TIFFGetField(3T)

NAME
TIFFGetField, TIFFVGetField - get the value(s) of a tag in an open TIFF file

SYNOPSIS
#include <tiffio.h>
int TIFFGetField(TIFF* tif, int tag, ...)

#include <stdarg.h>
int TIFFVGetField(TIFF* tif, int tag, va_list ap)

int TIFFGetFieldDefaulted(TIFF* tif, int tag, ...)
int TIFFVGetFieldDefaulted(TIFF* tif, int tag, va_list ap)

DESCRIPTION
TIFFGetField() returns the value of a tag in the current directory associated with the open TIFF file tif. The file must have been previously opened with TIFFOpen(3T). The tag is identified by tag, one of the values defined in the include file tiff.h (see also the table below). The type and number of values returned is dependent on the tag being requested. The programming interface uses a variable argument list as prescribed by the stdarg(3) interface (or, on some machines, the varargs(3) interface.) A 1 is returned if the tag is defined in the current directory; otherwise a 0 is returned. The returned values should only be interpreted if TIFFGetField() returns 1.

TIFFVGetField() is functionally equivalent to TIFFGetField(); except that it takes a pointer to a variable argument list. TIFFVGetField is useful for layering interfaces on top of the functionality provided of TIFFGetField.

TIFFGetFieldDefaulted() and TIFFVGetFieldDefaulted() are identical to TIFFGetField and TIFFVGetField, except that if a tag is not defined in the current directory and has a default value, the default value is returned.

The tags understood by libtiff, the number of parameter values, and the types for the returned values are shown below. The data types are specified as in C and correspond to the types used to specify tag values to TIFFSetField(3T). Remember that TIFFGetField() returns parameter values, so all the listed data types are pointers to storage where values should be returned. Consult the TIFF specification for information on the meaning of each tag and their possible values.

Tag Name	Count	Types	Notes

TIFFTAG_ARTIST	1	char**
TIFFTAG_BADFAXLINES	1	u_long*
TIFFTAG_BITSPERSAMPLE	1	u_short*
TIFFTAG_CLEANFAXDATA	1	u_short*
TIFFTAG_COLORMAP	3	u_short**	1<<BitsPerSample arrays
TIFFTAG_COMPRESSION	1	u_short*
TIFFTAG_CONSECUTIVEBADFAXLINES	1	u_long*
TIFFTAG_DATATYPE	1	u_short*
TIFFTAG_DATETIME	1	char**
TIFFTAG_DOCUMENTNAME	1	char**
TIFFTAG_DOTRANGE	2	u_short*
TIFFTAG_FILLORDER	1	u_short*
TIFFTAG_GROUP3OPTIONS	1	u_long*
TIFFTAG_GROUP4OPTIONS	1	u_long*
TIFFTAG_HALFTONEHINTS	2	u_short*
TIFFTAG_HOSTCOMPUTER	1	char**
TIFFTAG_IMAGEDEPTH	1	u_long*
TIFFTAG_IMAGEDESCRIPTION	1	char**
TIFFTAG_IMAGELENGTH	1	u_long*
TIFFTAG_IMAGEWIDTH	1	u_long*
TIFFTAG_INKNAMES	1	char**
TIFFTAG_INKSET	1	u_short*
TIFFTAG_JPEGACTABLES	1	u_char***	SamplesPerPixel arrays
TIFFTAG_JPEGDCTABLES	1	u_char***	SamplesPerPixel arrays
TIFFTAG_JPEGPROC	1	u_short*
TIFFTAG_JPEGRESTARTINTERVAL	1	u_short*
TIFFTAG_JPEGQTABLES	1	u_char***	SamplesPerPixel 64-entry arrays
TIFFTAG_MAKE	1	char**
TIFFTAG_MATTEING	1	u_short*
TIFFTAG_MAXSAMPLEVALUE	1	u_short*
TIFFTAG_MINSAMPLEVALUE	1	u_short*
TIFFTAG_MODEL	1	char**
TIFFTAG_ORIENTATION	1	u_short*
TIFFTAG_PAGENAME	1	char**
TIFFTAG_PAGENUMBER	2	u_short*
TIFFTAG_PHOTOMETRIC	1	u_short*
TIFFTAG_PLANARCONFIG	1	u_short*
TIFFTAG_PREDICTOR	1	u_short*
TIFFTAG_PRIMARYCHROMATICITIES	1	float**	6-entry array
TIFFTAG_REFERENCEBLACKWHITE	1	float**	2*SamplesPerPixel array
TIFFTAG_RESOLUTIONUNIT	1	u_short*
TIFFTAG_ROWSPERSTRIP	1	u_long*
TIFFTAG_SAMPLEFORMAT	1	u_short*
TIFFTAG_SAMPLESPERPIXEL	1	u_short*
TIFFTAG_SOFTWARE	1	char**
TIFFTAG_STRIPBYTECOUNTS	1	u_long**
TIFFTAG_STRIPOFFSETS	1	u_long**
TIFFTAG_SUBFILETYPE	1	u_long*
TIFFTAG_TARGETPRINTER	1	char**
TIFFTAG_THRESHHOLDING	1	u_short*
TIFFTAG_TILEBYTECOUNTS	1	u_long**
TIFFTAG_TILEDEPTH	1	u_long*
TIFFTAG_TILELENGTH	1	u_long*
TIFFTAG_TILEOFFSETS	1	u_long**
TIFFTAG_TILEWIDTH	1	u_long*
TIFFTAG_TRANSFERFUNCTION	S†	u_short**	1<<BitsPerSample entry arrays
TIFFTAG_WHITEPOINT	1	float**	2-entry array
TIFFTAG_XPOSITION	1	float*
TIFFTAG_XRESOLUTION	1	float*
TIFFTAG_YCBCRCOEFFICIENTS	1	float**	3-entry array
TIFFTAG_YCBCRPOSITIONING	1	u_short*
TIFFTAG_YCBCRSUBSAMPLING	2	u_short*
TIFFTAG_YPOSITION	1	float*
TIFFTAG_YRESOLUTION	1	float*
(† S indicates SamplesPerPixels parameters.)

DIAGNOSTICS
All error messages are directed to the TIFFError(3T) routine.

Unknown field, tag 0x%x. An unknown tag was supplied.

SEE ALSO
intro(3T), TIFFOpen(3T), TIFFSetField(3T), TIFFSetDirectory(3T), TIFFReadDirectory(3T), TIFFWriteDirectory(3T)