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2003.11.17 15:16 "TIFF, v3.6.0. Fetching "custom" tags", by Andrey Kiselev
On Sun, Nov 16, 2003 at 07:45:43PM -0500, Chris Losinger wrote:
> "Custom tags can be set and fetched normally using TIFFSetField() and
> TIFFGetField(), and appear pretty much like normal tags to application
> code. "
>
> I assume I can get rid of the tags/xtiff stuff and LibTiff will
> happily read and store any tags that it finds, even non-core tags, like
> 34665.
>
> But, it doesn't seem to be working. When reading the TIFF dir, i
> get warnings about "unknown field with tag 34665 (0x8769) encountered", and
> when i call TIFFGetField, nothing is returned. It looks like v3.6.0. is
> behaving pretty much exactly like 3.5.7: complain about strange tags, then
> ignore them. But that's not what the documentation says is supposed to
> happen.
You should register all extended tags before you can work with them. See
a sample code attached.
Andrey
--
Andrey V. Kiselev
Home phone: +7 812 5274898 ICQ# 26871517
#include <tiffio.h>
#include <stdio.h>
#define TIFFTAG_ASCIITAG 666
#define TIFFTAG_LONGTAG 667
#define TIFFTAG_SHORTTAG 668
#define TIFFTAG_RATIONALTAG 669
#define TIFFTAG_FLOATTAG 670
#define TIFFTAG_DOUBLETAG 671
#define TIFFTAG_BYTE 672
static void TagExtender(TIFF *tiff)
{
static const TIFFFieldInfo xtiffFieldInfo[] = {
{ TIFFTAG_ASCIITAG, -1,-1, TIFF_ASCII, FIELD_CUSTOM,
1, 0, "MyTag" },
{ TIFFTAG_SHORTTAG, 2, 2, TIFF_SHORT, FIELD_CUSTOM, 0, 1,
"ShortTag" },
{ TIFFTAG_LONGTAG, 2, 2, TIFF_LONG, FIELD_CUSTOM, 0, 1,
"LongTag" },
{ TIFFTAG_RATIONALTAG, 2, 2, TIFF_RATIONAL, FIELD_CUSTOM, 0, 1,
"RationalTag" },
{ TIFFTAG_FLOATTAG, 2, 2, TIFF_FLOAT, FIELD_CUSTOM, 0, 1,
"FloatTag" },
{ TIFFTAG_DOUBLETAG, 2, 2, TIFF_DOUBLE, FIELD_CUSTOM, 0, 1,
"DoubleTag" },
{ TIFFTAG_BYTE, 2, 2, TIFF_BYTE, FIELD_CUSTOM, 0, 1,
"DoubleTag" },
};
TIFFMergeFieldInfo( tiff, xtiffFieldInfo,
sizeof(xtiffFieldInfo) / sizeof(xtiffFieldInfo[0]) );
}
int main()
{
TIFF *tiff;
char *pszString;
long aiLong[2], *paiLong;
short aiShort[2], *paiShort;
float afFloat[2], *pafFloat;
double adfDouble[2], *padfDouble;
char aiByte[2], *paiByte;
unsigned short iCount;
char *buf;
/* Register the custom tag hadler */
TIFFSetTagExtender(TagExtender);
/* Create a new TIFF with the bunch of custom tags */
tiff = TIFFOpen("new.tif", "w");
TIFFSetField(tiff, TIFFTAG_IMAGEWIDTH, 256);
TIFFSetField(tiff, TIFFTAG_IMAGELENGTH, 256);
TIFFSetField(tiff, TIFFTAG_BITSPERSAMPLE, 8);
TIFFSetField(tiff, TIFFTAG_SAMPLESPERPIXEL, 3);
TIFFSetField(tiff, TIFFTAG_PLANARCONFIG, PLANARCONFIG_CONTIG);
TIFFSetField(tiff, TIFFTAG_ORIENTATION, ORIENTATION_TOPLEFT);
TIFFSetField(tiff, TIFFTAG_ASCIITAG, "Tag contents");
aiShort[0] = 263; aiShort[1] = 264;
TIFFSetField(tiff, TIFFTAG_SHORTTAG, 2, aiShort);
aiLong[0] = 117; aiLong[1] = 118;
TIFFSetField(tiff, TIFFTAG_LONGTAG, 2, aiLong);
afFloat[0] = 0.333333; afFloat[1] = 0.444444;
TIFFSetField(tiff, TIFFTAG_RATIONALTAG, 2, afFloat);
afFloat[0] = 0.666666; afFloat[1] = 0.777777;
TIFFSetField(tiff, TIFFTAG_FLOATTAG, 2, afFloat);
adfDouble[0] = 0.1234567; adfDouble[1] = 0.7654321;
TIFFSetField(tiff, TIFFTAG_DOUBLETAG, 2, adfDouble);
aiByte[0] = 89; aiByte[1] = 90;
TIFFSetField(tiff, TIFFTAG_BYTE, 2, aiByte);
buf = _TIFFmalloc(3 * 256 * 256);
TIFFWriteEncodedStrip(tiff, 0, buf, 3 * 256 * 256);
_TIFFfree(buf);
TIFFClose(tiff);
/* Now open that TIFF back and read new tags */
tiff = TIFFOpen("new.tif", "r");
TIFFGetField(tiff, TIFFTAG_ASCIITAG, &pszString);
printf("ASCII tag: %s\n", pszString);
TIFFGetField(tiff, TIFFTAG_SHORTTAG, &iCount, &paiShort);
if (iCount == 2)
printf("Short tag: %d\n", paiShort[0]);
TIFFGetField(tiff, TIFFTAG_LONGTAG, &iCount, &paiLong);
if (iCount == 2)
printf("Long tag: %ld\n", paiLong[0]);
TIFFGetField(tiff, TIFFTAG_RATIONALTAG, &iCount, &pafFloat);
if (iCount == 2)
printf("Rational tag: %f\n", pafFloat[0]);
TIFFGetField(tiff, TIFFTAG_FLOATTAG, &iCount, &pafFloat);
if (iCount == 2)
printf("Float tag: %f\n", pafFloat[0]);
TIFFGetField(tiff, TIFFTAG_DOUBLETAG, &iCount, &padfDouble);
if (iCount == 2)
printf("Double tag: %lf\n", padfDouble[0]);
TIFFGetField(tiff, TIFFTAG_BYTE, &iCount, &paiByte);
if (iCount == 2)
printf("Byte tag: %d\n", paiByte[0]);
TIFFClose(tiff);
return 0;
}