TIFFSetField(3T)

NAME
TIFFSetField - set the value(s) of a tag in a TIFF file open for writing

SYNOPSIS
#include <tiffio.h>
int TIFFSetField(TIFF* tif, ttag_t tag, ...)
#include <stdarg.h>
int TIFFVSetField(TIFF* tif, ttag_t tag, va_list ap)

DESCRIPTION
TIFFSetField sets the value of a field or pseudo-tag in the current directory associated with the open TIFF file tif. (A pseudo-tag is a parameter that is used to control the operation of the TIFF library but whose value is not read or written to the underlying file.) The file must have been previously opened for writing with TIFFOpen(3T). The field is identified by tag, one of the values defined in the include file tiff.h (see also the table below). The actual value is specified using a variable argument list, as prescribed by the stdarg(3) interface (or, on some machines, the varargs(3) interface.)

TIFFVSetField is functionally equivalent to TIFFSetField except that it takes a pointer to a variable argument list. TIFFVSetField is useful for writing routines that are layered on top of the functionality provided by TIFFSetField.

The tags understood by libtiff, the number of parameter values, and the expected types for the parameter values are shown below. The data types are: char* is null-terminated string and corresponds to the ASCII data type; uint16 is an unsigned 16-bit value; uint32 is an unsigned 32-bit value; uint16* is an array of unsigned 16-bit values. Consult the TIFF specification for information on the meaning of each tag.

Tag Name	Count	Types	Notes

TIFFTAG_ARTIST	1	char*
TIFFTAG_BADFAXLINES	1	uint32
TIFFTAG_BITSPERSAMPLE	1	uint16	†
TIFFTAG_CLEANFAXDATA	1	uint16
TIFFTAG_COLORMAP	3	uint16*	1<<BitsPerSample arrays
TIFFTAG_COMPRESSION	1	uint16	†
TIFFTAG_CONSECUTIVEBADFAXLINES	1	uint32
TIFFTAG_DATETIME	1	char*
TIFFTAG_DOCUMENTNAME	1	char*
TIFFTAG_DOTRANGE	2	uint16
TIFFTAG_EXTRASAMPLES	2	uint16,uint16*	† count & types array
TIFFTAG_FAXMODE	1	int	† G3/G4 compression pseudo-tag
TIFFTAG_FAXFILLFUNC	1	TIFFFaxFillFunc	G3/G4 compression pseudo-tag
TIFFTAG_FILLORDER	1	uint16	†
TIFFTAG_GROUP3OPTIONS	1	uint32	†
TIFFTAG_GROUP4OPTIONS	1	uint32	†
TIFFTAG_HALFTONEHINTS	2	uint16
TIFFTAG_HOSTCOMPUTER	1	char*
TIFFTAG_IMAGEDESCRIPTION	1	char*
TIFFTAG_IMAGEDEPTH	1	uint32	†
TIFFTAG_IMAGELENGTH	1	uint32
TIFFTAG_IMAGEWIDTH	1	uint32	†
TIFFTAG_INKNAMES	1	char*
TIFFTAG_INKSET	1	uint16	†
TIFFTAG_JPEGTABLES	2	uint32*,void*	† count & tables
TIFFTAG_JPEGQUALITY	1	int	JPEG pseudo-tag
TIFFTAG_JPEGCOLORMODE	1	int	† JPEG pseudo-tag
TIFFTAG_JPEGTABLESMODE	1	int	† JPEG pseudo-tag
TIFFTAG_MAKE	1	char*
TIFFTAG_MATTEING	1	uint16	†
TIFFTAG_MAXSAMPLEVALUE	1	uint16
TIFFTAG_MINSAMPLEVALUE	1	uint16
TIFFTAG_MODEL	1	char*
TIFFTAG_ORIENTATION	1	uint16
TIFFTAG_PAGENAME	1	char*
TIFFTAG_PAGENUMBER	2	uint16
TIFFTAG_PHOTOMETRIC	1	uint16
TIFFTAG_PLANARCONFIG	1	uint16	†
TIFFTAG_PREDICTOR	1	uint16	†
TIFFTAG_PRIMARYCHROMATICITIES	1	float	6-entry array
TIFFTAG_REFERENCEBLACKWHITE	1	float*	† 2*SamplesPerPixel array
TIFFTAG_RESOLUTIONUNIT	1	uint16
TIFFTAG_ROWSPERSTRIP	1	uint32	† must be > 0
TIFFTAG_SAMPLEFORMAT	1	uint16	†
TIFFTAG_SAMPLESPERPIXEL	1	uint16	† value must be <= 4
TIFFTAG_SMAXSAMPLEVALUE	1	double
TIFFTAG_SMINSAMPLEVALUE	1	double
TIFFTAG_SOFTWARE	1	char*
TIFFTAG_SUBFILETYPE	1	uint32
TIFFTAG_SUBIFD	2	uint16,uint32*	count & offsets array
TIFFTAG_TARGETPRINTER	1	char*
TIFFTAG_THRESHHOLDING	1	uint16
TIFFTAG_TILEDEPTH	1	uint32	†
TIFFTAG_TILELENGTH	1	uint32	† must be a multiple of 8
TIFFTAG_TILEWIDTH	1	uint32	† must be a multiple of 8
TIFFTAG_TRANSFERFUNCTION	1 or 3 ‡	uint16*	1<<BitsPerSample entry arrays
TIFFTAG_XPOSITION	1	float
TIFFTAG_XRESOLUTION	1	float
TIFFTAG_WHITEPOINT	1	float	2-entry array
TIFFTAG_YCBCRCOEFFICIENTS	1	float*	† 3-entry array
TIFFTAG_YCBCRPOSITIONING	1	uint16	†
TIFFTAG_YCBCRSAMPLING	2	uint16	†
TIFFTAG_YPOSITION	1	float
TIFFTAG_YRESOLUTION	1	float

† Tag may not have its values changed once data is written.
‡ If SamplesPerPixel is one, then a single array is passed; otherwise three arrays should be passed.

RETURN VALUES
1 is returned if the tag is defined in the current directory; otherwise a 0 is returned.

RETURN VALUES
1 is returned if the operation was successful. Otherwise, 0 is returned if an error was detected.

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

%s: Cannot modify tag "%s" while writing. Data has already been written to the file, so the specified tag's value can not be changed. This restriction is applied to all tags that affect the format of written data.

%d: Bad value for "%s". An invalid value was supplied for the named tag.

SEE ALSO
libtiff(3T), TIFFOpen(3T), TIFFGetField(3T), TIFFSetDirectory(3T), TIFFWriteDirectory(3T), TIFFReadDirectory(3T)