* tif, tidata_t op, tsize_t occ, tsample_t s)
{
      LogLuvState* sp;
      int shft, i, npixels;
      unsigned char* bp;
      uint32* tp;
      uint32 b;
      int cc, 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((tdata_t) 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;
                        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) {
                  TIFFErrorExt(tif->tif_clientdata, tif->tif_name,
            "LogLuvDecode32: Not enough data at row %d (short %d pixels)",
                      tif->tif_row, npixels - i);
                  tif->tif_rawcp = (tidata_t) bp;
                  tif->tif_rawcc = cc;
                  return (0);
            }
      }
      (*sp->tfunc)(sp, op, npixels);
      tif->tif_rawcp = (tidata_t) 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, tidata_t bp, tsize_t cc, tsample_t s)
{
      tsize_t rowlen = TIFFScanlineSize(tif);

      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, tidata_t bp, tsize_t cc, tsample_t s)
{
      tsize_t rowlen = TIFFTileRowSize(tif);

      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, tidata_t bp, tsize_t cc, tsample_t s)
{
      LogLuvState* sp = EncoderState(tif);
      int shft, i, j, npixels;
      tidata_t op;
      int16* tp;
      int16 b;
      int occ, rc=0, mask, 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++ = (tidataval_t)(128-2+j-i);
                                        *op++ = (tidataval_t) (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++ = (tidataval_t) j; occ--;
                        while (j--) {
                              *op++ = (tidataval_t) (tp[i++] >> shft & 0xff);
                              occ--;
                        }
                  }
                  if (rc >= MINRUN) {           /* write out run */
                        *op++ = (tidataval_t) (128-2+rc);
                        *op++ = (tidataval_t) (tp[beg] >> shft & 0xff);
                        occ -= 2;
                  } else
                        rc = 0;
            }
      tif->tif_rawcp = op;
      tif->tif_rawcc = tif->tif_rawdatasize - occ;

      return (0);
}

/*
 * Encode a row of 24-bit pixels.
 */
static int
LogLuvEncode24(TIFF* tif, tidata_t bp, tsize_t cc, tsample_t s)
{
      LogLuvState* sp = EncoderState(tif);
      int i, npixels, occ;
      tidata_t 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++ = (tidataval_t)(*tp >> 16);
            *op++ = (tidataval_t)(*tp >> 8 & 0xff);
            *op++ = (tidataval_t)(*tp++ & 0xff);
            occ -= 3;
      }
      tif->tif_rawcp = op;
      tif->tif_rawcc = tif->tif_rawdatasize - occ;

      return (0);
}

/*
 * Encode a row of 32-bit pixels.
 */
static int
LogLuvEncode32(TIFF* tif, tidata_t bp, tsize_t cc, tsample_t s)
{
      LogLuvState* sp = EncoderState(tif);
      int shft, i, j, npixels;
      tidata_t op;
      uint32* tp;
      uint32 b;
      int occ, rc=0, mask, 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++ = (tidataval_t)(128-2+j-i);
                                    *op++ = (tidataval_t)(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++ = (tidataval_t) j; occ--;
                        while (j--) {
                              *op++ = (tidataval_t)(tp[i++] >> shft & 0xff);
                              occ--;
                        }
                  }
                  if (rc >= MINRUN) {           /* write out run */
                        *op++ = (tidataval_t) (128-2+rc);
                        *op++ = (tidataval_t)(tp[beg] >> shft & 0xff);
                        occ -= 2;
                  } else
                        rc = 0;
            }
      tif->tif_rawcp = op;
      tif->tif_rawcc = tif->tif_rawdatasize - occ;

      return (0);
}

/*
 * Encode a strip of pixels.  We break it into rows to
 * avoid encoding runs across row boundaries.
 */
static int
LogLuvEncodeStrip(TIFF* tif, tidata_t bp, tsize_t cc, tsample_t s)
{
      tsize_t rowlen = TIFFScanlineSize(tif);

      assert(cc%rowlen == 0);
      while (cc && (*tif->tif_encoderow)(tif, bp, rowlen, s) == 0)
            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, tidata_t bp, tsize_t cc, tsample_t s)
{
      tsize_t rowlen = TIFFTileRowSize(tif);

