tif_jpeg.c

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/* $Id: tif_jpeg.c,v 1.50.2.9 2010-06-14 02:47:16 fwarmerdam Exp $ */

/*
 * Copyright (c) 1994-1997 Sam Leffler
 * Copyright (c) 1994-1997 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 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 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 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.
 */

#define WIN32_LEAN_AND_MEAN
#define VC_EXTRALEAN

#include "tiffiop.h"
#ifdef JPEG_SUPPORT

/*
 * TIFF Library
 *
 * JPEG Compression support per TIFF Technical Note #2
 * (*not* per the original TIFF 6.0 spec).
 *
 * This file is simply an interface to the libjpeg library written by
 * the Independent JPEG Group.  You need release 5 or later of the IJG
 * code, which you can find on the Internet at ftp.uu.net:/graphics/jpeg/.
 *
 * Contributed by Tom Lane <tgl@sss.pgh.pa.us>.
 */
#include <setjmp.h>

int TIFFFillStrip(TIFF*, tstrip_t);
int TIFFFillTile(TIFF*, ttile_t);

/* We undefine FAR to avoid conflict with JPEG definition */

#ifdef FAR
#undef FAR
#endif

/*
  Libjpeg's jmorecfg.h defines INT16 and INT32, but only if XMD_H is
  not defined.  Unfortunately, the MinGW and Borland compilers include
  a typedef for INT32, which causes a conflict.  MSVC does not include
  a conficting typedef given the headers which are included.
*/
#if defined(__BORLANDC__) || defined(__MINGW32__)
# define XMD_H 1
#endif

/*
   The windows RPCNDR.H file defines boolean, but defines it with the
   unsigned char size.  You should compile JPEG library using appropriate
   definitions in jconfig.h header, but many users compile library in wrong
   way. That causes errors of the following type:

   "JPEGLib: JPEG parameter struct mismatch: library thinks size is 432,
   caller expects 464"

   For such users we wil fix the problem here. See install.doc file from
   the JPEG library distribution for details.
*/

/* Define "boolean" as unsigned char, not int, per Windows custom. */
#if defined(WIN32) && !defined(__MINGW32__)
# ifndef __RPCNDR_H__            /* don't conflict if rpcndr.h already read */
   typedef unsigned char boolean;
# endif
# define HAVE_BOOLEAN            /* prevent jmorecfg.h from redefining it */
#endif

#include "jpeglib.h"
#include "jerror.h"

/*
 * We are using width_in_blocks which is supposed to be private to
 * libjpeg. Unfortunately, the libjpeg delivered with Cygwin has
 * renamed this member to width_in_data_units.  Since the header has
 * also renamed a define, use that unique define name in order to
 * detect the problem header and adjust to suit.
 */
#if defined(D_MAX_DATA_UNITS_IN_MCU)
#define width_in_blocks width_in_data_units
#endif

/*
 * On some machines it may be worthwhile to use _setjmp or sigsetjmp
 * in place of plain setjmp.  These macros will make it easier.
 */
#define SETJMP(jbuf)        setjmp(jbuf)
#define LONGJMP(jbuf,code)  longjmp(jbuf,code)
#define JMP_BUF         jmp_buf

typedef struct jpeg_destination_mgr jpeg_destination_mgr;
typedef struct jpeg_source_mgr jpeg_source_mgr;
typedef struct jpeg_error_mgr jpeg_error_mgr;

/*
 * State block for each open TIFF file using
 * libjpeg to do JPEG compression/decompression.
 *
 * libjpeg's visible state is either a jpeg_compress_struct
 * or jpeg_decompress_struct depending on which way we
 * are going.  comm can be used to refer to the fields
 * which are common to both.
 *
 * NB: cinfo is required to be the first member of JPEGState,
 *     so we can safely cast JPEGState* -> jpeg_xxx_struct*
 *     and vice versa!
 */
typedef struct {
    union {
        struct jpeg_compress_struct c;
        struct jpeg_decompress_struct d;
        struct jpeg_common_struct comm;
    } cinfo;            /* NB: must be first */
        int             cinfo_initialized;

    jpeg_error_mgr  err;        /* libjpeg error manager */
    JMP_BUF     exit_jmpbuf;    /* for catching libjpeg failures */
    /*
     * The following two members could be a union, but
     * they're small enough that it's not worth the effort.
     */
    jpeg_destination_mgr dest;  /* data dest for compression */
    jpeg_source_mgr src;        /* data source for decompression */
                    /* private state */
    TIFF*       tif;        /* back link needed by some code */
    uint16      photometric;    /* copy of PhotometricInterpretation */
    uint16      h_sampling; /* luminance sampling factors */
    uint16      v_sampling;
    tsize_t     bytesperline;   /* decompressed bytes per scanline */
    /* pointers to intermediate buffers when processing downsampled data */
    JSAMPARRAY  ds_buffer[MAX_COMPONENTS];
    int     scancount;  /* number of "scanlines" accumulated */
    int     samplesperclump;

    TIFFVGetMethod  vgetparent; /* super-class method */
    TIFFVSetMethod  vsetparent; /* super-class method */
    TIFFPrintMethod printdir;   /* super-class method */
    TIFFStripMethod defsparent; /* super-class method */
    TIFFTileMethod  deftparent; /* super-class method */
                    /* pseudo-tag fields */
    void*       jpegtables; /* JPEGTables tag value, or NULL */
    uint32      jpegtables_length; /* number of bytes in same */
    int     jpegquality;    /* Compression quality level */
    int     jpegcolormode;  /* Auto RGB<=>YCbCr convert? */
    int     jpegtablesmode; /* What to put in JPEGTables */

        int             ycbcrsampling_fetched;
    uint32      recvparams; /* encoded Class 2 session params */
    char*       subaddress; /* subaddress string */
    uint32      recvtime;   /* time spent receiving (secs) */
    char*       faxdcs;     /* encoded fax parameters (DCS, Table 2/T.30) */
} JPEGState;

#define JState(tif) ((JPEGState*)(tif)->tif_data)

static  int JPEGDecode(TIFF*, tidata_t, tsize_t, tsample_t);
static  int JPEGDecodeRaw(TIFF*, tidata_t, tsize_t, tsample_t);
static  int JPEGEncode(TIFF*, tidata_t, tsize_t, tsample_t);
static  int JPEGEncodeRaw(TIFF*, tidata_t, tsize_t, tsample_t);
static  int JPEGInitializeLibJPEG( TIFF * tif,
                                   int force_encode, int force_decode );

#define FIELD_JPEGTABLES    (FIELD_CODEC+0)
#define FIELD_RECVPARAMS    (FIELD_CODEC+1)
#define FIELD_SUBADDRESS    (FIELD_CODEC+2)
#define FIELD_RECVTIME      (FIELD_CODEC+3)
#define FIELD_FAXDCS        (FIELD_CODEC+4)

static const TIFFFieldInfo jpegFieldInfo[] = {
    { TIFFTAG_JPEGTABLES,    -3,-3, TIFF_UNDEFINED, FIELD_JPEGTABLES,
      FALSE,    TRUE,   "JPEGTables" },
    { TIFFTAG_JPEGQUALITY,   0, 0,  TIFF_ANY,   FIELD_PSEUDO,
      TRUE, FALSE,  "" },
    { TIFFTAG_JPEGCOLORMODE,     0, 0,  TIFF_ANY,   FIELD_PSEUDO,
      FALSE,    FALSE,  "" },
    { TIFFTAG_JPEGTABLESMODE,    0, 0,  TIFF_ANY,   FIELD_PSEUDO,
      FALSE,    FALSE,  "" },
    /* Specific for JPEG in faxes */
    { TIFFTAG_FAXRECVPARAMS,     1, 1, TIFF_LONG,   FIELD_RECVPARAMS,
      TRUE, FALSE,  "FaxRecvParams" },
    { TIFFTAG_FAXSUBADDRESS,    -1,-1, TIFF_ASCII,  FIELD_SUBADDRESS,
      TRUE, FALSE,  "FaxSubAddress" },
    { TIFFTAG_FAXRECVTIME,   1, 1, TIFF_LONG,   FIELD_RECVTIME,
      TRUE, FALSE,  "FaxRecvTime" },
    { TIFFTAG_FAXDCS,       -1, -1, TIFF_ASCII, FIELD_FAXDCS,
      TRUE, FALSE,  "FaxDcs" },
};
#define N(a)    (sizeof (a) / sizeof (a[0]))

/*
 * libjpeg interface layer.
 *
 * We use setjmp/longjmp to return control to libtiff
 * when a fatal error is encountered within the JPEG
 * library.  We also direct libjpeg error and warning
 * messages through the appropriate libtiff handlers.
 */

/*
 * Error handling routines (these replace corresponding
 * IJG routines from jerror.c).  These are used for both
 * compression and decompression.
 */
static void
TIFFjpeg_error_exit(j_common_ptr cinfo)
{
    JPEGState *sp = (JPEGState *) cinfo;    /* NB: cinfo assumed first */
    char buffer[JMSG_LENGTH_MAX];

    (*cinfo->err->format_message) (cinfo, buffer);
    TIFFErrorExt(sp->tif->tif_clientdata, "JPEGLib", "%s", buffer);     /* display the error message */
    jpeg_abort(cinfo);          /* clean up libjpeg state */
    LONGJMP(sp->exit_jmpbuf, 1);        /* return to libtiff caller */
}

/*
 * This routine is invoked only for warning messages,
 * since error_exit does its own thing and trace_level
 * is never set > 0.
 */
static void
TIFFjpeg_output_message(j_common_ptr cinfo)
{
    char buffer[JMSG_LENGTH_MAX];

