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1994.02.12 05:32 "Problem using tiled images", by Timothy J. Wood
1994.02.12 05:43 "Problem using tiled images, continued", by Timothy J. Wood
1994.02.12 22:05 "Problems with tiles images (solution)", by Timothy J. Wood

1994.02.12 05:32 "Problem using tiled images", by Timothy J. Wood

I just recently started using libtiff, so I may be doing something obviously wrong. However, I didn't find any useful info in the archives. I have a feeling that if I spent a week or so figuring out tiffcp.c that my answer would lay in there, but I'm sure that the problem is simpler than that.

I'm using the latest version from sgi.com (v3.3) on a NeXT running NEXTSTEP 3.2.

What I am attempting to do is create an rather large tiff for later running through Aldus PrePrint on a Mac. To optimize the creation of the image, I need to be able to write the tiff as tiles. I wrote a test program (appended to the end of this message) that generate a 256x256 image consiting of a single tile. Running tiffdump on the output gives:

foo.tiff:
Magic: 0x4d4d <big-endian> Version: 0x2a
Directory 0: offset 138198 (0x21bd6)
ImageWidth (256) SHORT (3) 1<256>
ImageLength (257) SHORT (3) 1<256>
BitsPerSample (258) SHORT (3) 3<8 8 8>
Compression (259) SHORT (3) 1<5>
Photometric (262) SHORT (3) 1<2>
Orientation (274) SHORT (3) 1<1>
SamplesPerPixel (277) SHORT (3) 1<3>
RowsPerStrip (278) SHORT (3) 1<256>
MinSampleValue (280) SHORT (3) 3<0 0 0>
MaxSampleValue (281) SHORT (3) 3<255 255 255>
XResolution (282) RATIONAL (5) 1<300>
YResolution (283) RATIONAL (5) 1<300>
PlanarConfig (284) SHORT (3) 1<1>
ResolutionUnit (296) SHORT (3) 1<2>
TileWidth (322) SHORT (3) 1<256>
TileLength (323) SHORT (3) 1<256>
TileOffsets (324) LONG (4) 1<8>
TileByteCounts (325) LONG (4) 1<138190>

This seems fine to me, but when I run tiffdump on one of the sample images from sgi.com (cramps-tile.tiff), I get:

/Users/bungi/Source/Unix/libtiff/pics/cramps-tile.tiff:
Magic: 0x4d4d <big-endian> Version: 0x2a
Directory 0: offset 786440 (0xc0008)
ImageWidth (256) SHORT (3) 1<800>
ImageLength (257) SHORT (3) 1<607>
BitsPerSample (258) SHORT (3) 1<8>
Compression (259) SHORT (3) 1<1>
Photometric (262) SHORT (3) 1<0>
StripOffsets (273) LONG (4) 12<8 65544 131080 196616 262152 327688 393224
458760 524296 589832 655368 720904>
Orientation (274) SHORT (3) 1<1>
SamplesPerPixel (277) SHORT (3) 1<1>
RowsPerStrip (278) LONG (4) 1<256>
StripByteCounts (279) LONG (4) 12<65536 65536 65536 65536 65536 65536 65536
65536 65536 65536 65536 65536>
MinSampleValue (280) SHORT (3) 1<0>
MaxSampleValue (281) SHORT (3) 1<255>
PlanarConfig (284) SHORT (3) 1<1>
TileWidth (322) SHORT (3) 1<256>
TileLength (323) SHORT (3) 1<256>
OBSOLETE DataType (Silicon Graphics) (32996) SHORT (3) 1<0>
ImageDepth (Silicon Graphics) (32997) SHORT (3) 1<1>
TileDepth (Silicon Graphics) (32998) SHORT (3) 1<1>

Ignoring the SGI entries, the part that worries me is that the sample image is specified as being tiled, and yet it has tags for StripOffsets and StripByteCounts. My image, on the other hand, has TileOffsets and TileByteCounts. This seems more correct to me, but apparently its not since my image viewer loads the sample image correctly and not my image.

Any clues to these problems would be appreciated a lot.

Tim Wood
The Omni Group

--- tifftest.c ---

#include "tiffio.h"

#define TILE_SIZE 256

typedef struct {
        unsigned char r, g, b;
} pixel_t;
pixel_t image[TILE_SIZE][TILE_SIZE];

int main(int argc, char *argv[])
{
    TIFF               *tif;
    ttile_t             tile;
    int                 i, j;

    for (i = 0; i < TILE_SIZE; i++) {
        for (j = 0; j < TILE_SIZE; j++) {
            image[i][j].r = i;
            image[i][j].g = 0 /*(i < j) ? i : j*/;
            image[i][j].b = j;
        }
    }

    tif = TIFFOpen("foo.tiff", "w");

    /*
     * Don't know why this is necessary, but tiffdump reports no directories
     * if this isn't called 

     */
    TIFFSetDirectory(tif, 0);
    TIFFSetField(tif, TIFFTAG_IMAGEWIDTH, TILE_SIZE);
    TIFFSetField(tif, TIFFTAG_IMAGELENGTH, TILE_SIZE);
    TIFFSetField(tif, TIFFTAG_TILEWIDTH, TILE_SIZE);
    TIFFSetField(tif, TIFFTAG_TILELENGTH, TILE_SIZE);
    TIFFSetField(tif, TIFFTAG_BITSPERSAMPLE, 8);
    TIFFSetField(tif, TIFFTAG_COMPRESSION, COMPRESSION_LZW);
    TIFFSetField(tif, TIFFTAG_PHOTOMETRIC, PHOTOMETRIC_RGB);
    TIFFSetField(tif, TIFFTAG_ORIENTATION, ORIENTATION_TOPLEFT);
    TIFFSetField(tif, TIFFTAG_SAMPLESPERPIXEL, 3);
    TIFFSetField(tif, TIFFTAG_RESOLUTIONUNIT, RESUNIT_INCH);
    TIFFSetField(tif, TIFFTAG_XRESOLUTION, 300.0);
    TIFFSetField(tif, TIFFTAG_YRESOLUTION, 300.0);
    TIFFSetField(tif, TIFFTAG_PLANARCONFIG, PLANARCONFIG_CONTIG);
    TIFFSetField(tif, TIFFTAG_MINSAMPLEVALUE, 0);
    TIFFSetField(tif, TIFFTAG_MAXSAMPLEVALUE, 255);
    TIFFSetField(tif, TIFFTAG_ROWSPERSTRIP, TILE_SIZE);

    tile = TIFFComputeTile(tif, 0, 0, 0, 0);
    TIFFWriteEncodedTile(tif, tile, &image, TIFFTileSize(tif));

    TIFFClose(tif);

    exit(0);
}