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.\" $Id: TIFFGetField.3tiff,v 1.6 2012-05-19 23:15:22 bfriesen Exp $

.\"

.\" Copyright (c) 1988-1997 Sam Leffler

.\" Copyright (c) 1991-1997 Silicon Graphics, Inc.

.\"

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.\" IN NO EVENT SHALL SAM LEFFLER OR SILICON GRAPHICS BE LIABLE FOR

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.\"

.if n .po 0

.TH TIFFGetField 3TIFF "March 18, 2005" "libtiff"

.SH NAME

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

.SM TIFF

file

.SH SYNOPSIS

.B "#include <tiffio.h>"

.sp

.BI "int TIFFGetField(TIFF *" tif ", ttag_t " tag ", " ... ")"

.sp

.B "#include <stdarg.h>"

.sp

.BI "int TIFFVGetField(TIFF *" tif ", ttag_t " tag ", va_list " ap ")"

.br

.BI "int TIFFGetFieldDefaulted(TIFF *" tif ", ttag_t " tag ", " ... ")"

.br

.BI "int TIFFVGetFieldDefaulted(TIFF *" tif ", ttag_t " tag ", va_list " ap ")"

.SH DESCRIPTION

.IR TIFFGetField

returns the value of a tag or pseudo-tag associated with the the current

directory of the opened

.SM TIFF

file

.IR tif .

(A

.I pseudo-tag 

is a parameter that is used to control the operation of the

.SM TIFF

library but whose value is not read or written to the underlying file.) The

file must have been previously opened with

.IR TIFFOpen (3TIFF).

The tag is identified by

.IR tag ,

one of the values defined in the include file

.B 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

.IR stdarg (3)

interface. The returned values should only be interpreted if

.IR TIFFGetField

returns 1.

.PP

.IR TIFFVGetField

is functionally equivalent to

.IR TIFFGetField

except that it takes a pointer to a variable argument list.

.I TIFFVGetField

is useful for layering interfaces on top of the functionality provided by

.IR TIFFGetField .

.PP

.IR TIFFGetFieldDefaulted

and

.IR TIFFVGetFieldDefaulted

are identical to 

.IR TIFFGetField

and

.IR TIFFVGetField ,

except that if a tag is not defined in the current directory and it has a

default value, then the default value is returned.

.PP

The tags understood by

.IR libtiff(3TIFF),

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

.IR TIFFSetField (3TIFF).

Remember that

.IR TIFFGetField

returns parameter values, so all the listed data types are pointers to storage

where values should be returned.

Consult the

.SM TIFF

specification (or relevant industry specification) for information on the

meaning of each tag and their possible values.

.PP

.nf

.ta \w'TIFFTAG_CONSECUTIVEBADFAXLINES'u+2n +\w'Count'u+2n +\w'TIFFFaxFillFunc*'u+2n

\fITag Name\fP	\fICount\fP	\fITypes\fP	\fINotes\fP

.sp 5p

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_COPYRIGHT	1	char**

TIFFTAG_DATATYPE	1	uint16*

TIFFTAG_DATETIME	1	char**

TIFFTAG_DOCUMENTNAME	1	char**

TIFFTAG_DOTRANGE	2	uint16*

TIFFTAG_EXTRASAMPLES	2	uint16*,uint16**	count & types array

TIFFTAG_FAXFILLFUNC	1	TIFFFaxFillFunc*	G3/G4 compression pseudo-tag

TIFFTAG_FAXMODE	1	int*	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_ICCPROFILE	2	uint32*,void**	count, profile data

TIFFTAG_IMAGEDEPTH	1	uint32*

TIFFTAG_IMAGEDESCRIPTION	1	char**

TIFFTAG_IMAGELENGTH	1	uint32*

TIFFTAG_IMAGEWIDTH	1	uint32*

TIFFTAG_INKNAMES	1	char**

TIFFTAG_INKSET	1	uint16*

TIFFTAG_JPEGCOLORMODE	1	int*	JPEG pseudo-tag

TIFFTAG_JPEGQUALITY	1	int*	JPEG pseudo-tag

TIFFTAG_JPEGTABLES	2	uint32*,void**	count & tables

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_PHOTOSHOP	2	uint32*,void**	count, data