    (*cinfo->err->format_message) (cinfo, buffer);
    TIFFWarningExt(((JPEGState *) cinfo)->tif->tif_clientdata, "JPEGLib", "%s", buffer);
}

/*
 * Interface routines.  This layer of routines exists
 * primarily to limit side-effects from using setjmp.
 * Also, normal/error returns are converted into return
 * values per libtiff practice.
 */
#define CALLJPEG(sp, fail, op)  (SETJMP((sp)->exit_jmpbuf) ? (fail) : (op))
#define CALLVJPEG(sp, op)   CALLJPEG(sp, 0, ((op),1))

static int
TIFFjpeg_create_compress(JPEGState* sp)
{
    /* initialize JPEG error handling */
    sp->cinfo.c.err = jpeg_std_error(&sp->err);
    sp->err.error_exit = TIFFjpeg_error_exit;
    sp->err.output_message = TIFFjpeg_output_message;

    return CALLVJPEG(sp, jpeg_create_compress(&sp->cinfo.c));
}

static int
TIFFjpeg_create_decompress(JPEGState* sp)
{
    /* initialize JPEG error handling */
    sp->cinfo.d.err = jpeg_std_error(&sp->err);
    sp->err.error_exit = TIFFjpeg_error_exit;
    sp->err.output_message = TIFFjpeg_output_message;

    return CALLVJPEG(sp, jpeg_create_decompress(&sp->cinfo.d));
}

static int
TIFFjpeg_set_defaults(JPEGState* sp)
{
    return CALLVJPEG(sp, jpeg_set_defaults(&sp->cinfo.c));
}

static int
TIFFjpeg_set_colorspace(JPEGState* sp, J_COLOR_SPACE colorspace)
{
    return CALLVJPEG(sp, jpeg_set_colorspace(&sp->cinfo.c, colorspace));
}

static int
TIFFjpeg_set_quality(JPEGState* sp, int quality, boolean force_baseline)
{
    return CALLVJPEG(sp,
        jpeg_set_quality(&sp->cinfo.c, quality, force_baseline));
}

static int
TIFFjpeg_suppress_tables(JPEGState* sp, boolean suppress)
{
    return CALLVJPEG(sp, jpeg_suppress_tables(&sp->cinfo.c, suppress));
}

static int
TIFFjpeg_start_compress(JPEGState* sp, boolean write_all_tables)
{
    return CALLVJPEG(sp,
        jpeg_start_compress(&sp->cinfo.c, write_all_tables));
}

static int
TIFFjpeg_write_scanlines(JPEGState* sp, JSAMPARRAY scanlines, int num_lines)
{
    return CALLJPEG(sp, -1, (int) jpeg_write_scanlines(&sp->cinfo.c,
        scanlines, (JDIMENSION) num_lines));
}

static int
TIFFjpeg_write_raw_data(JPEGState* sp, JSAMPIMAGE data, int num_lines)
{
    return CALLJPEG(sp, -1, (int) jpeg_write_raw_data(&sp->cinfo.c,
        data, (JDIMENSION) num_lines));
}

static int
TIFFjpeg_finish_compress(JPEGState* sp)
{
    return CALLVJPEG(sp, jpeg_finish_compress(&sp->cinfo.c));
}

static int
TIFFjpeg_write_tables(JPEGState* sp)
{
    return CALLVJPEG(sp, jpeg_write_tables(&sp->cinfo.c));
}

static int
TIFFjpeg_read_header(JPEGState* sp, boolean require_image)
{
    return CALLJPEG(sp, -1, jpeg_read_header(&sp->cinfo.d, require_image));
}

static int
TIFFjpeg_start_decompress(JPEGState* sp)
{
    return CALLVJPEG(sp, jpeg_start_decompress(&sp->cinfo.d));
}

static int
TIFFjpeg_read_scanlines(JPEGState* sp, JSAMPARRAY scanlines, int max_lines)
{
    return CALLJPEG(sp, -1, (int) jpeg_read_scanlines(&sp->cinfo.d,
        scanlines, (JDIMENSION) max_lines));
}

static int
TIFFjpeg_read_raw_data(JPEGState* sp, JSAMPIMAGE data, int max_lines)
{
    return CALLJPEG(sp, -1, (int) jpeg_read_raw_data(&sp->cinfo.d,
        data, (JDIMENSION) max_lines));
}

static int
TIFFjpeg_finish_decompress(JPEGState* sp)
{
    return CALLJPEG(sp, -1, (int) jpeg_finish_decompress(&sp->cinfo.d));
}

static int
TIFFjpeg_abort(JPEGState* sp)
{
    return CALLVJPEG(sp, jpeg_abort(&sp->cinfo.comm));
}

static int
TIFFjpeg_destroy(JPEGState* sp)
{
    return CALLVJPEG(sp, jpeg_destroy(&sp->cinfo.comm));
}

static JSAMPARRAY
TIFFjpeg_alloc_sarray(JPEGState* sp, int pool_id,
              JDIMENSION samplesperrow, JDIMENSION numrows)
{
    return CALLJPEG(sp, (JSAMPARRAY) NULL,
        (*sp->cinfo.comm.mem->alloc_sarray)
        (&sp->cinfo.comm, pool_id, samplesperrow, numrows));
}

/*
 * JPEG library destination data manager.
 * These routines direct compressed data from libjpeg into the
 * libtiff output buffer.
 */

static void
std_init_destination(j_compress_ptr cinfo)
{
    JPEGState* sp = (JPEGState*) cinfo;
    TIFF* tif = sp->tif;

    sp->dest.next_output_byte = (JOCTET*) tif->tif_rawdata;
    sp->dest.free_in_buffer = (size_t) tif->tif_rawdatasize;
}

static boolean
std_empty_output_buffer(j_compress_ptr cinfo)
{
    JPEGState* sp = (JPEGState*) cinfo;
    TIFF* tif = sp->tif;

    /* the entire buffer has been filled */
    tif->tif_rawcc = tif->tif_rawdatasize;
    TIFFFlushData1(tif);
    sp->dest.next_output_byte = (JOCTET*) tif->tif_rawdata;
    sp->dest.free_in_buffer = (size_t) tif->tif_rawdatasize;

    return (TRUE);
}

static void
std_term_destination(j_compress_ptr cinfo)
{
    JPEGState* sp = (JPEGState*) cinfo;
    TIFF* tif = sp->tif;

    tif->tif_rawcp = (tidata_t) sp->dest.next_output_byte;
    tif->tif_rawcc =
        tif->tif_rawdatasize - (tsize_t) sp->dest.free_in_buffer;
    /* NB: libtiff does the final buffer flush */
}

static void
TIFFjpeg_data_dest(JPEGState* sp, TIFF* tif)
{
    (void) tif;
    sp->cinfo.c.dest = &sp->dest;
    sp->dest.init_destination = std_init_destination;
    sp->dest.empty_output_buffer = std_empty_output_buffer;
    sp->dest.term_destination = std_term_destination;
}

/*
 * Alternate destination manager for outputting to JPEGTables field.
 */

static void
tables_init_destination(j_compress_ptr cinfo)
{
    JPEGState* sp = (JPEGState*) cinfo;

    /* while building, jpegtables_length is allocated buffer size */
    sp->dest.next_output_byte = (JOCTET*) sp->jpegtables;
    sp->dest.free_in_buffer = (size_t) sp->jpegtables_length;
}

static boolean
tables_empty_output_buffer(j_compress_ptr cinfo)
{
    JPEGState* sp = (JPEGState*) cinfo;
    void* newbuf;

    /* the entire buffer has been filled; enlarge it by 1000 bytes */
    newbuf = _TIFFrealloc((tdata_t) sp->jpegtables,
                  (tsize_t) (sp->jpegtables_length + 1000));
    if (newbuf == NULL)
        ERREXIT1(cinfo, JERR_OUT_OF_MEMORY, 100);
    sp->dest.next_output_byte = (JOCTET*) newbuf + sp->jpegtables_length;
    sp->dest.free_in_buffer = (size_t) 1000;
    sp->jpegtables = newbuf;
    sp->jpegtables_length += 1000;
    return (TRUE);
}

static void
tables_term_destination(j_compress_ptr cinfo)
{
    JPEGState* sp = (JPEGState*) cinfo;

    /* set tables length to number of bytes actually emitted */
    sp->jpegtables_length -= sp->dest.free_in_buffer;
}

static int
TIFFjpeg_tables_dest(JPEGState* sp, TIFF* tif)
{
    (void) tif;
    /*
     * Allocate a working buffer for building tables.
     * Initial size is 1000 bytes, which is usually adequate.
     */
    if (sp->jpegtables)
        _TIFFfree(sp->jpegtables);
    sp->jpegtables_length = 1000;
    sp->jpegtables = (void*) _TIFFmalloc((tsize_t) sp->jpegtables_length);
    if (sp->jpegtables == NULL) {
        sp->jpegtables_length = 0;
        TIFFErrorExt(sp->tif->tif_clientdata, "TIFFjpeg_tables_dest", "No space for JPEGTables");
        return (0);
    }
    sp->cinfo.c.dest = &sp->dest;
    sp->dest.init_destination = tables_init_destination;
    sp->dest.empty_output_buffer = tables_empty_output_buffer;
    sp->dest.term_destination = tables_term_destination;
    return (1);
}

/*
 * JPEG library source data manager.
 * These routines supply compressed data to libjpeg.
 */

static void
std_init_source(j_decompress_ptr cinfo)
{
    JPEGState* sp = (JPEGState*) cinfo;
    TIFF* tif = sp->tif;

    sp->src.next_input_byte = (const JOCTET*) tif->tif_rawdata;
    sp->src.bytes_in_buffer = (size_t) tif->tif_rawcc;
}

static boolean
std_fill_input_buffer(j_decompress_ptr cinfo)
{
    JPEGState* sp = (JPEGState* ) cinfo;
    static const JOCTET dummy_EOI[2] = { 0xFF, JPEG_EOI };

