src/tiff/man/TIFFReadDirectory.3tiff

.\" $Id: TIFFReadDirectory.3tiff,v 1.2 2005/11/02 11:07:18 dron Exp $
.\"
.\" Copyright (c) 1988-1997 Sam Leffler
.\" Copyright (c) 1991-1997 Silicon Graphics, Inc.
.\"
.\" Permission to use, copy, modify, distribute, and sell this software and
.\" its documentation for any purpose is hereby granted without fee, provided
.\" that (i) the above copyright notices and this permission notice appear in
.\" all copies of the software and related documentation, and (ii) the names of
.\" Sam Leffler and Silicon Graphics may not be used in any advertising or
.\" publicity relating to the software without the specific, prior written
.\" permission of Sam Leffler and Silicon Graphics.
.\"
.\" THE SOFTWARE IS PROVIDED "AS-IS" AND WITHOUT WARRANTY OF ANY KIND,
.\" EXPRESS, IMPLIED OR OTHERWISE, INCLUDING WITHOUT LIMITATION, ANY
.\" WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
.\"
.\" IN NO EVENT SHALL SAM LEFFLER OR SILICON GRAPHICS BE LIABLE FOR
.\" ANY SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY KIND,
.\" OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
.\" WHETHER OR NOT ADVISED OF THE POSSIBILITY OF DAMAGE, AND ON ANY THEORY OF
.\" LIABILITY, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
.\" OF THIS SOFTWARE.
.\"
.if n .po 0
.TH TIFFReadDirectory 3TIFF "October 15, 1995" "libtiff"
.SH NAME
TIFFReadDirectory \- get the contents of the next directory in an open
.SM TIFF
file
.SH SYNOPSIS
.B "#include <tiffio.h>"
.sp
.BI "int TIFFReadDirectory(TIFF *" tif ")"
.SH DESCRIPTION
Read the next directory in the specified file and make it the current
directory. Applications only need to call
.I TIFFReadDirectory
to read multiple subfiles in a single
.SM TIFF
file\(em
the first directory in a file is automatically read when
.IR TIFFOpen
is called.
.SH NOTES
If the library is compiled with
.SM 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
.I TIFFNumberOfStrips
[\c
.IR TIFFNumberOfTiles ].
.SH "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.
.SH DIAGNOSTICS
All error messages are directed to the
.IR TIFFError (3TIFF)
routine.
All warning messages are directed to the
.IR TIFFWarning (3TIFF)
routine.
.PP
\fBSeek error accessing TIFF directory\fP.
An error occurred while positioning to the location of the
directory.
.PP
\fBWrong data type %d for field "%s"\fP.
The tag entry in the directory had an incorrect data type.
For example, an
.I ImageDescription
tag with a
.SM SHORT
data type.
.PP
\fBTIFF directory is missing required "%s" field\fP.
The specified tag is required to be present by the
.SM TIFF
5.0 specification, but is missing.
The directory is (usually) unusable.
.PP
\fB%s: Rational with zero denominator\fP.
A directory tag has a
.SM RATIONAL
value whose denominator is zero.
.PP
\fBIncorrect count %d for field "%s" (%lu, expecting %lu); tag ignored\fP.
The specified tag's count field is bad.
For example, a count other than 1 for a
.I SubFileType
tag.
.PP
\fBCannot handle different per-sample values for field "%s"\fP.
The tag has
.I SamplesPerPixel
values and they are not all the same; e.g.
.IR BitsPerSample .
The library is unable to handle images of this sort.
.PP
\fBCount mismatch for field "%s"; expecting %d, got %d\fP.
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.
.PP
\fBInvalid TIFF directory; tags are not sorted in ascending order\fP.
The directory tags are not properly sorted as specified
in the
.SM TIFF
5.0 specification.
This error is not fatal.
.PP
\fBIgnoring unknown field with tag %d (0x%x)\fP.
An unknown tag was encountered in the directory;
the library ignores all such tags.
.PP
\fBTIFF directory is missing requred "ImageLength" field\fP.
The image violates the specification by not having a necessary field.
There is no way for the library to recover from this error.
.PP
\fBTIFF directory is missing requred "PlanarConfig" field\fP.
The image violates the specification by not having a necessary field.
There is no way for the library to recover from this error.
.PP
\fBTIFF directory is missing requred "StripOffsets" field\fP.
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.
.PP
\fBTIFF directory is missing requred "TileOffsets" field\fP.
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.
.PP
\fBTIFF directory is missing required "StripByteCounts" field\fP.
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.
.PP
\fBTIFF directory is missing required "StripByteCounts" field, calculating from imagelength\fP.
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.
.PP
\fBBogus "StripByteCounts" field, ignoring and calculating from imagelength\fP.
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.
