tif_overview.c

TIFF文件格式读取及生成的源代码

/******************************************************************************
 * tif_overview.c,v 1.9 2005/05/25 09:03:16 dron Exp
 *
 * Project:  TIFF Overview Builder
 * Purpose:  Library function for building overviews in a TIFF file.
 * Author:   Frank Warmerdam, [e-mail]
 *
 * Notes:
 *  o Currently only images with bits_per_sample of a multiple of eight
 *    will work.
 *
 *  o The downsampler currently just takes the top left pixel from the
 *    source rectangle.  Eventually sampling options of averaging, mode, and
 *    ``center pixel'' should be offered.
 *
 *  o The code will attempt to use the same kind of compression,
 *    photometric interpretation, and organization as the source image, but
 *    it doesn't copy geotiff tags to the reduced resolution images.
 *
 *  o Reduced resolution overviews for multi-sample files will currently
 *    always be generated as PLANARCONFIG_SEPARATE.  This could be fixed
 *    reasonable easily if needed to improve compatibility with other
 *    packages.  Many don't properly support PLANARCONFIG_SEPARATE. 
 * 
 ******************************************************************************
 * Copyright (c) 1999, Frank Warmerdam
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included
 * in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 * DEALINGS IN THE SOFTWARE.
 ******************************************************************************
 */

#include <stdio.h>
#include <assert.h>
#include <stdlib.h>
#include <string.h>

#include "tiffio.h"
#include "tif_ovrcache.h"

#ifndef FALSE
#  define FALSE 0
#  define TRUE 1
#endif

#ifndef MAX
#  define MIN(a,b)      ((a<b) ? a : b)
#  define MAX(a,b)      ((a>b) ? a : b)
#endif

void TIFFBuildOverviews( TIFF *, int, int *, int, const char *,
                         int (*)(double,void*), void * );

/************************************************************************/
/*                         TIFF_WriteOverview()                         */
/*                                                                      */
/*      Create a new directory, without any image data for an overview. */
/*      Returns offset of newly created overview directory, but the     */
/*      current directory is reset to be the one in used when this      */
/*      function is called.                                             */
/************************************************************************/

uint32 TIFF_WriteOverview( TIFF *hTIFF, int nXSize, int nYSize,
                           int nBitsPerPixel, int nPlanarConfig, int nSamples, 
                           int nBlockXSize, int nBlockYSize,
                           int bTiled, int nCompressFlag, int nPhotometric,
                           int nSampleFormat,
                           unsigned short *panRed,
                           unsigned short *panGreen,
                           unsigned short *panBlue,
                           int bUseSubIFDs )

{
    uint32	nBaseDirOffset;
    uint32	nOffset;

    nBaseDirOffset = TIFFCurrentDirOffset( hTIFF );

    TIFFCreateDirectory( hTIFF );
    
/* -------------------------------------------------------------------- */
/*      Setup TIFF fields.                                              */
/* -------------------------------------------------------------------- */
    TIFFSetField( hTIFF, TIFFTAG_IMAGEWIDTH, nXSize );
    TIFFSetField( hTIFF, TIFFTAG_IMAGELENGTH, nYSize );
    if( nSamples == 1 )
        TIFFSetField( hTIFF, TIFFTAG_PLANARCONFIG, PLANARCONFIG_CONTIG );
    else
        TIFFSetField( hTIFF, TIFFTAG_PLANARCONFIG, nPlanarConfig );

    TIFFSetField( hTIFF, TIFFTAG_BITSPERSAMPLE, nBitsPerPixel );
    TIFFSetField( hTIFF, TIFFTAG_SAMPLESPERPIXEL, nSamples );
    TIFFSetField( hTIFF, TIFFTAG_COMPRESSION, nCompressFlag );
    TIFFSetField( hTIFF, TIFFTAG_PHOTOMETRIC, nPhotometric );
    TIFFSetField( hTIFF, TIFFTAG_SAMPLEFORMAT, nSampleFormat );

    if( bTiled )
    {
        TIFFSetField( hTIFF, TIFFTAG_TILEWIDTH, nBlockXSize );
        TIFFSetField( hTIFF, TIFFTAG_TILELENGTH, nBlockYSize );
    }
    else
        TIFFSetField( hTIFF, TIFFTAG_ROWSPERSTRIP, nBlockYSize );