    /*
     * Should never get here since entire strip/tile is
     * read into memory before the decompressor is called,
     * and thus was supplied by init_source.
     */
    WARNMS(cinfo, JWRN_JPEG_EOF);
    /* insert a fake EOI marker */
    sp->src.next_input_byte = dummy_EOI;
    sp->src.bytes_in_buffer = 2;
    return (TRUE);
}

static void
std_skip_input_data(j_decompress_ptr cinfo, long num_bytes)
{
    JPEGState* sp = (JPEGState*) cinfo;

    if (num_bytes > 0) {
        if (num_bytes > (long) sp->src.bytes_in_buffer) {
            /* oops, buffer overrun */
            (void) std_fill_input_buffer(cinfo);
        } else {
            sp->src.next_input_byte += (size_t) num_bytes;
            sp->src.bytes_in_buffer -= (size_t) num_bytes;
        }
    }
}

static void
std_term_source(j_decompress_ptr cinfo)
{
    /* No work necessary here */
    /* Or must we update tif->tif_rawcp, tif->tif_rawcc ??? */
    /* (if so, need empty tables_term_source!) */
    (void) cinfo;
}

static void
TIFFjpeg_data_src(JPEGState* sp, TIFF* tif)
{
    (void) tif;
    sp->cinfo.d.src = &sp->src;
    sp->src.init_source = std_init_source;
    sp->src.fill_input_buffer = std_fill_input_buffer;
    sp->src.skip_input_data = std_skip_input_data;
    sp->src.resync_to_restart = jpeg_resync_to_restart;
    sp->src.term_source = std_term_source;
    sp->src.bytes_in_buffer = 0;        /* for safety */
    sp->src.next_input_byte = NULL;
}

/*
 * Alternate source manager for reading from JPEGTables.
 * We can share all the code except for the init routine.
 */

static void
tables_init_source(j_decompress_ptr cinfo)
{
    JPEGState* sp = (JPEGState*) cinfo;

    sp->src.next_input_byte = (const JOCTET*) sp->jpegtables;
    sp->src.bytes_in_buffer = (size_t) sp->jpegtables_length;
}

static void
TIFFjpeg_tables_src(JPEGState* sp, TIFF* tif)
{
    TIFFjpeg_data_src(sp, tif);
    sp->src.init_source = tables_init_source;
}

/*
 * Allocate downsampled-data buffers needed for downsampled I/O.
 * We use values computed in jpeg_start_compress or jpeg_start_decompress.
 * We use libjpeg's allocator so that buffers will be released automatically
 * when done with strip/tile.
 * This is also a handy place to compute samplesperclump, bytesperline.
 */
static int
alloc_downsampled_buffers(TIFF* tif, jpeg_component_info* comp_info,
              int num_components)
{
    JPEGState* sp = JState(tif);
    int ci;
    jpeg_component_info* compptr;
    JSAMPARRAY buf;
    int samples_per_clump = 0;

    for (ci = 0, compptr = comp_info; ci < num_components;
         ci++, compptr++) {
        samples_per_clump += compptr->h_samp_factor *
            compptr->v_samp_factor;
        buf = TIFFjpeg_alloc_sarray(sp, JPOOL_IMAGE,
                compptr->width_in_blocks * DCTSIZE,
                (JDIMENSION) (compptr->v_samp_factor*DCTSIZE));
        if (buf == NULL)
            return (0);
        sp->ds_buffer[ci] = buf;
    }
    sp->samplesperclump = samples_per_clump;
    return (1);
}


/*
 * JPEG Decoding.
 */

static int
JPEGSetupDecode(TIFF* tif)
{
    JPEGState* sp = JState(tif);
    TIFFDirectory *td = &tif->tif_dir;

        JPEGInitializeLibJPEG( tif, 0, 1 );

    assert(sp != NULL);
    assert(sp->cinfo.comm.is_decompressor);

    /* Read JPEGTables if it is present */
    if (TIFFFieldSet(tif,FIELD_JPEGTABLES)) {
        TIFFjpeg_tables_src(sp, tif);
        if(TIFFjpeg_read_header(sp,FALSE) != JPEG_HEADER_TABLES_ONLY) {
            TIFFErrorExt(tif->tif_clientdata, "JPEGSetupDecode", "Bogus JPEGTables field");
            return (0);
        }
    }

    /* Grab parameters that are same for all strips/tiles */
    sp->photometric = td->td_photometric;
    switch (sp->photometric) {
    case PHOTOMETRIC_YCBCR:
        sp->h_sampling = td->td_ycbcrsubsampling[0];
        sp->v_sampling = td->td_ycbcrsubsampling[1];
        break;
    default:
        /* TIFF 6.0 forbids subsampling of all other color spaces */
        sp->h_sampling = 1;
        sp->v_sampling = 1;
        break;
    }

    /* Set up for reading normal data */
    TIFFjpeg_data_src(sp, tif);
    tif->tif_postdecode = _TIFFNoPostDecode; /* override byte swapping */
    return (1);
}

/*
 * Set up for decoding a strip or tile.
 */
static int
JPEGPreDecode(TIFF* tif, tsample_t s)
{
    JPEGState *sp = JState(tif);
    TIFFDirectory *td = &tif->tif_dir;
    static const char module[] = "JPEGPreDecode";
    uint32 segment_width, segment_height;
    int downsampled_output;
    int ci;

    assert(sp != NULL);
    assert(sp->cinfo.comm.is_decompressor);
    /*
     * Reset decoder state from any previous strip/tile,
     * in case application didn't read the whole strip.
     */
    if (!TIFFjpeg_abort(sp))
        return (0);
    /*
     * Read the header for this strip/tile.
     */
    if (TIFFjpeg_read_header(sp, TRUE) != JPEG_HEADER_OK)
        return (0);
    /*
     * Check image parameters and set decompression parameters.
     */
    segment_width = td->td_imagewidth;
    segment_height = td->td_imagelength - tif->tif_row;
    if (isTiled(tif)) {
                segment_width = td->td_tilewidth;
                segment_height = td->td_tilelength;
        sp->bytesperline = TIFFTileRowSize(tif);
    } else {
        if (segment_height > td->td_rowsperstrip)
            segment_height = td->td_rowsperstrip;
        sp->bytesperline = TIFFOldScanlineSize(tif);
    }
    if (td->td_planarconfig == PLANARCONFIG_SEPARATE && s > 0) {
        /*
         * For PC 2, scale down the expected strip/tile size
         * to match a downsampled component
         */
        segment_width = TIFFhowmany(segment_width, sp->h_sampling);
        segment_height = TIFFhowmany(segment_height, sp->v_sampling);
    }
    if (sp->cinfo.d.image_width < segment_width ||
        sp->cinfo.d.image_height < segment_height) {
        TIFFWarningExt(tif->tif_clientdata, module,
                   "Improper JPEG strip/tile size, "
                   "expected %dx%d, got %dx%d",
                   segment_width, segment_height,
                   sp->cinfo.d.image_width,
                   sp->cinfo.d.image_height);
    } 
    if (sp->cinfo.d.image_width > segment_width ||
        sp->cinfo.d.image_height > segment_height) {
        /*
         * This case could be dangerous, if the strip or tile size has
         * been reported as less than the amount of data jpeg will
         * return, some potential security issues arise. Catch this
         * case and error out.
         */
        TIFFErrorExt(tif->tif_clientdata, module,
                 "JPEG strip/tile size exceeds expected dimensions,"
                 " expected %dx%d, got %dx%d",
                 segment_width, segment_height,
                 sp->cinfo.d.image_width, sp->cinfo.d.image_height);
        return (0);
    }
    if (sp->cinfo.d.num_components !=
        (td->td_planarconfig == PLANARCONFIG_CONTIG ?
         td->td_samplesperpixel : 1)) {
        TIFFErrorExt(tif->tif_clientdata, module, "Improper JPEG component count");
        return (0);
    }
#ifdef JPEG_LIB_MK1
    if (12 != td->td_bitspersample && 8 != td->td_bitspersample) {
            TIFFErrorExt(tif->tif_clientdata, module, "Improper JPEG data precision");
            return (0);
    }
        sp->cinfo.d.data_precision = td->td_bitspersample;
        sp->cinfo.d.bits_in_jsample = td->td_bitspersample;
#else
    if (sp->cinfo.d.data_precision != td->td_bitspersample) {
            TIFFErrorExt(tif->tif_clientdata, module, "Improper JPEG data precision");
            return (0);
    }
#endif
    if (td->td_planarconfig == PLANARCONFIG_CONTIG) {
        /* Component 0 should have expected sampling factors */
        if (sp->cinfo.d.comp_info[0].h_samp_factor != sp->h_sampling ||
            sp->cinfo.d.comp_info[0].v_samp_factor != sp->v_sampling) {
                TIFFWarningExt(tif->tif_clientdata, module,
                                    "Improper JPEG sampling factors %d,%d\n"
                                    "Apparently should be %d,%d.",
                                    sp->cinfo.d.comp_info[0].h_samp_factor,
                                    sp->cinfo.d.comp_info[0].v_samp_factor,
                                    sp->h_sampling, sp->v_sampling);