      assert(cc%rowlen == 0);
      while (cc && (*tif->tif_encoderow)(tif, bp, rowlen, s) == 0)
            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
#define log2(x)         ((1./M_LN2)*log(x))
#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, tidata_t op, int n)
{
      int16* l16 = (int16*) sp->tbuf;
      float* yp = (float*) op;

      while (n-- > 0)
            *yp++ = (float)LogL16toY(*l16++);
}

static void
L16toGry(LogLuvState* sp, tidata_t op, int 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, tidata_t op, int 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, tidata_t op, int n)
{
      uint32* luv = (uint32*) sp->tbuf;
      float* xyz = (float*) op;

      while (n-- > 0) {
            LogLuv24toXYZ(*luv, xyz);
            xyz += 3;
            luv++;
      }
}

static void
Luv24toLuv48(LogLuvState* sp, tidata_t op, int n)
{
      uint32* luv = (uint32*) sp->tbuf;
      int16* luv3 = (int16*) op;

      while (n-- > 0) {
            double u, v;

            *luv3++ = (int16)((*luv >> 12 & 0xffd) + 13314);
            if (uv_decode(&u, &v, *luv&0x3fff) < 0) {
                  u = U_NEU;
                  v = V_NEU;
            }
            *luv3++ = (int16)(u * (1L<<15));
            *luv3++ = (int16)(v * (1L<<15));
            luv++;
      }
}

static void
Luv24toRGB(LogLuvState* sp, tidata_t op, int n)
{
      uint32* luv = (uint32*) sp->tbuf;
      uint8* rgb = (uint8*) op;

      while (n-- > 0) {
            float xyz[3];

            LogLuv24toXYZ(*luv++, xyz);
            XYZtoRGB24(xyz, rgb);
            rgb += 3;
      }
}

static void
Luv24fromXYZ(LogLuvState* sp, tidata_t op, int n)
{
      uint32* luv = (uint32*) sp->tbuf;
      float* xyz = (float*) op;

      while (n-- > 0) {
            *luv++ = LogLuv24fromXYZ(xyz, sp->encode_meth);
            xyz += 3;
      }
}

static void
Luv24fromLuv48(LogLuvState* sp, tidata_t op, int n)
{
      uint32* luv = (uint32*) sp->tbuf;
      int16* luv3 = (int16*) op;

      while (n-- > 0) {
            int Le, Ce;

            if (luv3[0] <= 0)
                  Le = 0;
            else if (luv3[0] >= (1<<12)+3314)
                  Le = (1<<10) - 1;
            else if (sp->encode_meth == SGILOGENCODE_NODITHER)
                  Le = (luv3[0]-3314) >> 2;
            else
                  Le = itrunc(.25*(luv3[0]-3314.), sp->encode_meth);

            Ce = uv_encode((luv3[1]+.5)/(1<<15), (luv3[2]+.5)/(1<<15),
                              sp->encode_meth);
            if (Ce < 0) /* never happens */
                  Ce = uv_encode(U_NEU, V_NEU, SGILOGENCODE_NODITHER);
            *luv++ = (uint32)Le << 14 | Ce;
            luv3 += 3;
      }
}

#if !LOGLUV_PUBLIC
static
#endif
void
LogLuv32toXYZ(uint32 p, float XYZ[3])
{
      double      L, u, v, s, x, y;
                              /* decode luminance */
      L = LogL16toY((int)p >> 16);
      if (L <= 0.) {
            XYZ[0] = XYZ[1] = XYZ[2] = 0.;
            return;
      }
                              /* decode color */
      u = 1./UVSCALE * ((p>>8 & 0xff) + .5);
      v = 1./UVSCALE * ((p & 0xff) + .5);
      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
LogLuv32fromXYZ(float XYZ[3], int em)
{
      unsigned int      Le, ue, ve;
      double      u, v, s;
                              /* encode luminance */
      Le = (unsigned int)LogL16fromY(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;
      }
      if (u <= 0.) ue = 0;
      else ue = itrunc(UVSCALE*u, em);
      if (ue > 255) ue = 255;
      if (v <= 0.) ve = 0;
      else ve = itrunc(UVSCALE*v, em);
      if (ve > 255) ve = 255;
                              /* combine encodings */
      return (Le << 16 | ue << 8 | ve);
}

