TIFFReadDirectory(3T)		     Image Format Library C++ Reference	Manual

NAME    [Toc]    [Back]

     TIFFReadDirectory - get the contents of the next directory	in an open
     TIFF file

SYNOPSIS    [Toc]    [Back]

     #include <tiffio.h>
     int TIFFReadDirectory(TIFF* tif)

DESCRIPTION    [Toc]    [Back]

     Read the next directory in	the specified file and make it the current
     directory.	 Applications only need	to call	TIFFReadDirectory to read
     multiple subfiles in a single TIFF	file- the first	directory in a file is
     automatically read	when TIFFOpen is called.

NOTES    [Toc]    [Back]

     If	the library is compiled	with STRIPCHOP_SUPPORT enabled,	then images
     that have a single	uncompressed strip or tile of data are automatically
     treated as	if they	were made up of	multiple strips	or tiles of
     approximately 8 kilobytes each.  This operation is	done only in-memory;
     it	does not alter the contents of the file.  However, the construction of
     the ``chopped strips'' is visible to the application through the number
     of	strips [tiles] returned	by TIFFNumberOfStrips [TIFFNumberOfTiles].

RETURN VALUES    [Toc]    [Back]

     If	the next directory was successfully read, 1 is returned.  Otherwise, 0
     is	returned if an error was encountered, or if there are no more
     directories to be read.

DIAGNOSTICS    [Toc]    [Back]

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

     Seek error	accessing TIFF directory.  An error occurred while positioning
     to	the location of	the directory.

     Wrong data	type %d	for field "%s".	 The tag entry in the directory	had an
     incorrect data type.  For example,	an ImageDescription tag	with a SHORT
     data type.

     TIFF directory is missing required	"%s" field.  The specified tag is
     required to be present by the TIFF	5.0 specification, but is missing.
     The directory is (usually)	unusable.

     %s: Rational with zero denominator.  A directory tag has a	RATIONAL value
     whose denominator is zero.

     Incorrect count %d	for field "%s" (%lu, expecting %lu); tag ignored.  The
     specified tag's count field is bad.  For example, a count other than 1
     for a SubFileType tag.






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TIFFReadDirectory(3T)		     Image Format Library C++ Reference	Manual



     Cannot handle different per-sample	values for field "%s".	The tag	has
     SamplesPerPixel values and	they are not all the same; e.g.
     BitsPerSample.  The library is unable to handle images of this sort.

     Count mismatch for	field "%s"; expecting %d, got %d.  The count field in
     a tag does	not agree with the number expected by the library.  This
     should never happen, so if	it does, the library refuses to	read the
     directory.

     Invalid TIFF directory; tags are not sorted in ascending order.  The
     directory tags are	not properly sorted as specified in the	TIFF 5.0
     specification.  This error	is not fatal.

     Ignoring unknown field with tag %d	(0x%x).	 An unknown tag	was
     encountered in the	directory; the library ignores all such	tags.

     TIFF directory is missing requred "ImageLength" field.  The image
     violates the specification	by not having a	necessary field.  There	is no
     way for the library to recover from this error.

     TIFF directory is missing requred "PlanarConfig" field.  The image
     violates the specification	by not having a	necessary field.  There	is no
     way for the library to recover from this error.

     TIFF directory is missing requred "StripOffsets" field.  The image	has
     multiple strips, but is missing the tag that specifies the	file offset to
     each strip	of data.  There	is no way for the library to recover from this
     error.

     TIFF directory is missing requred "TileOffsets" field.  The image has
     multiple tiles, but is missing the	tag that specifies the file offset to
     each tile of data.	 There is no way for the library to recover from this
     error.

     TIFF directory is missing required	"StripByteCounts" field.  The image
     has multiple strips, but is missing the tag that specifies	the size of
     each strip	of data.  There	is no way for the library to recover from this
     error.

     TIFF directory is missing required	"StripByteCounts" field, calculating
     from imagelength.	The image violates the specification by	not having a
     necessary field.  However,	when the image is comprised of only one	strip
     or	tile, the library will estimate	the missing value based	on the file
     size.

     Bogus "StripByteCounts" field, ignoring and calculating from imagelength.
     Certain vendors violate the specification by writing zero for the
     StripByteCounts tag when they want	to leave the value unspecified.	 If
     the image has a single strip, the library will estimate the missing value
     based on the file size.





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TIFFReadDirectory(3T)		     Image Format Library C++ Reference	Manual

SEE ALSO    [Toc]    [Back]

     libtiff(3T), TIFFOpen(3T),	TIFFWriteDirectory(3T),	TIFFSetDirectory(3T),
     TIFFSetSubDirectory(3T)


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