                /*
                 * There are potential security issues here
                 * for decoders that have already allocated
                 * buffers based on the expected sampling
                 * factors. Lets check the sampling factors
                 * dont exceed what we were expecting.
                 */
                if (sp->cinfo.d.comp_info[0].h_samp_factor
                    > sp->h_sampling
                    || sp->cinfo.d.comp_info[0].v_samp_factor
                    > sp->v_sampling) {
                    TIFFErrorExt(tif->tif_clientdata,
                             module,
                    "Cannot honour JPEG sampling factors"
                    " that exceed those specified.");
                    return (0);
                }

                /*
                 * XXX: Files written by the Intergraph software
                 * has different sampling factors stored in the
                 * TIFF tags and in the JPEG structures. We will
                 * try to deduce Intergraph files by the presense
                 * of the tag 33918.
                 */
                if (!_TIFFFindFieldInfo(tif, 33918, TIFF_ANY)) {
                    TIFFWarningExt(tif->tif_clientdata, module,
                    "Decompressor will try reading with "
                    "sampling %d,%d.",
                    sp->cinfo.d.comp_info[0].h_samp_factor,
                    sp->cinfo.d.comp_info[0].v_samp_factor);

                    sp->h_sampling = (uint16)
                    sp->cinfo.d.comp_info[0].h_samp_factor;
                    sp->v_sampling = (uint16)
                    sp->cinfo.d.comp_info[0].v_samp_factor;
                }
        }
        /* Rest should have sampling factors 1,1 */
        for (ci = 1; ci < sp->cinfo.d.num_components; ci++) {
            if (sp->cinfo.d.comp_info[ci].h_samp_factor != 1 ||
                sp->cinfo.d.comp_info[ci].v_samp_factor != 1) {
                TIFFErrorExt(tif->tif_clientdata, module, "Improper JPEG sampling factors");
                return (0);
            }
        }
    } else {
        /* PC 2's single component should have sampling factors 1,1 */
        if (sp->cinfo.d.comp_info[0].h_samp_factor != 1 ||
            sp->cinfo.d.comp_info[0].v_samp_factor != 1) {
            TIFFErrorExt(tif->tif_clientdata, module, "Improper JPEG sampling factors");
            return (0);
        }
    }
    downsampled_output = FALSE;
    if (td->td_planarconfig == PLANARCONFIG_CONTIG &&
        sp->photometric == PHOTOMETRIC_YCBCR &&
        sp->jpegcolormode == JPEGCOLORMODE_RGB) {
    /* Convert YCbCr to RGB */
        sp->cinfo.d.jpeg_color_space = JCS_YCbCr;
        sp->cinfo.d.out_color_space = JCS_RGB;
    } else {
            /* Suppress colorspace handling */
        sp->cinfo.d.jpeg_color_space = JCS_UNKNOWN;
        sp->cinfo.d.out_color_space = JCS_UNKNOWN;
        if (td->td_planarconfig == PLANARCONFIG_CONTIG &&
            (sp->h_sampling != 1 || sp->v_sampling != 1))
            downsampled_output = TRUE;
        /* XXX what about up-sampling? */
    }
    if (downsampled_output) {
        /* Need to use raw-data interface to libjpeg */
        sp->cinfo.d.raw_data_out = TRUE;
        tif->tif_decoderow = JPEGDecodeRaw;
        tif->tif_decodestrip = JPEGDecodeRaw;
        tif->tif_decodetile = JPEGDecodeRaw;
    } else {
        /* Use normal interface to libjpeg */
        sp->cinfo.d.raw_data_out = FALSE;
        tif->tif_decoderow = JPEGDecode;
        tif->tif_decodestrip = JPEGDecode;
        tif->tif_decodetile = JPEGDecode;
    }
    /* Start JPEG decompressor */
    if (!TIFFjpeg_start_decompress(sp))
        return (0);
    /* Allocate downsampled-data buffers if needed */
    if (downsampled_output) {
        if (!alloc_downsampled_buffers(tif, sp->cinfo.d.comp_info,
                           sp->cinfo.d.num_components))
            return (0);
        sp->scancount = DCTSIZE;    /* mark buffer empty */
    }
    return (1);
}

/*
 * Decode a chunk of pixels.
 * "Standard" case: returned data is not downsampled.
 */
/*ARGSUSED*/ static int
JPEGDecode(TIFF* tif, tidata_t buf, tsize_t cc, tsample_t s)
{
    JPEGState *sp = JState(tif);
    tsize_t nrows;
    (void) s;

    nrows = cc / sp->bytesperline;
    if (cc % sp->bytesperline)
        TIFFWarningExt(tif->tif_clientdata, tif->tif_name, "fractional scanline not read");

    if( nrows > (int) sp->cinfo.d.image_height )
        nrows = sp->cinfo.d.image_height;

    /* data is expected to be read in multiples of a scanline */
    if (nrows)
    {
        JSAMPROW line_work_buf = NULL;

        /*
        ** For 6B, only use temporary buffer for 12 bit imagery. 
        ** For Mk1 always use it. 
        */
#if !defined(JPEG_LIB_MK1)        
        if( sp->cinfo.d.data_precision == 12 )
#endif
        {
            line_work_buf = (JSAMPROW) 
                _TIFFmalloc(sizeof(short) * sp->cinfo.d.output_width 
                            * sp->cinfo.d.num_components );
        }

        do {
            if( line_work_buf != NULL )
            {
                /* 
                ** In the MK1 case, we aways read into a 16bit buffer, and then
                ** pack down to 12bit or 8bit.  In 6B case we only read into 16
                ** bit buffer for 12bit data, which we need to repack. 
                */
                if (TIFFjpeg_read_scanlines(sp, &line_work_buf, 1) != 1)
                    return (0);

                if( sp->cinfo.d.data_precision == 12 )
                {
                    int value_pairs = (sp->cinfo.d.output_width 
                                       * sp->cinfo.d.num_components) / 2;
                    int iPair;

                    for( iPair = 0; iPair < value_pairs; iPair++ )
                    {
                        unsigned char *out_ptr = 
                            ((unsigned char *) buf) + iPair * 3;
                        JSAMPLE *in_ptr = line_work_buf + iPair * 2;

                        out_ptr[0] = (in_ptr[0] & 0xff0) >> 4;
                        out_ptr[1] = ((in_ptr[0] & 0xf) << 4)
                            | ((in_ptr[1] & 0xf00) >> 8);
                        out_ptr[2] = ((in_ptr[1] & 0xff) >> 0);
                    }
                }
                else if( sp->cinfo.d.data_precision == 8 )
                {
                    int value_count = (sp->cinfo.d.output_width 
                                       * sp->cinfo.d.num_components);
                    int iValue;

                    for( iValue = 0; iValue < value_count; iValue++ )
                    {
                        ((unsigned char *) buf)[iValue] = 
                            line_work_buf[iValue] & 0xff;
                    }
                }
            }
            else
            {
                /*
                ** In the libjpeg6b 8bit case.  We read directly into the 
                ** TIFF buffer.
                */
                JSAMPROW bufptr = (JSAMPROW)buf;
  
                if (TIFFjpeg_read_scanlines(sp, &bufptr, 1) != 1)
                    return (0);
            }

            ++tif->tif_row;
            buf += sp->bytesperline;
            cc -= sp->bytesperline;
        } while (--nrows > 0);

        if( line_work_buf != NULL )
            _TIFFfree( line_work_buf );
    }

    /* Close down the decompressor if we've finished the strip or tile. */
    return sp->cinfo.d.output_scanline < sp->cinfo.d.output_height
        || TIFFjpeg_finish_decompress(sp);
}

/*
 * Decode a chunk of pixels.
 * Returned data is downsampled per sampling factors.
 */
/*ARGSUSED*/ static int
JPEGDecodeRaw(TIFF* tif, tidata_t buf, tsize_t cc, tsample_t s)
{
    JPEGState *sp = JState(tif);
    tsize_t nrows;
    (void) s;

    /* data is expected to be read in multiples of a scanline */
    if ( (nrows = sp->cinfo.d.image_height) ) {
        /* Cb,Cr both have sampling factors 1, so this is correct */
        JDIMENSION clumps_per_line = sp->cinfo.d.comp_info[1].downsampled_width;            
        int samples_per_clump = sp->samplesperclump;

#ifdef JPEG_LIB_MK1
        unsigned short* tmpbuf = _TIFFmalloc(sizeof(unsigned short) *
            sp->cinfo.d.output_width *
            sp->cinfo.d.num_components);
#endif

        do {
            jpeg_component_info *compptr;
            int ci, clumpoffset;

            /* Reload downsampled-data buffer if needed */
            if (sp->scancount >= DCTSIZE) {
                int n = sp->cinfo.d.max_v_samp_factor * DCTSIZE;
                if (TIFFjpeg_read_raw_data(sp, sp->ds_buffer, n) != n)
                    return (0);
                sp->scancount = 0;
            }
            /*
             * Fastest way to unseparate data is to make one pass
             * over the scanline for each row of each component.
             */
            clumpoffset = 0;    /* first sample in clump */
            for (ci = 0, compptr = sp->cinfo.d.comp_info;
                ci < sp->cinfo.d.num_components;
                ci++, compptr++) {
                int hsamp = compptr->h_samp_factor;
                int vsamp = compptr->v_samp_factor;
                int ypos;

                for (ypos = 0; ypos < vsamp; ypos++) {
                    JSAMPLE *inptr = sp->ds_buffer[ci][sp->scancount*vsamp + ypos];
#ifdef JPEG_LIB_MK1
                    JSAMPLE *outptr = (JSAMPLE*)tmpbuf + clumpoffset;
#else
                    JSAMPLE *outptr = (JSAMPLE*)buf + clumpoffset;
#endif
                    JDIMENSION nclump;

                    if (hsamp == 1) {
                        /* fast path for at least Cb and Cr */
                        for (nclump = clumps_per_line; nclump-- > 0; ) {
                            outptr[0] = *inptr++;
                            outptr += samples_per_clump;
                        }
                    } else {
                        int xpos;