    TIFFSetField( hTIFF, TIFFTAG_SUBFILETYPE, FILETYPE_REDUCEDIMAGE );
    
/* -------------------------------------------------------------------- */
/*	Write color table if one is present.				*/
/* -------------------------------------------------------------------- */
    if( panRed != NULL )
    {
        TIFFSetField( hTIFF, TIFFTAG_COLORMAP, panRed, panGreen, panBlue );
    }

/* -------------------------------------------------------------------- */
/*      Write directory, and return byte offset.                        */
/* -------------------------------------------------------------------- */
    if( TIFFWriteCheck( hTIFF, bTiled, "TIFFBuildOverviews" ) == 0 )
        return 0;

    TIFFWriteDirectory( hTIFF );
    TIFFSetDirectory( hTIFF, (tdir_t) (TIFFNumberOfDirectories(hTIFF)-1) );

    nOffset = TIFFCurrentDirOffset( hTIFF );

    TIFFSetSubDirectory( hTIFF, nBaseDirOffset );

    return nOffset;
}

/************************************************************************/
/*                       TIFF_GetSourceSamples()                        */
/************************************************************************/

static void 
TIFF_GetSourceSamples( double * padfSamples, unsigned char *pabySrc, 
                       int nPixelBytes, int nSampleFormat, 
                       int nXSize, int nYSize, 
                       int nPixelOffset, int nLineOffset )
{
    int  iXOff, iYOff, iSample;

    iSample = 0;

    for( iYOff = 0; iYOff < nYSize; iYOff++ )
    {
        for( iXOff = 0; iXOff < nXSize; iXOff++ )
        {
            unsigned char *pabyData;

            pabyData = pabySrc + iYOff * nLineOffset + iXOff * nPixelOffset;

            if( nSampleFormat == SAMPLEFORMAT_UINT && nPixelBytes == 1 )
            {
                padfSamples[iSample++] = *pabyData;
            }
            else if( nSampleFormat == SAMPLEFORMAT_UINT && nPixelBytes == 2 )
            {
                padfSamples[iSample++] = ((uint16 *) pabyData)[0];
            }
            else if( nSampleFormat == SAMPLEFORMAT_UINT && nPixelBytes == 4 )
            {
                padfSamples[iSample++] = ((uint32 *) pabyData)[0];
            }
            else if( nSampleFormat == SAMPLEFORMAT_INT && nPixelBytes == 2 )
            {
                padfSamples[iSample++] = ((int16 *) pabyData)[0];
            }
            else if( nSampleFormat == SAMPLEFORMAT_INT && nPixelBytes == 32 )
            {
                padfSamples[iSample++] = ((int32 *) pabyData)[0];
            }
            else if( nSampleFormat == SAMPLEFORMAT_IEEEFP && nPixelBytes == 4 )
            {
                padfSamples[iSample++] = ((float *) pabyData)[0];
            }
            else if( nSampleFormat == SAMPLEFORMAT_IEEEFP && nPixelBytes == 8 )
            {
                padfSamples[iSample++] = ((double *) pabyData)[0];
            }
        }
    }
} 

/************************************************************************/
/*                           TIFF_SetSample()                           */
/************************************************************************/

static void 
TIFF_SetSample( unsigned char * pabyData, int nPixelBytes, int nSampleFormat, 
                double dfValue )

