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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)

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