TIFFReadDirectory

TIFFReadDirectory(3T)					TIFFReadDirectory(3T)



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  automati-
       cally  treated  as if they were made up of multiple strips or tiles of
       approximately 8 kilobytes each.	This operation is done	only  in-mem-
       ory;  it	 does  not alter the contents of the file.  However, the con-
       struction 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.   Other-
       wise,  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(3T)  routine.	  All
       warning messages are directed to the TIFFWarning(3T) routine.

       Seek  error  accessing  TIFF directory.	An error occurred while posi-
       tioning 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.   BitsPer-
       Sample.	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 encoun-
       tered in the directory; the library ignores all such tags.

       TIFF directory is missing requred "ImageLength" field.  The image vio-
       lates 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,  calculat-
       ing  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  image-
       length.	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(3T),   TIFFOpen(3T),   TIFFWriteDirectory(3T),	TIFFSetDirec-
       tory(3T), TIFFSetSubDirectory(3T)



			       October 15, 1995		TIFFReadDirectory(3T)