{
    if( nSampleFormat == SAMPLEFORMAT_UINT && nPixelBytes == 1 )
    {
        *pabyData = (unsigned char) MAX(0,MIN(255,dfValue));
    }
    else if( nSampleFormat == SAMPLEFORMAT_UINT && nPixelBytes == 2 )
    {
        *((uint16 *)pabyData) = (uint16) MAX(0,MIN(65535,dfValue));
    }
    else if( nSampleFormat == SAMPLEFORMAT_UINT && nPixelBytes == 4 )
    {
        *((uint32 *)pabyData) = (uint32) dfValue;
    }
    else if( nSampleFormat == SAMPLEFORMAT_INT && nPixelBytes == 2 )
    {
        *((int16 *)pabyData) = (int16) MAX(-32768,MIN(32767,dfValue));
    }
    else if( nSampleFormat == SAMPLEFORMAT_INT && nPixelBytes == 32 )
    {
        *((int32 *)pabyData) = (int32) dfValue;
    }
    else if( nSampleFormat == SAMPLEFORMAT_IEEEFP && nPixelBytes == 4 )
    {
        *((float *)pabyData) = (float) dfValue;
    }
    else if( nSampleFormat == SAMPLEFORMAT_IEEEFP && nPixelBytes == 8 )
    {
        *((double *)pabyData) = dfValue;
    }
}

/************************************************************************/
/*                          TIFF_DownSample()                           */
/*                                                                      */
/*      Down sample a tile of full res data into a window of a tile     */
/*      of downsampled data.                                            */
/************************************************************************/

static
void TIFF_DownSample( unsigned char *pabySrcTile,
                      int nBlockXSize, int nBlockYSize,
                      int nPixelSkewBits, int nBitsPerPixel,
                      unsigned char * pabyOTile,
                      int nOBlockXSize, int nOBlockYSize,
                      int nTXOff, int nTYOff, int nOMult,
                      int nSampleFormat, const char * pszResampling )

{
    int		i, j, k, nPixelBytes = (nBitsPerPixel) / 8;
    int		nPixelGroupBytes = (nBitsPerPixel+nPixelSkewBits)/8;
    unsigned char *pabySrc, *pabyDst;
    double      *padfSamples;

    assert( nBitsPerPixel >= 8 );

    padfSamples = (double *) malloc(sizeof(double) * nOMult * nOMult);

/* ==================================================================== */
/*      Loop over scanline chunks to process, establishing where the    */
/*      data is going.                                                  */
/* ==================================================================== */
    for( j = 0; j*nOMult < nBlockYSize; j++ )
    {
        if( j + nTYOff >= nOBlockYSize )
            break;
            
        pabyDst = pabyOTile + ((j+nTYOff)*nOBlockXSize + nTXOff)
            * nPixelBytes * nPixelGroupBytes;

/* -------------------------------------------------------------------- */
/*      Handler nearest resampling ... we don't even care about the     */
/*      data type, we just do a bytewise copy.                          */
/* -------------------------------------------------------------------- */
        if( strncmp(pszResampling,"nearest",4) == 0
            || strncmp(pszResampling,"NEAR",4) == 0 )
        {
            pabySrc = pabySrcTile + j*nOMult*nBlockXSize * nPixelGroupBytes;

            for( i = 0; i*nOMult < nBlockXSize; i++ )
            {
                if( i + nTXOff >= nOBlockXSize )
                    break;
            
                /*
                 * For now use simple subsampling, from the top left corner
                 * of the source block of pixels.
                 */

                for( k = 0; k < nPixelBytes; k++ )
                    pabyDst[k] = pabySrc[k];

                pabyDst += nPixelBytes * nPixelGroupBytes;
                pabySrc += nOMult * nPixelGroupBytes;
            }
        }

/* -------------------------------------------------------------------- */
/*      Handle the case of averaging.  For this we also have to         */
/*      handle each sample format we are concerned with.                */
/* -------------------------------------------------------------------- */
        else if( strncmp(pszResampling,"averag",6) == 0 
                 || strncmp(pszResampling,"AVERAG",6) == 0 )
        {
            pabySrc = pabySrcTile + j*nOMult*nBlockXSize * nPixelGroupBytes;

            for( i = 0; i*nOMult < nBlockXSize; i++ )
            {
                double   dfTotal;
                int      iSample;
                int      nXSize, nYSize;

                if( i + nTXOff >= nOBlockXSize )
                    break;