            /* general case */
                        for (nclump = clumps_per_line; nclump-- > 0; ) {
                            for (xpos = 0; xpos < hsamp; xpos++)
                                outptr[xpos] = *inptr++;
                            outptr += samples_per_clump;
                        }
                    }
                    clumpoffset += hsamp;
                }
            }

#ifdef JPEG_LIB_MK1
            {
                if (sp->cinfo.d.data_precision == 8)
                {
                    int i=0;
                    int len = sp->cinfo.d.output_width * sp->cinfo.d.num_components;
                    for (i=0; i<len; i++)
                    {
                        ((unsigned char*)buf)[i] = tmpbuf[i] & 0xff;
                    }
                }
                else
                {         // 12-bit
                    int value_pairs = (sp->cinfo.d.output_width
                        * sp->cinfo.d.num_components) / 2;
                    int iPair;
                    for( iPair = 0; iPair < value_pairs; iPair++ )
                    {
                        unsigned char *out_ptr = ((unsigned char *) buf) + iPair * 3;
                        JSAMPLE *in_ptr = tmpbuf + iPair * 2;
                        out_ptr[0] = (in_ptr[0] & 0xff0) >> 4;
                        out_ptr[1] = ((in_ptr[0] & 0xf) << 4)
                            | ((in_ptr[1] & 0xf00) >> 8);
                        out_ptr[2] = ((in_ptr[1] & 0xff) >> 0);
                    }
                }
            }
#endif

            sp->scancount ++;
            tif->tif_row += sp->v_sampling;
            /* increment/decrement of buf and cc is still incorrect, but should not matter
             * TODO: resolve this */
            buf += sp->bytesperline;
            cc -= sp->bytesperline;
            nrows -= sp->v_sampling;
        } while (nrows > 0);

#ifdef JPEG_LIB_MK1
        _TIFFfree(tmpbuf);
#endif

    }

    /* Close down the decompressor if done. */
    return sp->cinfo.d.output_scanline < sp->cinfo.d.output_height
        || TIFFjpeg_finish_decompress(sp);
}


/*
 * JPEG Encoding.
 */

static void
unsuppress_quant_table (JPEGState* sp, int tblno)
{
    JQUANT_TBL* qtbl;

    if ((qtbl = sp->cinfo.c.quant_tbl_ptrs[tblno]) != NULL)
        qtbl->sent_table = FALSE;
}

static void
unsuppress_huff_table (JPEGState* sp, int tblno)
{
    JHUFF_TBL* htbl;

    if ((htbl = sp->cinfo.c.dc_huff_tbl_ptrs[tblno]) != NULL)
        htbl->sent_table = FALSE;
    if ((htbl = sp->cinfo.c.ac_huff_tbl_ptrs[tblno]) != NULL)
        htbl->sent_table = FALSE;
}

static int
prepare_JPEGTables(TIFF* tif)
{
    JPEGState* sp = JState(tif);

        JPEGInitializeLibJPEG( tif, 0, 0 );

    /* Initialize quant tables for current quality setting */
    if (!TIFFjpeg_set_quality(sp, sp->jpegquality, FALSE))
        return (0);
    /* Mark only the tables we want for output */
    /* NB: chrominance tables are currently used only with YCbCr */
    if (!TIFFjpeg_suppress_tables(sp, TRUE))
        return (0);
    if (sp->jpegtablesmode & JPEGTABLESMODE_QUANT) {
        unsuppress_quant_table(sp, 0);
        if (sp->photometric == PHOTOMETRIC_YCBCR)
            unsuppress_quant_table(sp, 1);
    }
    if (sp->jpegtablesmode & JPEGTABLESMODE_HUFF) {
        unsuppress_huff_table(sp, 0);
        if (sp->photometric == PHOTOMETRIC_YCBCR)
            unsuppress_huff_table(sp, 1);
    }
    /* Direct libjpeg output into jpegtables */
    if (!TIFFjpeg_tables_dest(sp, tif))
        return (0);
    /* Emit tables-only datastream */
    if (!TIFFjpeg_write_tables(sp))
        return (0);

    return (1);
}

static int
JPEGSetupEncode(TIFF* tif)
{
    JPEGState* sp = JState(tif);
    TIFFDirectory *td = &tif->tif_dir;
    static const char module[] = "JPEGSetupEncode";

        JPEGInitializeLibJPEG( tif, 1, 0 );

    assert(sp != NULL);
    assert(!sp->cinfo.comm.is_decompressor);

    /*
     * Initialize all JPEG parameters to default values.
     * Note that jpeg_set_defaults needs legal values for
     * in_color_space and input_components.
     */
    sp->cinfo.c.in_color_space = JCS_UNKNOWN;
    sp->cinfo.c.input_components = 1;
    if (!TIFFjpeg_set_defaults(sp))
        return (0);
    /* Set per-file parameters */
    sp->photometric = td->td_photometric;
    switch (sp->photometric) {
    case PHOTOMETRIC_YCBCR:
        sp->h_sampling = td->td_ycbcrsubsampling[0];
        sp->v_sampling = td->td_ycbcrsubsampling[1];
        /*
         * A ReferenceBlackWhite field *must* be present since the
         * default value is inappropriate for YCbCr.  Fill in the
         * proper value if application didn't set it.
         */
        {
            float *ref;
            if (!TIFFGetField(tif, TIFFTAG_REFERENCEBLACKWHITE,
                      &ref)) {
                float refbw[6];
                long top = 1L << td->td_bitspersample;
                refbw[0] = 0;
                refbw[1] = (float)(top-1L);
                refbw[2] = (float)(top>>1);
                refbw[3] = refbw[1];
                refbw[4] = refbw[2];
                refbw[5] = refbw[1];
                TIFFSetField(tif, TIFFTAG_REFERENCEBLACKWHITE,
                         refbw);
            }
        }
        break;
    case PHOTOMETRIC_PALETTE:       /* disallowed by Tech Note */
    case PHOTOMETRIC_MASK:
        TIFFErrorExt(tif->tif_clientdata, module,
              "PhotometricInterpretation %d not allowed for JPEG",
              (int) sp->photometric);
        return (0);
    default:
        /* TIFF 6.0 forbids subsampling of all other color spaces */
        sp->h_sampling = 1;
        sp->v_sampling = 1;
        break;
    }

    /* Verify miscellaneous parameters */

    /*
     * This would need work if libtiff ever supports different
     * depths for different components, or if libjpeg ever supports
     * run-time selection of depth.  Neither is imminent.
     */
#ifdef JPEG_LIB_MK1
        /* BITS_IN_JSAMPLE now permits 8 and 12 --- dgilbert */
    if (td->td_bitspersample != 8 && td->td_bitspersample != 12) 
#else
    if (td->td_bitspersample != BITS_IN_JSAMPLE )
#endif
    {
        TIFFErrorExt(tif->tif_clientdata, module, "BitsPerSample %d not allowed for JPEG",
              (int) td->td_bitspersample);
        return (0);
    }
    sp->cinfo.c.data_precision = td->td_bitspersample;
#ifdef JPEG_LIB_MK1
        sp->cinfo.c.bits_in_jsample = td->td_bitspersample;
#endif
    if (isTiled(tif)) {
        if ((td->td_tilelength % (sp->v_sampling * DCTSIZE)) != 0) {
            TIFFErrorExt(tif->tif_clientdata, module,
                  "JPEG tile height must be multiple of %d",
                  sp->v_sampling * DCTSIZE);
            return (0);
        }
        if ((td->td_tilewidth % (sp->h_sampling * DCTSIZE)) != 0) {
            TIFFErrorExt(tif->tif_clientdata, module,
                  "JPEG tile width must be multiple of %d",
                  sp->h_sampling * DCTSIZE);
            return (0);
        }
    } else {
        if (td->td_rowsperstrip < td->td_imagelength &&
            (td->td_rowsperstrip % (sp->v_sampling * DCTSIZE)) != 0) {
            TIFFErrorExt(tif->tif_clientdata, module,
                  "RowsPerStrip must be multiple of %d for JPEG",
                  sp->v_sampling * DCTSIZE);
            return (0);
        }
    }

    /* Create a JPEGTables field if appropriate */
    if (sp->jpegtablesmode & (JPEGTABLESMODE_QUANT|JPEGTABLESMODE_HUFF)) {
                if( sp->jpegtables == NULL
                    || memcmp(sp->jpegtables,"\0\0\0\0\0\0\0\0\0",8) == 0 )
                {
                        if (!prepare_JPEGTables(tif))
                                return (0);
                        /* Mark the field present */
                        /* Can't use TIFFSetField since BEENWRITING is already set! */
                        tif->tif_flags |= TIFF_DIRTYDIRECT;
                        TIFFSetFieldBit(tif, FIELD_JPEGTABLES);
                }
    } else {
        /* We do not support application-supplied JPEGTables, */
        /* so mark the field not present */
        TIFFClrFieldBit(tif, FIELD_JPEGTABLES);
    }