static void
Luv32toXYZ(LogLuvState* sp, tidata_t op, int n)
{
      uint32* luv = (uint32*) sp->tbuf;
      float* xyz = (float*) op;

      while (n-- > 0) {
            LogLuv32toXYZ(*luv++, xyz);
            xyz += 3;
      }
}

static void
Luv32toLuv48(LogLuvState* sp, tidata_t op, int n)
{
      uint32* luv = (uint32*) sp->tbuf;
      int16* luv3 = (int16*) op;

      while (n-- > 0) {
            double u, v;

            *luv3++ = (int16)(*luv >> 16);
            u = 1./UVSCALE * ((*luv>>8 & 0xff) + .5);
            v = 1./UVSCALE * ((*luv & 0xff) + .5);
            *luv3++ = (int16)(u * (1L<<15));
            *luv3++ = (int16)(v * (1L<<15));
            luv++;
      }
}

static void
Luv32toRGB(LogLuvState* sp, tidata_t op, int n)
{
      uint32* luv = (uint32*) sp->tbuf;
      uint8* rgb = (uint8*) op;

      while (n-- > 0) {
            float xyz[3];

            LogLuv32toXYZ(*luv++, xyz);
            XYZtoRGB24(xyz, rgb);
            rgb += 3;
      }
}

static void
Luv32fromXYZ(LogLuvState* sp, tidata_t op, int n)
{
      uint32* luv = (uint32*) sp->tbuf;
      float* xyz = (float*) op;

      while (n-- > 0) {
            *luv++ = LogLuv32fromXYZ(xyz, sp->encode_meth);
            xyz += 3;
      }
}

static void
Luv32fromLuv48(LogLuvState* sp, tidata_t op, int n)
{
      uint32* luv = (uint32*) sp->tbuf;
      int16* luv3 = (int16*) op;

      if (sp->encode_meth == SGILOGENCODE_NODITHER) {
            while (n-- > 0) {
                  *luv++ = (uint32)luv3[0] << 16 |
                        (luv3[1]*(uint32)(UVSCALE+.5) >> 7 & 0xff00) |
                        (luv3[2]*(uint32)(UVSCALE+.5) >> 15 & 0xff);
                  luv3 += 3;
            }
            return;
      }
      while (n-- > 0) {
            *luv++ = (uint32)luv3[0] << 16 |
      (itrunc(luv3[1]*(UVSCALE/(1<<15)), sp->encode_meth) << 8 & 0xff00) |
            (itrunc(luv3[2]*(UVSCALE/(1<<15)), sp->encode_meth) & 0xff);
            luv3 += 3;
      }
}

static void
_logLuvNop(LogLuvState* sp, tidata_t op, int n)
{
      (void) sp; (void) op; (void) n;
}

static int
LogL16GuessDataFmt(TIFFDirectory *td)
{
#define     PACK(s,b,f) (((b)<<6)|((s)<<3)|(f))
      switch (PACK(td->td_samplesperpixel, td->td_bitspersample, td->td_sampleformat)) {
      case PACK(1, 32, SAMPLEFORMAT_IEEEFP):
            return (SGILOGDATAFMT_FLOAT);
      case PACK(1, 16, SAMPLEFORMAT_VOID):
      case PACK(1, 16, SAMPLEFORMAT_INT):
      case PACK(1, 16, SAMPLEFORMAT_UINT):
            return (SGILOGDATAFMT_16BIT);
      case PACK(1,  8, SAMPLEFORMAT_VOID):
      case PACK(1,  8, SAMPLEFORMAT_UINT):
            return (SGILOGDATAFMT_8BIT);
      }
#undef PACK
      return (SGILOGDATAFMT_UNKNOWN);
}

static uint32
multiply(size_t m1, size_t m2)
{
      uint32      bytes = m1 * m2;

      if (m1 && bytes / m1 != m2)
            bytes = 0;

      return bytes;
}

static int
LogL16InitState(TIFF* tif)
{
      TIFFDirectory *td = &tif->tif_dir;
      LogLuvState* sp = DecoderState(tif);
      static const char module[] = "LogL16InitState";

      assert(sp != NULL);
      assert(td->td_photometric == PHOTOMETRIC_LOGL);

