TIFFReadDirectory(3TIFF)               TIFFReadDirectory(3TIFF)





NAME
       TIFFReadDirectory  - get the contents of the next direc-
       tory 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 automati-
       cally 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 approx-
       imately 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   [TIFFNum-
       berOfTiles].

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 (usu-
       ally) 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 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.  How-
       ever, 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 specifi-
       cation 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  miss-
       ing value based on the file size.

SEE ALSO
       TIFFOpen(3TIFF),  TIFFWriteDirectory(3TIFF),  TIFFSetDi-
       rectory(3TIFF),              TIFFSetSubDirectory(3TIFF),
       libtiff(3TIFF)

       Libtiff   library   home   page:  http://www.remotesens-
       ing.org/libtiff/



libtiff                 October 15, 199TIFFReadDirectory(3TIFF)