    /* Direct libjpeg output to libtiff's output buffer */
    TIFFjpeg_data_dest(sp, tif);

    return (1);
}

/*
 * Set encoding state at the start of a strip or tile.
 */
static int
JPEGPreEncode(TIFF* tif, tsample_t s)
{
    JPEGState *sp = JState(tif);
    TIFFDirectory *td = &tif->tif_dir;
    static const char module[] = "JPEGPreEncode";
    uint32 segment_width, segment_height;
    int downsampled_input;

    assert(sp != NULL);
    assert(!sp->cinfo.comm.is_decompressor);
    /*
     * Set encoding parameters for this strip/tile.
     */
    if (isTiled(tif)) {
        segment_width = td->td_tilewidth;
        segment_height = td->td_tilelength;
        sp->bytesperline = TIFFTileRowSize(tif);
    } else {
        segment_width = td->td_imagewidth;
        segment_height = td->td_imagelength - tif->tif_row;
        if (segment_height > td->td_rowsperstrip)
            segment_height = td->td_rowsperstrip;
        sp->bytesperline = TIFFOldScanlineSize(tif);
    }
    if (td->td_planarconfig == PLANARCONFIG_SEPARATE && s > 0) {
        /* for PC 2, scale down the strip/tile size
         * to match a downsampled component
         */
        segment_width = TIFFhowmany(segment_width, sp->h_sampling);
        segment_height = TIFFhowmany(segment_height, sp->v_sampling);
    }
    if (segment_width > 65535 || segment_height > 65535) {
        TIFFErrorExt(tif->tif_clientdata, module, "Strip/tile too large for JPEG");
        return (0);
    }
    sp->cinfo.c.image_width = segment_width;
    sp->cinfo.c.image_height = segment_height;
    downsampled_input = FALSE;
    if (td->td_planarconfig == PLANARCONFIG_CONTIG) {
        sp->cinfo.c.input_components = td->td_samplesperpixel;
        if (sp->photometric == PHOTOMETRIC_YCBCR) {
            if (sp->jpegcolormode == JPEGCOLORMODE_RGB) {
                sp->cinfo.c.in_color_space = JCS_RGB;
            } else {
                sp->cinfo.c.in_color_space = JCS_YCbCr;
                if (sp->h_sampling != 1 || sp->v_sampling != 1)
                    downsampled_input = TRUE;
            }
            if (!TIFFjpeg_set_colorspace(sp, JCS_YCbCr))
                return (0);
            /*
             * Set Y sampling factors;
             * we assume jpeg_set_colorspace() set the rest to 1
             */
            sp->cinfo.c.comp_info[0].h_samp_factor = sp->h_sampling;
            sp->cinfo.c.comp_info[0].v_samp_factor = sp->v_sampling;
        } else {
            sp->cinfo.c.in_color_space = JCS_UNKNOWN;
            if (!TIFFjpeg_set_colorspace(sp, JCS_UNKNOWN))
                return (0);
            /* jpeg_set_colorspace set all sampling factors to 1 */
        }
    } else {
        sp->cinfo.c.input_components = 1;
        sp->cinfo.c.in_color_space = JCS_UNKNOWN;
        if (!TIFFjpeg_set_colorspace(sp, JCS_UNKNOWN))
            return (0);
        sp->cinfo.c.comp_info[0].component_id = s;
        /* jpeg_set_colorspace() set sampling factors to 1 */
        if (sp->photometric == PHOTOMETRIC_YCBCR && s > 0) {
            sp->cinfo.c.comp_info[0].quant_tbl_no = 1;
            sp->cinfo.c.comp_info[0].dc_tbl_no = 1;
            sp->cinfo.c.comp_info[0].ac_tbl_no = 1;
        }
    }
    /* ensure libjpeg won't write any extraneous markers */
    sp->cinfo.c.write_JFIF_header = FALSE;
    sp->cinfo.c.write_Adobe_marker = FALSE;
    /* set up table handling correctly */
        if (!TIFFjpeg_set_quality(sp, sp->jpegquality, FALSE))
                return (0);
    if (! (sp->jpegtablesmode & JPEGTABLESMODE_QUANT)) {
        unsuppress_quant_table(sp, 0);
        unsuppress_quant_table(sp, 1);
    }
    if (sp->jpegtablesmode & JPEGTABLESMODE_HUFF)
        sp->cinfo.c.optimize_coding = FALSE;
    else
        sp->cinfo.c.optimize_coding = TRUE;
    if (downsampled_input) {
        /* Need to use raw-data interface to libjpeg */
        sp->cinfo.c.raw_data_in = TRUE;
        tif->tif_encoderow = JPEGEncodeRaw;
        tif->tif_encodestrip = JPEGEncodeRaw;
        tif->tif_encodetile = JPEGEncodeRaw;
    } else {
        /* Use normal interface to libjpeg */
        sp->cinfo.c.raw_data_in = FALSE;
        tif->tif_encoderow = JPEGEncode;
        tif->tif_encodestrip = JPEGEncode;
        tif->tif_encodetile = JPEGEncode;
    }
    /* Start JPEG compressor */
    if (!TIFFjpeg_start_compress(sp, FALSE))
        return (0);
    /* Allocate downsampled-data buffers if needed */
    if (downsampled_input) {
        if (!alloc_downsampled_buffers(tif, sp->cinfo.c.comp_info,
                           sp->cinfo.c.num_components))
            return (0);
    }
    sp->scancount = 0;

    return (1);
}

/*
 * Encode a chunk of pixels.
 * "Standard" case: incoming data is not downsampled.
 */
static int
JPEGEncode(TIFF* tif, tidata_t buf, tsize_t cc, tsample_t s)
{
    JPEGState *sp = JState(tif);
    tsize_t nrows;
    JSAMPROW bufptr[1];

    (void) s;
    assert(sp != NULL);
    /* data is expected to be supplied in multiples of a scanline */
    nrows = cc / sp->bytesperline;
    if (cc % sp->bytesperline)
        TIFFWarningExt(tif->tif_clientdata, tif->tif_name, "fractional scanline discarded");

        /* The last strip will be limited to image size */
        if( !isTiled(tif) && tif->tif_row+nrows > tif->tif_dir.td_imagelength )
            nrows = tif->tif_dir.td_imagelength - tif->tif_row;

    while (nrows-- > 0) {
        bufptr[0] = (JSAMPROW) buf;
        if (TIFFjpeg_write_scanlines(sp, bufptr, 1) != 1)
            return (0);
        if (nrows > 0)
            tif->tif_row++;
        buf += sp->bytesperline;
    }
    return (1);
}

/*
 * Encode a chunk of pixels.
 * Incoming data is expected to be downsampled per sampling factors.
 */
static int
JPEGEncodeRaw(TIFF* tif, tidata_t buf, tsize_t cc, tsample_t s)
{
    JPEGState *sp = JState(tif);
    JSAMPLE* inptr;
    JSAMPLE* outptr;
    tsize_t nrows;
    JDIMENSION clumps_per_line, nclump;
    int clumpoffset, ci, xpos, ypos;
    jpeg_component_info* compptr;
    int samples_per_clump = sp->samplesperclump;
    tsize_t bytesperclumpline;

    (void) s;
    assert(sp != NULL);
    /* data is expected to be supplied in multiples of a clumpline */
    /* a clumpline is equivalent to v_sampling desubsampled scanlines */
    /* TODO: the following calculation of bytesperclumpline, should substitute calculation of sp->bytesperline, except that it is per v_sampling lines */
    bytesperclumpline = (((sp->cinfo.c.image_width+sp->h_sampling-1)/sp->h_sampling)
                 *(sp->h_sampling*sp->v_sampling+2)*sp->cinfo.c.data_precision+7)
                /8;

    nrows = ( cc / bytesperclumpline ) * sp->v_sampling;
    if (cc % bytesperclumpline)
        TIFFWarningExt(tif->tif_clientdata, tif->tif_name, "fractional scanline discarded");

    /* Cb,Cr both have sampling factors 1, so this is correct */
    clumps_per_line = sp->cinfo.c.comp_info[1].downsampled_width;

    while (nrows > 0) {
        /*
         * Fastest way to separate the data is to make one pass
         * over the scanline for each row of each component.
         */
        clumpoffset = 0;        /* first sample in clump */
        for (ci = 0, compptr = sp->cinfo.c.comp_info;
             ci < sp->cinfo.c.num_components;
             ci++, compptr++) {
            int hsamp = compptr->h_samp_factor;
            int vsamp = compptr->v_samp_factor;
            int padding = (int) (compptr->width_in_blocks * DCTSIZE -
                     clumps_per_line * hsamp);
            for (ypos = 0; ypos < vsamp; ypos++) {
            inptr = ((JSAMPLE*) buf) + clumpoffset;
            outptr = sp->ds_buffer[ci][sp->scancount*vsamp + ypos];
            if (hsamp == 1) {
                /* fast path for at least Cb and Cr */
                for (nclump = clumps_per_line; nclump-- > 0; ) {
                *outptr++ = inptr[0];
                inptr += samples_per_clump;
                }
            } else {
                /* general case */
                for (nclump = clumps_per_line; nclump-- > 0; ) {
                for (xpos = 0; xpos < hsamp; xpos++)
                    *outptr++ = inptr[xpos];
                inptr += samples_per_clump;
                }
            }
            /* pad each scanline as needed */
            for (xpos = 0; xpos < padding; xpos++) {
                *outptr = outptr[-1];
                outptr++;
            }
            clumpoffset += hsamp;
            }
        }
        sp->scancount++;
        if (sp->scancount >= DCTSIZE) {
            int n = sp->cinfo.c.max_v_samp_factor * DCTSIZE;
            if (TIFFjpeg_write_raw_data(sp, sp->ds_buffer, n) != n)
                return (0);
            sp->scancount = 0;
        }
        tif->tif_row += sp->v_sampling;
        buf += sp->bytesperline;
        nrows -= sp->v_sampling;
    }
    return (1);
}