      /* for some reason, we can't do this in TIFFInitLogL16 */
      if (sp->user_datafmt == SGILOGDATAFMT_UNKNOWN)
            sp->user_datafmt = LogL16GuessDataFmt(td);
      switch (sp->user_datafmt) {
      case SGILOGDATAFMT_FLOAT:
            sp->pixel_size = sizeof (float);
            break;
      case SGILOGDATAFMT_16BIT:
            sp->pixel_size = sizeof (int16);
            break;
      case SGILOGDATAFMT_8BIT:
            sp->pixel_size = sizeof (uint8);
            break;
      default:
            TIFFErrorExt(tif->tif_clientdata, tif->tif_name,
                "No support for converting user data format to LogL");
            return (0);
      }
      sp->tbuflen = multiply(td->td_imagewidth, td->td_rowsperstrip);
      if (multiply(sp->tbuflen, sizeof (int16)) == 0 ||
          (sp->tbuf = (tidata_t*) _TIFFmalloc(sp->tbuflen * sizeof (int16))) == NULL) {
            TIFFErrorExt(tif->tif_clientdata, module, "%s: No space for SGILog translation buffer",
                tif->tif_name);
            return (0);
      }
      return (1);
}

static int
LogLuvGuessDataFmt(TIFFDirectory *td)
{
      int guess;

      /*
       * If the user didn't tell us their datafmt,
       * take our best guess from the bitspersample.
       */
#define     PACK(a,b)   (((a)<<3)|(b))
      switch (PACK(td->td_bitspersample, td->td_sampleformat)) {
      case PACK(32, SAMPLEFORMAT_IEEEFP):
            guess = SGILOGDATAFMT_FLOAT;
            break;
      case PACK(32, SAMPLEFORMAT_VOID):
      case PACK(32, SAMPLEFORMAT_UINT):
      case PACK(32, SAMPLEFORMAT_INT):
            guess = SGILOGDATAFMT_RAW;
            break;
      case PACK(16, SAMPLEFORMAT_VOID):
      case PACK(16, SAMPLEFORMAT_INT):
      case PACK(16, SAMPLEFORMAT_UINT):
            guess = SGILOGDATAFMT_16BIT;
            break;
      case PACK( 8, SAMPLEFORMAT_VOID):
      case PACK( 8, SAMPLEFORMAT_UINT):
            guess = SGILOGDATAFMT_8BIT;
            break;
      default:
            guess = SGILOGDATAFMT_UNKNOWN;
            break;
#undef PACK
      }
      /*
       * Double-check samples per pixel.
       */
      switch (td->td_samplesperpixel) {
      case 1:
            if (guess != SGILOGDATAFMT_RAW)
                  guess = SGILOGDATAFMT_UNKNOWN;
            break;
      case 3:
            if (guess == SGILOGDATAFMT_RAW)
                  guess = SGILOGDATAFMT_UNKNOWN;
            break;
      default:
            guess = SGILOGDATAFMT_UNKNOWN;
            break;
      }
      return (guess);
}

static int
LogLuvInitState(TIFF* tif)
{
      TIFFDirectory* td = &tif->tif_dir;
      LogLuvState* sp = DecoderState(tif);
      static const char module[] = "LogLuvInitState";

      assert(sp != NULL);
      assert(td->td_photometric == PHOTOMETRIC_LOGLUV);

