libtiff/html/man/TIFFGetField.3t.html
1999-11-23 04:29:23 +00:00

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<H1>TIFFGetField</H1>
Section: Misc. Reference Manual Pages (3T)<BR>Updated: August 22, 1997<BR><A HREF="#index">Index</A>
<BR><A HREF="index.html">Return to Main Contents</A>
<HR>
<A NAME="lbAB">&nbsp;</A>
<H2>NAME</H2>
TIFFGetField, TIFFVGetField - get the value(s) of a tag in an open
<FONT SIZE="-1">TIFF</FONT>
file
<A NAME="lbAC">&nbsp;</A>
<H2>SYNOPSIS</H2>
<B>#include &lt;<A HREF="file:/usr/include/tiffio.h">tiffio.h</A>&gt;</B>
<BR>
<B>int TIFFGetField(TIFF* tif, ttag_t tag, ...)</B>
<P>
<B>#include &lt;<A HREF="file:/usr/include/stdarg.h">stdarg.h</A>&gt;</B>
<BR>
<B>int TIFFVGetField(TIFF* tif, ttag_t tag, va_list ap)</B>
<P>
<B>int TIFFGetFieldDefaulted(TIFF* tif, ttag_t tag, ...)</B>
<BR>
<B>int TIFFVGetFieldDefaulted(TIFF* tif, ttag_t tag, va_list ap)</B>
<A NAME="lbAD">&nbsp;</A>
<H2>DESCRIPTION</H2>
<I>TIFFGetField</I>
returns the value of a tag or pseudo-tag associated with the
the current directory of the open
<FONT SIZE="-1">TIFF</FONT>
file
<I>tif</I>.
(A
<I>pseudo-tag </I>
is a parameter that is used to control the operation of the
<FONT SIZE="-1">TIFF</FONT>
library but whose value is not read or written to the underlying file.)
The file must have been previously opened with
<I><A HREF="TIFFOpen.3t.html">TIFFOpen</A></I>(3T).
The tag is identified by
<I>tag</I>,
one of the values defined in the include file
<B>tiff.h</B>
(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
<I><A HREF="stdarg+3">stdarg</A></I>(3)
interface.
The returned values should only be interpreted if
<I>TIFFGetField</I>
returns 1.
<P>
<I>TIFFVGetField</I>
is functionally equivalent to
<I>TIFFGetField</I>
except that it takes a pointer to a variable
argument list.
<I>TIFFVGetField</I>
is useful for layering interfaces on top of
the functionality provided by
<I>TIFFGetField</I>.
<P>
<I>TIFFGetFieldDefaulted</I>
and
<I>TIFFVGetFieldDefaulted</I>
are identical to
<I>TIFFGetField</I>
and
<I>TIFFVGetField</I>,
except that if a tag is not defined in the current directory
and it has a default value, then the default value is returned.
<P>
The tags understood by
<I>libtiff</I>,
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
<I><A HREF="TIFFSetField.3t.html">TIFFSetField</A></I>(3T).
Remember that
<I>TIFFGetField</I>
returns parameter values, so all the listed
data types are pointers to storage where values
should be returned.
Consult the
<FONT SIZE="-1">TIFF</FONT>
specification for information on the meaning of
each tag and their possible values.
<P>
<PRE>
<I>Tag Name</I> <I>Count</I> <I>Types</I> <I>Notes</I>
TIFFTAG_ARTIST 1 char**
TIFFTAG_BADFAXLINES 1 uint32*
TIFFTAG_BITSPERSAMPLE 1 uint16*
TIFFTAG_CLEANFAXDATA 1 uint16*
TIFFTAG_COLORMAP 3 uint16** 1&lt;&lt;BitsPerSample arrays
TIFFTAG_COMPRESSION 1 uint16*
TIFFTAG_CONSECUTIVEBADFAXLINES 1 uint32*
TIFFTAG_DATATYPE 1 uint16*
TIFFTAG_DATETIME 1 char**
TIFFTAG_DOCUMENTNAME 1 char**
TIFFTAG_DOTRANGE 2 uint16*
TIFFTAG_EXTRASAMPLES 2 uint16*,uint16** count &amp; 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_IMAGEDEPTH 1 uint32*
TIFFTAG_IMAGEDESCRIPTION 1 char**
TIFFTAG_IMAGELENGTH 1 uint32*
TIFFTAG_IMAGEWIDTH 1 uint32*
TIFFTAG_INKNAMES 1 char**
TIFFTAG_INKSET 1 uint16*
TIFFTAG_JPEGTABLES 2 u_short*,void** count &amp; 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*
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 &amp; 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&lt;&lt;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 uint16*
TIFFTAG_YCBCRSUBSAMPLING 2 uint16*
TIFFTAG_YPOSITION 1 float*
TIFFTAG_YRESOLUTION 1 float*
TIFFTAG_ICCPROFILE 2 uint32*,void** count, profile datadd
</PRE>
+ If
<I>SamplesPerPixel</I>
is one, then a single array is returned; otherwise three arrays are
returned.
dd The contents of this field are quite complex. See
<I>The ICC Profile Format Specification</I>,
Annex B.3 &quot;Embedding ICC Profiles in TIFF Files&quot;
(available at <A HREF="http://www.color.org)">http://www.color.org)</A> for an explanation.
<A NAME="lbAE">&nbsp;</A>
<H2>RETURN VALUES</H2>
1 is returned if the tag is defined in the current
directory; otherwise a 0 is returned.
<A NAME="lbAF">&nbsp;</A>
<H2>DIAGNOSTICS</H2>
All error messages are directed to the
<I><A HREF="TIFFError.3t.html">TIFFError</A></I>(3T)
routine.
<P>
<B>Unknown field, tag 0x%x</B>.
An unknown tag was supplied.
<A NAME="lbAG">&nbsp;</A>
<H2>SEE ALSO</H2>
<I><A HREF="libtiff.3t.html">libtiff</A></I>(3T),
<I><A HREF="TIFFOpen.3t.html">TIFFOpen</A></I>(3T),
<I><A HREF="TIFFSetField.3t.html">TIFFSetField</A></I>(3T),
<I><A HREF="TIFFSetDirectory.3t.html">TIFFSetDirectory</A></I>(3T),
<I><A HREF="TIFFReadDirectory.3t.html">TIFFReadDirectory</A></I>(3T),
<I><A HREF="TIFFWriteDirectory.3t.html">TIFFWriteDirectory</A></I>(3T)
<HR>
<A NAME="index">&nbsp;</A><H2>Index</H2>
<DL>
<DT><A HREF="#lbAB">NAME</A><DD>
<DT><A HREF="#lbAC">SYNOPSIS</A><DD>
<DT><A HREF="#lbAD">DESCRIPTION</A><DD>
<DT><A HREF="#lbAE">RETURN VALUES</A><DD>
<DT><A HREF="#lbAF">DIAGNOSTICS</A><DD>
<DT><A HREF="#lbAG">SEE ALSO</A><DD>
</DL>
<HR>
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Time: 01:31:37 GMT, November 23, 1999
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