/*
 * Finish up at the end of a strip or tile.
 */
static int
JPEGPostEncode(TIFF* tif)
{
    JPEGState *sp = JState(tif);

    if (sp->scancount > 0) {
        /*
         * Need to emit a partial bufferload of downsampled data.
         * Pad the data vertically.
         */
        int ci, ypos, n;
        jpeg_component_info* compptr;

        for (ci = 0, compptr = sp->cinfo.c.comp_info;
             ci < sp->cinfo.c.num_components;
             ci++, compptr++) {
            int vsamp = compptr->v_samp_factor;
            tsize_t row_width = compptr->width_in_blocks * DCTSIZE
                * sizeof(JSAMPLE);
            for (ypos = sp->scancount * vsamp;
                 ypos < DCTSIZE * vsamp; ypos++) {
                _TIFFmemcpy((tdata_t)sp->ds_buffer[ci][ypos],
                        (tdata_t)sp->ds_buffer[ci][ypos-1],
                        row_width);

            }
        }
        n = sp->cinfo.c.max_v_samp_factor * DCTSIZE;
        if (TIFFjpeg_write_raw_data(sp, sp->ds_buffer, n) != n)
            return (0);
    }

    return (TIFFjpeg_finish_compress(JState(tif)));
}

static void
JPEGCleanup(TIFF* tif)
{
    JPEGState *sp = JState(tif);
    
    assert(sp != 0);

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

    if( sp->cinfo_initialized )
        TIFFjpeg_destroy(sp);   /* release libjpeg resources */
    if (sp->jpegtables)     /* tag value */
        _TIFFfree(sp->jpegtables);
    _TIFFfree(tif->tif_data);   /* release local state */
    tif->tif_data = NULL;

    _TIFFSetDefaultCompressionState(tif);
}

static void 
JPEGResetUpsampled( TIFF* tif )
{
    JPEGState* sp = JState(tif);
    TIFFDirectory* td = &tif->tif_dir;

    /*
     * Mark whether returned data is up-sampled or not so TIFFStripSize
     * and TIFFTileSize return values that reflect the true amount of
     * data.
     */
    tif->tif_flags &= ~TIFF_UPSAMPLED;
    if (td->td_planarconfig == PLANARCONFIG_CONTIG) {
        if (td->td_photometric == PHOTOMETRIC_YCBCR &&
            sp->jpegcolormode == JPEGCOLORMODE_RGB) {
            tif->tif_flags |= TIFF_UPSAMPLED;
        } else {
#ifdef notdef
            if (td->td_ycbcrsubsampling[0] != 1 ||
                td->td_ycbcrsubsampling[1] != 1)
                ; /* XXX what about up-sampling? */
#endif
        }
    }

    /*
     * Must recalculate cached tile size in case sampling state changed.
     * Should we really be doing this now if image size isn't set? 
     */
        if( tif->tif_tilesize > 0 )
            tif->tif_tilesize = isTiled(tif) ? TIFFTileSize(tif) : (tsize_t) -1;

        if(tif->tif_scanlinesize > 0 )
            tif->tif_scanlinesize = TIFFScanlineSize(tif); 
}

static int
JPEGVSetField(TIFF* tif, ttag_t tag, va_list ap)
{
    JPEGState* sp = JState(tif);
    const TIFFFieldInfo* fip;
    uint32 v32;

    assert(sp != NULL);

    switch (tag) {
    case TIFFTAG_JPEGTABLES:
        v32 = va_arg(ap, uint32);
        if (v32 == 0) {
            /* XXX */
            return (0);
        }
        _TIFFsetByteArray(&sp->jpegtables, va_arg(ap, void*),
            (long) v32);
        sp->jpegtables_length = v32;
        TIFFSetFieldBit(tif, FIELD_JPEGTABLES);
        break;
    case TIFFTAG_JPEGQUALITY:
        sp->jpegquality = va_arg(ap, int);
        return (1);         /* pseudo tag */
    case TIFFTAG_JPEGCOLORMODE:
        sp->jpegcolormode = va_arg(ap, int);
                JPEGResetUpsampled( tif );
        return (1);         /* pseudo tag */
    case TIFFTAG_PHOTOMETRIC:
        {
                int ret_value = (*sp->vsetparent)(tif, tag, ap);
                JPEGResetUpsampled( tif );
                return ret_value;
        }
    case TIFFTAG_JPEGTABLESMODE:
        sp->jpegtablesmode = va_arg(ap, int);
        return (1);         /* pseudo tag */
    case TIFFTAG_YCBCRSUBSAMPLING:
                /* mark the fact that we have a real ycbcrsubsampling! */
        sp->ycbcrsampling_fetched = 1;
                /* should we be recomputing upsampling info here? */
        return (*sp->vsetparent)(tif, tag, ap);
    case TIFFTAG_FAXRECVPARAMS:
        sp->recvparams = va_arg(ap, uint32);
        break;
    case TIFFTAG_FAXSUBADDRESS:
        _TIFFsetString(&sp->subaddress, va_arg(ap, char*));
        break;
    case TIFFTAG_FAXRECVTIME:
        sp->recvtime = va_arg(ap, uint32);
        break;
    case TIFFTAG_FAXDCS:
        _TIFFsetString(&sp->faxdcs, va_arg(ap, char*));
        break;
    default:
        return (*sp->vsetparent)(tif, tag, ap);
    }

    if ((fip = _TIFFFieldWithTag(tif, tag))) {
        TIFFSetFieldBit(tif, fip->field_bit);
    } else {
        return (0);
    }

    tif->tif_flags |= TIFF_DIRTYDIRECT;
    return (1);
}

/*
 * Some JPEG-in-TIFF produces do not emit the YCBCRSUBSAMPLING values in
 * the TIFF tags, but still use non-default (2,2) values within the jpeg
 * data stream itself.  In order for TIFF applications to work properly
 * - for instance to get the strip buffer size right - it is imperative
 * that the subsampling be available before we start reading the image
 * data normally.  This function will attempt to load the first strip in
 * order to get the sampling values from the jpeg data stream.  Various
 * hacks are various places are done to ensure this function gets called
 * before the td_ycbcrsubsampling values are used from the directory structure,
 * including calling TIFFGetField() for the YCBCRSUBSAMPLING field from 
 * TIFFStripSize(), and the printing code in tif_print.c. 
 *
 * Note that JPEGPreDeocode() will produce a fairly loud warning when the
 * discovered sampling does not match the default sampling (2,2) or whatever
 * was actually in the tiff tags. 
 *
 * Problems:
 *  o This code will cause one whole strip/tile of compressed data to be
 *    loaded just to get the tags right, even if the imagery is never read.
 *    It would be more efficient to just load a bit of the header, and
 *    initialize things from that. 
 *
 * See the bug in bugzilla for details:
 *
 * http://bugzilla.remotesensing.org/show_bug.cgi?id=168
 *
 * Frank Warmerdam, July 2002
 */

static void 
JPEGFixupTestSubsampling( TIFF * tif )
{
#ifdef CHECK_JPEG_YCBCR_SUBSAMPLING
    JPEGState *sp = JState(tif);
    TIFFDirectory *td = &tif->tif_dir;

    JPEGInitializeLibJPEG( tif, 0, 0 );

    /*
     * Some JPEG-in-TIFF files don't provide the ycbcrsampling tags, 
     * and use a sampling schema other than the default 2,2.  To handle
     * this we actually have to scan the header of a strip or tile of
     * jpeg data to get the sampling.  
     */
    if( !sp->cinfo.comm.is_decompressor 
        || sp->ycbcrsampling_fetched  
        || td->td_photometric != PHOTOMETRIC_YCBCR )
        return;

    sp->ycbcrsampling_fetched = 1;
    if( TIFFIsTiled( tif ) )
    {
        if( !TIFFFillTile( tif, 0 ) )
            return;
    }
    else
    {
        if( !TIFFFillStrip( tif, 0 ) )
            return;
    }

    TIFFSetField( tif, TIFFTAG_YCBCRSUBSAMPLING, 
                  (uint16) sp->h_sampling, (uint16) sp->v_sampling );

    /*
    ** We want to clear the loaded strip so the application has time
    ** to set JPEGCOLORMODE or other behavior modifiers.  This essentially
    ** undoes the JPEGPreDecode triggers by TIFFFileStrip().  (#1936)
    */
    tif->tif_curstrip = -1;

#endif /* CHECK_JPEG_YCBCR_SUBSAMPLING */
}

static int
JPEGVGetField(TIFF* tif, ttag_t tag, va_list ap)
{
    JPEGState* sp = JState(tif);

    assert(sp != NULL);

    switch (tag) {
        case TIFFTAG_JPEGTABLES:
            *va_arg(ap, uint32*) = sp->jpegtables_length;
            *va_arg(ap, void**) = sp->jpegtables;
            break;
        case TIFFTAG_JPEGQUALITY:
            *va_arg(ap, int*) = sp->jpegquality;
            break;
        case TIFFTAG_JPEGCOLORMODE:
            *va_arg(ap, int*) = sp->jpegcolormode;
            break;
        case TIFFTAG_JPEGTABLESMODE:
            *va_arg(ap, int*) = sp->jpegtablesmode;
            break;
        case TIFFTAG_YCBCRSUBSAMPLING:
            JPEGFixupTestSubsampling( tif );
            return (*sp->vgetparent)(tif, tag, ap);
        case TIFFTAG_FAXRECVPARAMS:
            *va_arg(ap, uint32*) = sp->recvparams;
            break;
        case TIFFTAG_FAXSUBADDRESS:
            *va_arg(ap, char**) = sp->subaddress;
            break;
        case TIFFTAG_FAXRECVTIME:
            *va_arg(ap, uint32*) = sp->recvtime;
            break;
        case TIFFTAG_FAXDCS:
            *va_arg(ap, char**) = sp->faxdcs;
            break;
        default:
            return (*sp->vgetparent)(tif, tag, ap);
    }
    return (1);
}

static void
JPEGPrintDir(TIFF* tif, FILE* fd, long flags)
{
    JPEGState* sp = JState(tif);

    assert(sp != NULL);