      /* for some reason, we can't do this in TIFFInitLogLuv */
      if (td->td_planarconfig != PLANARCONFIG_CONTIG) {
            TIFFErrorExt(tif->tif_clientdata, module,
                "SGILog compression cannot handle non-contiguous data");
            return (0);
      }
      if (sp->user_datafmt == SGILOGDATAFMT_UNKNOWN)
            sp->user_datafmt = LogLuvGuessDataFmt(td);
      switch (sp->user_datafmt) {
      case SGILOGDATAFMT_FLOAT:
            sp->pixel_size = 3*sizeof (float);
            break;
      case SGILOGDATAFMT_16BIT:
            sp->pixel_size = 3*sizeof (int16);
            break;
      case SGILOGDATAFMT_RAW:
            sp->pixel_size = sizeof (uint32);
            break;
      case SGILOGDATAFMT_8BIT:
            sp->pixel_size = 3*sizeof (uint8);
            break;
      default:
            TIFFErrorExt(tif->tif_clientdata, tif->tif_name,
                "No support for converting user data format to LogLuv");
            return (0);
      }
      sp->tbuflen = multiply(td->td_imagewidth, td->td_rowsperstrip);
      if (multiply(sp->tbuflen, sizeof (uint32)) == 0 ||
          (sp->tbuf = (tidata_t*) _TIFFmalloc(sp->tbuflen * sizeof (uint32))) == NULL) {
            TIFFErrorExt(tif->tif_clientdata, module, "%s: No space for SGILog translation buffer",
                tif->tif_name);
            return (0);
      }
      return (1);
}

static int
LogLuvSetupDecode(TIFF* tif)
{
      LogLuvState* sp = DecoderState(tif);
      TIFFDirectory* td = &tif->tif_dir;

      tif->tif_postdecode = _TIFFNoPostDecode;
      switch (td->td_photometric) {
      case PHOTOMETRIC_LOGLUV:
            if (!LogLuvInitState(tif))
                  break;
            if (td->td_compression == COMPRESSION_SGILOG24) {
                  tif->tif_decoderow = LogLuvDecode24;
                  switch (sp->user_datafmt) {
                  case SGILOGDATAFMT_FLOAT:
                        sp->tfunc = Luv24toXYZ;
                        break;
                  case SGILOGDATAFMT_16BIT:
                        sp->tfunc = Luv24toLuv48;
                        break;
                  case SGILOGDATAFMT_8BIT:
                        sp->tfunc = Luv24toRGB;
                        break;
                  }
            } else {
                  tif->tif_decoderow = LogLuvDecode32;
                  switch (sp->user_datafmt) {
                  case SGILOGDATAFMT_FLOAT:
                        sp->tfunc = Luv32toXYZ;
                        break;
                  case SGILOGDATAFMT_16BIT:
                        sp->tfunc = Luv32toLuv48;
                        break;
                  case SGILOGDATAFMT_8BIT:
                        sp->tfunc = Luv32toRGB;
                        break;
                  }
            }
            return (1);
      case PHOTOMETRIC_LOGL:
            if (!LogL16InitState(tif))
                  break;
            tif->tif_decoderow = LogL16Decode;
            switch (sp->user_datafmt) {
            case SGILOGDATAFMT_FLOAT:
                  sp->tfunc = L16toY;
                  break;
            case SGILOGDATAFMT_8BIT:
                  sp->tfunc = L16toGry;
                  break;
            }
            return (1);
      default:
            TIFFErrorExt(tif->tif_clientdata, tif->tif_name,
    "Inappropriate photometric interpretation %d for SGILog compression; %s",
                td->td_photometric, "must be either LogLUV or LogL");
            break;
      }
      return (0);
}

static int
LogLuvSetupEncode(TIFF* tif)
{
      LogLuvState* sp = EncoderState(tif);
      TIFFDirectory* td = &tif->tif_dir;

