TIFFReadDirectory(3tiff)

TIFFReadDirectory(3TIFFMISC. REFERENCE MANUAL PAGETIFFReadDirectory(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 TIF-
     FReadDirectory 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) rou-
     tine.    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  speci-
     fied  tag is required to be present by the TIFF 5.0 specifi-
     cation, but is missing.  The directory  is  (usually)  unus-
     able.

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

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     Incorrect count %d for field "%s" (%lu, expecting %lu);  tag
     ignored.  The specified tag's count field is bad.  For exam-
     ple, 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 speci-
     fied 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 speci-
     fies 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

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     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

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

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