    (void) flags;
    if (TIFFFieldSet(tif,FIELD_JPEGTABLES))
        fprintf(fd, "  JPEG Tables: (%lu bytes)\n",
            (unsigned long) sp->jpegtables_length);
        if (TIFFFieldSet(tif,FIELD_RECVPARAMS))
                fprintf(fd, "  Fax Receive Parameters: %08lx\n",
                   (unsigned long) sp->recvparams);
        if (TIFFFieldSet(tif,FIELD_SUBADDRESS))
                fprintf(fd, "  Fax SubAddress: %s\n", sp->subaddress);
        if (TIFFFieldSet(tif,FIELD_RECVTIME))
                fprintf(fd, "  Fax Receive Time: %lu secs\n",
                    (unsigned long) sp->recvtime);
        if (TIFFFieldSet(tif,FIELD_FAXDCS))
                fprintf(fd, "  Fax DCS: %s\n", sp->faxdcs);
}

static uint32
JPEGDefaultStripSize(TIFF* tif, uint32 s)
{
    JPEGState* sp = JState(tif);
    TIFFDirectory *td = &tif->tif_dir;

    s = (*sp->defsparent)(tif, s);
    if (s < td->td_imagelength)
        s = TIFFroundup(s, td->td_ycbcrsubsampling[1] * DCTSIZE);
    return (s);
}

static void
JPEGDefaultTileSize(TIFF* tif, uint32* tw, uint32* th)
{
    JPEGState* sp = JState(tif);
    TIFFDirectory *td = &tif->tif_dir;

    (*sp->deftparent)(tif, tw, th);
    *tw = TIFFroundup(*tw, td->td_ycbcrsubsampling[0] * DCTSIZE);
    *th = TIFFroundup(*th, td->td_ycbcrsubsampling[1] * DCTSIZE);
}

/*
 * The JPEG library initialized used to be done in TIFFInitJPEG(), but
 * now that we allow a TIFF file to be opened in update mode it is necessary
 * to have some way of deciding whether compression or decompression is
 * desired other than looking at tif->tif_mode.  We accomplish this by 
 * examining {TILE/STRIP}BYTECOUNTS to see if there is a non-zero entry.
 * If so, we assume decompression is desired. 
 *
 * This is tricky, because TIFFInitJPEG() is called while the directory is
 * being read, and generally speaking the BYTECOUNTS tag won't have been read
 * at that point.  So we try to defer jpeg library initialization till we
 * do have that tag ... basically any access that might require the compressor
 * or decompressor that occurs after the reading of the directory. 
 *
 * In an ideal world compressors or decompressors would be setup
 * at the point where a single tile or strip was accessed (for read or write)
 * so that stuff like update of missing tiles, or replacement of tiles could
 * be done. However, we aren't trying to crack that nut just yet ...
 *
 * NFW, Feb 3rd, 2003.
 */

static int JPEGInitializeLibJPEG( TIFF * tif, int force_encode, int force_decode )
{
    JPEGState* sp = JState(tif);
    uint32 *byte_counts = NULL;
    int     data_is_empty = TRUE;
    int     decompress;


    if(sp->cinfo_initialized)
    {
        if( force_encode && sp->cinfo.comm.is_decompressor )
            TIFFjpeg_destroy( sp );
        else if( force_decode && !sp->cinfo.comm.is_decompressor )
            TIFFjpeg_destroy( sp );
        else
            return 1;

        sp->cinfo_initialized = 0;
    }

    /*
     * Do we have tile data already?  Make sure we initialize the
     * the state in decompressor mode if we have tile data, even if we
     * are not in read-only file access mode. 
     */
    if( TIFFIsTiled( tif ) 
        && TIFFGetField( tif, TIFFTAG_TILEBYTECOUNTS, &byte_counts ) 
        && byte_counts != NULL )
    {
        data_is_empty = byte_counts[0] == 0;
    }
    if( !TIFFIsTiled( tif ) 
        && TIFFGetField( tif, TIFFTAG_STRIPBYTECOUNTS, &byte_counts) 
        && byte_counts != NULL )
    {
        data_is_empty = byte_counts[0] == 0;
    }

    if( force_decode )
        decompress = 1;
    else if( force_encode )
        decompress = 0;
    else if( tif->tif_mode == O_RDONLY )
        decompress = 1;
    else if( data_is_empty )
        decompress = 0;
    else
        decompress = 1;

    /*
     * Initialize libjpeg.
     */
    if ( decompress ) {
        if (!TIFFjpeg_create_decompress(sp))
            return (0);

    } else {
        if (!TIFFjpeg_create_compress(sp))
            return (0);
    }

    sp->cinfo_initialized = TRUE;

    return 1;
}

int
TIFFInitJPEG(TIFF* tif, int scheme)
{
    JPEGState* sp;

    assert(scheme == COMPRESSION_JPEG);

    /*
     * Merge codec-specific tag information.
     */
    if (!_TIFFMergeFieldInfo(tif, jpegFieldInfo, N(jpegFieldInfo))) {
        TIFFErrorExt(tif->tif_clientdata,
                 "TIFFInitJPEG",
                 "Merging JPEG codec-specific tags failed");
        return 0;
    }

    /*
     * Allocate state block so tag methods have storage to record values.
     */
    tif->tif_data = (tidata_t) _TIFFmalloc(sizeof (JPEGState));

    if (tif->tif_data == NULL) {
        TIFFErrorExt(tif->tif_clientdata,
                 "TIFFInitJPEG", "No space for JPEG state block");
        return 0;
    }
        _TIFFmemset(tif->tif_data, 0, sizeof(JPEGState));

    sp = JState(tif);
    sp->tif = tif;              /* back link */

    /*
     * Override parent get/set field methods.
     */
    sp->vgetparent = tif->tif_tagmethods.vgetfield;
    tif->tif_tagmethods.vgetfield = JPEGVGetField; /* hook for codec tags */
    sp->vsetparent = tif->tif_tagmethods.vsetfield;
    tif->tif_tagmethods.vsetfield = JPEGVSetField; /* hook for codec tags */
    sp->printdir = tif->tif_tagmethods.printdir;
    tif->tif_tagmethods.printdir = JPEGPrintDir;   /* hook for codec tags */

    /* Default values for codec-specific fields */
    sp->jpegtables = NULL;
    sp->jpegtables_length = 0;
    sp->jpegquality = 75;           /* Default IJG quality */
    sp->jpegcolormode = JPEGCOLORMODE_RAW;
    sp->jpegtablesmode = JPEGTABLESMODE_QUANT | JPEGTABLESMODE_HUFF;

        sp->recvparams = 0;
        sp->subaddress = NULL;
        sp->faxdcs = NULL;

        sp->ycbcrsampling_fetched = 0;

    /*
     * Install codec methods.
     */
    tif->tif_setupdecode = JPEGSetupDecode;
    tif->tif_predecode = JPEGPreDecode;
    tif->tif_decoderow = JPEGDecode;
    tif->tif_decodestrip = JPEGDecode;
    tif->tif_decodetile = JPEGDecode;
    tif->tif_setupencode = JPEGSetupEncode;
    tif->tif_preencode = JPEGPreEncode;
    tif->tif_postencode = JPEGPostEncode;
    tif->tif_encoderow = JPEGEncode;
    tif->tif_encodestrip = JPEGEncode;
    tif->tif_encodetile = JPEGEncode;
    tif->tif_cleanup = JPEGCleanup;
    sp->defsparent = tif->tif_defstripsize;
    tif->tif_defstripsize = JPEGDefaultStripSize;
    sp->deftparent = tif->tif_deftilesize;
    tif->tif_deftilesize = JPEGDefaultTileSize;
    tif->tif_flags |= TIFF_NOBITREV;    /* no bit reversal, please */

        sp->cinfo_initialized = FALSE;

    /*
        ** Create a JPEGTables field if no directory has yet been created. 
        ** We do this just to ensure that sufficient space is reserved for
        ** the JPEGTables field.  It will be properly created the right
        ** size later. 
        */
        if( tif->tif_diroff == 0 )
        {
#define SIZE_OF_JPEGTABLES 2000
/*
The following line assumes incorrectly that all JPEG-in-TIFF files will have
a JPEGTABLES tag generated and causes null-filled JPEGTABLES tags to be written
when the JPEG data is placed with TIFFWriteRawStrip.  The field bit should be 
set, anyway, later when actual JPEGTABLES header is generated, so removing it 
here hopefully is harmless.
            TIFFSetFieldBit(tif, FIELD_JPEGTABLES);
*/
            sp->jpegtables_length = SIZE_OF_JPEGTABLES;
            sp->jpegtables = (void *) _TIFFmalloc(sp->jpegtables_length);
        _TIFFmemset(sp->jpegtables, 0, SIZE_OF_JPEGTABLES);
#undef SIZE_OF_JPEGTABLES
        }

        /*
         * Mark the TIFFTAG_YCBCRSAMPLES as present even if it is not
         * see: JPEGFixupTestSubsampling().
         */
        TIFFSetFieldBit( tif, FIELD_YCBCRSUBSAMPLING );

    return 1;
}
#endif /* JPEG_SUPPORT */

/* vim: set ts=8 sts=8 sw=8 noet: */

/*
 * Local Variables:
 * mode: c
 * c-basic-offset: 8
 * fill-column: 78
 * End:
 */