      switch (td->td_photometric) {
      case PHOTOMETRIC_LOGLUV:
            if (!LogLuvInitState(tif))
                  break;
            if (td->td_compression == COMPRESSION_SGILOG24) {
                  tif->tif_encoderow = LogLuvEncode24;
                  switch (sp->user_datafmt) {
                  case SGILOGDATAFMT_FLOAT:
                        sp->tfunc = Luv24fromXYZ;
                        break;
                  case SGILOGDATAFMT_16BIT:
                        sp->tfunc = Luv24fromLuv48;
                        break;
                  case SGILOGDATAFMT_RAW:
                        break;
                  default:
                        goto notsupported;
                  }
            } else {
                  tif->tif_encoderow = LogLuvEncode32;
                  switch (sp->user_datafmt) {
                  case SGILOGDATAFMT_FLOAT:
                        sp->tfunc = Luv32fromXYZ;
                        break;
                  case SGILOGDATAFMT_16BIT:
                        sp->tfunc = Luv32fromLuv48;
                        break;
                  case SGILOGDATAFMT_RAW:
                        break;
                  default:
                        goto notsupported;
                  }
            }
            break;
      case PHOTOMETRIC_LOGL:
            if (!LogL16InitState(tif))
                  break;
            tif->tif_encoderow = LogL16Encode;
            switch (sp->user_datafmt) {
            case SGILOGDATAFMT_FLOAT:
                  sp->tfunc = L16fromY;
                  break;
            case SGILOGDATAFMT_16BIT:
                  break;
            default:
                  goto notsupported;
            }
            break;
      default:
            TIFFErrorExt(tif->tif_clientdata, tif->tif_name,
    "Inappropriate photometric interpretation %d for SGILog compression; %s",
                td->td_photometric, "must be either LogLUV or LogL");
            break;
      }
      return (1);
notsupported:
      TIFFErrorExt(tif->tif_clientdata, tif->tif_name,
          "SGILog compression supported only for %s, or raw data",
          td->td_photometric == PHOTOMETRIC_LOGL ? "Y, L" : "XYZ, Luv");
      return (0);
}

static void
LogLuvClose(TIFF* tif)
{
      TIFFDirectory *td = &tif->tif_dir;

      /*
       * For consistency, we always want to write out the same
       * bitspersample and sampleformat for our TIFF file,
       * regardless of the data format being used by the application.
       * Since this routine is called after tags have been set but
       * before they have been recorded in the file, we reset them here.
       */
      td->td_samplesperpixel =
          (td->td_photometric == PHOTOMETRIC_LOGL) ? 1 : 3;
      td->td_bitspersample = 16;
      td->td_sampleformat = SAMPLEFORMAT_INT;
}

static void
LogLuvCleanup(TIFF* tif)
{
      LogLuvState* sp = (LogLuvState *)tif->tif_data;

      assert(sp != 0);

      tif->tif_tagmethods.vgetfield = sp->vgetparent;
      tif->tif_tagmethods.vsetfield = sp->vsetparent;

      if (sp->tbuf)
            _TIFFfree(sp->tbuf);
      _TIFFfree(sp);
      tif->tif_data = NULL;

      _TIFFSetDefaultCompressionState(tif);
}

static int
LogLuvVSetField(TIFF* tif, ttag_t tag, va_list ap)
{
      LogLuvState* sp = DecoderState(tif);
      int bps, fmt;

      switch (tag) {
      case TIFFTAG_SGILOGDATAFMT:
            sp->user_datafmt = va_arg(ap, int);
            /*
             * Tweak the TIFF header so that the rest of libtiff knows what
             * size of data will be passed between app and library, and
             * assume that the app knows what it is doing and is not
             * confused by these header manipulations...
             */
            switch (sp->user_datafmt) {
            case SGILOGDATAFMT_FLOAT:
                  bps = 32, fmt = SAMPLEFORMAT_IEEEFP;
                  break;
            case SGILOGDATAFMT_16BIT:
                  bps = 16, fmt = SAMPLEFORMAT_INT;
                  break;
            case SGILOGDATAFMT_RAW:
                  bps = 32, fmt = SAMPLEFORMAT_UINT;
                  TIFFSetField(tif, TIFFTAG_SAMPLESPERPIXEL, 1);
                  break;
            case SGILOGDATAFMT_8BIT:
                  bps = 8, fmt = SAMPLEFORMAT_UINT;
                  break;
            default:
                  TIFFErrorExt(tif->tif_clientdata, tif->tif_name,
                      "Unknown data format %d for LogLuv compression",
                      sp->user_datafmt);
                  return (0);
            }
            TIFFSetField(tif, TIFFTAG_BITSPERSAMPLE, bps);
            TIFFSetField(tif, TIFFTAG_SAMPLEFORMAT, fmt);
            /*
             * Must recalculate sizes should bits/sample change.
             */
            tif->tif_tilesize = isTiled(tif) ? TIFFTileSize(tif) : (tsize_t) -1;
            tif->tif_scanlinesize = TIFFScanlineSize(tif);
            return (1);
      case TIFFTAG_SGILOGENCODE:
            sp->encode_meth = va_arg(ap, int);
            if (sp->encode_meth != SGILOGENCODE_NODITHER &&
                        sp->encode_meth != SGILOGENCODE_RANDITHER) {
                  TIFFErrorExt(tif->tif_clientdata, tif->tif_name,
                        "Unknown encoding %d for LogLuv compression",
                        sp->encode_meth);
                  return (0);
            }
            return (1);
      default:
            return (*sp->vsetparent)(tif, tag, ap);
      }
}

