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*,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† 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*‡
† If
SamplesPerPixel is one, then a single array is returned;
otherwise three arrays are returned.
‡ 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.
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 %d0, 33424, *(uint32 *)data, count);
TIFFGetField(tiff, 36867, &count, &data);
printf("Tag %d: %s, count %d0, 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.remotesensing.org/libtiff/