TIFFTAG_PLANARCONFIG	1	uint16*

TIFFTAG_PREDICTOR	1	uint16*

TIFFTAG_PRIMARYCHROMATICITIES	1	float**	6-entry array

TIFFTAG_REFERENCEBLACKWHITE	1	float**	6-entry array

TIFFTAG_RESOLUTIONUNIT	1	uint16*

TIFFTAG_RICHTIFFIPTC	2	uint32*,void**	count, data

TIFFTAG_ROWSPERSTRIP	1	uint32*

TIFFTAG_SAMPLEFORMAT	1	uint16*

TIFFTAG_SAMPLESPERPIXEL	1	uint16*

TIFFTAG_SMAXSAMPLEVALUE	1	double*

TIFFTAG_SMINSAMPLEVALUE	1	double*

TIFFTAG_SOFTWARE	1	char**

TIFFTAG_STONITS	1	double**

TIFFTAG_STRIPBYTECOUNTS	1	uint32**

TIFFTAG_STRIPOFFSETS	1	uint32**

TIFFTAG_SUBFILETYPE	1	uint32*

TIFFTAG_SUBIFD	2	uint16*,uint32**	count & offsets array

TIFFTAG_TARGETPRINTER	1	char**

TIFFTAG_THRESHHOLDING	1	uint16*

TIFFTAG_TILEBYTECOUNTS	1	uint32**

TIFFTAG_TILEDEPTH	1	uint32*

TIFFTAG_TILELENGTH	1	uint32*

TIFFTAG_TILEOFFSETS	1	uint32**

TIFFTAG_TILEWIDTH	1	uint32*

TIFFTAG_TRANSFERFUNCTION	1 or 3\(dg	uint16**1<<BitsPerSample entry arrays

TIFFTAG_WHITEPOINT	1	float**	2-entry array

TIFFTAG_XMLPACKET	2	uint32*,void**	count, data

TIFFTAG_XPOSITION	1	float*

TIFFTAG_XRESOLUTION	1	float*

TIFFTAG_YCBCRCOEFFICIENTS	1	float**	3-entry array

TIFFTAG_YCBCRPOSITIONING	1	uint16*

TIFFTAG_YCBCRSUBSAMPLING	2	uint16*

TIFFTAG_YPOSITION	1	float*

TIFFTAG_YRESOLUTION	1	float*\(dd

.fi

\(dg If

.I SamplesPerPixel

is one, then a single array is returned; otherwise three arrays are returned.

.fi

\(dd The contents of this field are quite complex.  See 

.IR "The ICC Profile Format Specification" ,

Annex B.3 "Embedding ICC Profiles in TIFF Files" (available at

http://www.color.org) for an explanation.

.SH AUTOREGISTERED TAGS

If you can't find the tag in the table above that means this is an unsupported

tag and is not directly supported by

.BR libtiff(3TIFF)

library. You will still be able to read it's value if you know the data type of

that tag. For example, if you want to read the LONG value from the tag 33424

and ASCII string from the tag 36867 you can use the following code:

.PP

.RS

.nf

uint32  count;

void    *data;

TIFFGetField(tiff, 33424, &count, &data);

printf("Tag %d: %d, count %d\n", 33424, *(uint32 *)data, count);

TIFFGetField(tiff, 36867, &count, &data);

printf("Tag %d: %s, count %d\n", 36867, (char *)data, count);

.fi

.RE

.PP

.SH RETURN VALUES

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

returned.

.SH DIAGNOSTICS

All error messages are directed to the

.BR TIFFError (3TIFF)

routine.

.PP

.BR "Unknown field, tag 0x%x" .

An unknown tag was supplied.

.SH "SEE ALSO"

.BR TIFFOpen (3TIFF),

.BR TIFFSetField (3TIFF),

.BR TIFFSetDirectory (3TIFF),

.BR TIFFReadDirectory (3TIFF),

.BR TIFFWriteDirectory (3TIFF)

.BR libtiff (3TIFF),

.PP

Libtiff library home page:

.BR http://www.remotesensing.org/libtiff/