static int
LogLuvVGetField(TIFF* tif, ttag_t tag, va_list ap)
{
      LogLuvState *sp = (LogLuvState *)tif->tif_data;

      switch (tag) {
      case TIFFTAG_SGILOGDATAFMT:
            *va_arg(ap, int*) = sp->user_datafmt;
            return (1);
      default:
            return (*sp->vgetparent)(tif, tag, ap);
      }
}

static const TIFFFieldInfo LogLuvFieldInfo[] = {
    { TIFFTAG_SGILOGDATAFMT,    0, 0,     TIFF_SHORT, FIELD_PSEUDO,
      TRUE, FALSE,      "SGILogDataFmt"},
    { TIFFTAG_SGILOGENCODE,     0, 0, TIFF_SHORT,     FIELD_PSEUDO,
      TRUE, FALSE,      "SGILogEncode"}
};

int
TIFFInitSGILog(TIFF* tif, int scheme)
{
      static const char module[] = "TIFFInitSGILog";
      LogLuvState* sp;

      assert(scheme == COMPRESSION_SGILOG24 || scheme == COMPRESSION_SGILOG);

      /*
       * Allocate state block so tag methods have storage to record values.
       */
      tif->tif_data = (tidata_t) _TIFFmalloc(sizeof (LogLuvState));
      if (tif->tif_data == NULL)
            goto bad;
      sp = (LogLuvState*) tif->tif_data;
      _TIFFmemset((tdata_t)sp, 0, sizeof (*sp));
      sp->user_datafmt = SGILOGDATAFMT_UNKNOWN;
      sp->encode_meth = (scheme == COMPRESSION_SGILOG24) ?
                        SGILOGENCODE_RANDITHER : SGILOGENCODE_NODITHER;
      sp->tfunc = _logLuvNop;

      /*
       * Install codec methods.
       * NB: tif_decoderow & tif_encoderow are filled
       *     in at setup time.
       */
      tif->tif_setupdecode = LogLuvSetupDecode;
      tif->tif_decodestrip = LogLuvDecodeStrip;
      tif->tif_decodetile = LogLuvDecodeTile;
      tif->tif_setupencode = LogLuvSetupEncode;
      tif->tif_encodestrip = LogLuvEncodeStrip;
      tif->tif_encodetile = LogLuvEncodeTile;
      tif->tif_close = LogLuvClose;
      tif->tif_cleanup = LogLuvCleanup;

      /* override SetField so we can handle our private pseudo-tag */
      _TIFFMergeFieldInfo(tif, LogLuvFieldInfo,
                      TIFFArrayCount(LogLuvFieldInfo));
      sp->vgetparent = tif->tif_tagmethods.vgetfield;
      tif->tif_tagmethods.vgetfield = LogLuvVGetField;   /* hook for codec tags */
      sp->vsetparent = tif->tif_tagmethods.vsetfield;
      tif->tif_tagmethods.vsetfield = LogLuvVSetField;   /* hook for codec tags */

      return (1);
bad:
      TIFFErrorExt(tif->tif_clientdata, module,
                 "%s: No space for LogLuv state block", tif->tif_name);
      return (0);
}
#endif /* LOGLUV_SUPPORT */

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