TIFFReadDirectory(3TIFF) TIFFReadDirectory(3TIFF)

NAME

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

SYNOPSIS

#include <tiffio.h>

int TIFFReadDirectory(TIFF *tif)

DESCRIPTION

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

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

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

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

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 required "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 required "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 required "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 required "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.

SEE ALSO

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

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

libtiff October 15, 1995 TIFFReadDirectory(3TIFF)