$Id: TIFFGetField.3tiff,v 1.8 2017-06-30 17:40:02 erouault Exp $

 Copyright (c) 1988-1997 Sam Leffler
 Copyright (c) 1991-1997 Silicon Graphics, Inc.

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 OF THIS SOFTWARE.

 TIFFGetField 3TIFF "March 18, 2005" "libtiff"
 NAME
TIFFGetField, TIFFVGetField - get the value(s) of a tag in an open
 TIFF file

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

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

 "int TIFFVGetFieldDefaulted(TIFF *" tif ", ttag_t " tag ", va_list " ap ")" 
 DESCRIPTION
 TIFFGetField returns the value of a tag or pseudo-tag associated with the the current
directory of the opened
 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 with
 TIFFOpen (3TIFF). 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. 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 by
 TIFFGetField . 

 TIFFGetFieldDefaulted and
 TIFFVGetFieldDefaulted are identical to 
 TIFFGetField and
 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.


The tags understood by
 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
 TIFFSetField (3TIFF). 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 (or relevant industry 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 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*,uint64** 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


\(dg If
 SamplesPerPixel is one, then a single array is returned; otherwise three arrays are returned.

\(dd The contents of this field are quite complex. See 
 "The ICC Profile Format Specification" , Annex B.3 "Embedding ICC Profiles in TIFF Files" (available at
http://www.color.org) for an explanation.

 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
 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:





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);







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

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


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

 "SEE ALSO"
 TIFFOpen (3TIFF),  TIFFSetField (3TIFF),  TIFFSetDirectory (3TIFF),  TIFFReadDirectory (3TIFF),  TIFFWriteDirectory (3TIFF)  libtiff (3TIFF), 

Libtiff library home page:
 http://www.simplesystems.org/libtiff/