.SH "SEE ALSO"
.BR TIFFOpen (3TIFF),
.BR TIFFWriteDirectory (3TIFF),
.BR TIFFSetDirectory (3TIFF),
.BR TIFFSetSubDirectory (3TIFF),
.BR libtiff (3TIFF)
.PP
Libtiff library home page:
.BR http://www.remotesensing.org/libtiff/
Commit	Line	Data
	1	.\" $Id: TIFFReadDirectory.3tiff,v 1.2 2005/11/02 11:07:18 dron Exp $
	2	.\"
	3	.\" Copyright (c) 1988-1997 Sam Leffler
	4	.\" Copyright (c) 1991-1997 Silicon Graphics, Inc.
	5	.\"
	6	.\" Permission to use, copy, modify, distribute, and sell this software and
	7	.\" its documentation for any purpose is hereby granted without fee, provided
	8	.\" that (i) the above copyright notices and this permission notice appear in
	9	.\" all copies of the software and related documentation, and (ii) the names of
	10	.\" Sam Leffler and Silicon Graphics may not be used in any advertising or
	11	.\" publicity relating to the software without the specific, prior written
	12	.\" permission of Sam Leffler and Silicon Graphics.
	13	.\"
	14	.\" THE SOFTWARE IS PROVIDED "AS-IS" AND WITHOUT WARRANTY OF ANY KIND,
	15	.\" EXPRESS, IMPLIED OR OTHERWISE, INCLUDING WITHOUT LIMITATION, ANY
	16	.\" WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
	17	.\"
	18	.\" IN NO EVENT SHALL SAM LEFFLER OR SILICON GRAPHICS BE LIABLE FOR
	19	.\" ANY SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY KIND,
	20	.\" OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
	21	.\" WHETHER OR NOT ADVISED OF THE POSSIBILITY OF DAMAGE, AND ON ANY THEORY OF
	22	.\" LIABILITY, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
	23	.\" OF THIS SOFTWARE.
	24	.\"
	25	.if n .po 0
	26	.TH TIFFReadDirectory 3TIFF "October 15, 1995" "libtiff"
	27	.SH NAME
	28	TIFFReadDirectory \- get the contents of the next directory in an open
	29	.SM TIFF
	30	file
	31	.SH SYNOPSIS
	32	.B "#include <tiffio.h>"
	33	.sp
	34	.BI "int TIFFReadDirectory(TIFF *" tif ")"
	35	.SH DESCRIPTION
	36	Read the next directory in the specified file and make it the current
	37	directory. Applications only need to call
	38	.I TIFFReadDirectory
	39	to read multiple subfiles in a single
	40	.SM TIFF
	41	file\(em
	42	the first directory in a file is automatically read when
	43	.IR TIFFOpen
	44	is called.
	45	.SH NOTES
	46	If the library is compiled with
	47	.SM STRIPCHOP_SUPPORT
	48	enabled, then images that have a single uncompressed strip or tile of data are
	49	automatically treated as if they were made up of multiple strips or tiles of
	50	approximately 8 kilobytes each. This operation is done only in-memory; it does
	51	not alter the contents of the file. However, the construction of the ``chopped
	52	strips'' is visible to the application through the number of strips [tiles]
	53	returned by
	54	.I TIFFNumberOfStrips
	55	[\c
	56	.IR TIFFNumberOfTiles ].
	57	.SH "RETURN VALUES"
	58	If the next directory was successfully read, 1 is returned. Otherwise, 0 is
	59	returned if an error was encountered, or if there are no more directories to
	60	be read.
	61	.SH DIAGNOSTICS
	62	All error messages are directed to the
	63	.IR TIFFError (3TIFF)
	64	routine.
	65	All warning messages are directed to the
	66	.IR TIFFWarning (3TIFF)
	67	routine.
	68	.PP
	69	\fBSeek error accessing TIFF directory\fP.
	70	An error occurred while positioning to the location of the
	71	directory.
	72	.PP
	73	\fBWrong data type %d for field "%s"\fP.
	74	The tag entry in the directory had an incorrect data type.
	75	For example, an
	76	.I ImageDescription
	77	tag with a
	78	.SM SHORT
	79	data type.
	80	.PP
	81	\fBTIFF directory is missing required "%s" field\fP.
	82	The specified tag is required to be present by the
	83	.SM TIFF
	84	5.0 specification, but is missing.
	85	The directory is (usually) unusable.
	86	.PP
	87	\fB%s: Rational with zero denominator\fP.
	88	A directory tag has a
	89	.SM RATIONAL
	90	value whose denominator is zero.
	91	.PP
	92	\fBIncorrect count %d for field "%s" (%lu, expecting %lu); tag ignored\fP.
	93	The specified tag's count field is bad.
	94	For example, a count other than 1 for a
	95	.I SubFileType
	96	tag.
	97	.PP
	98	\fBCannot handle different per-sample values for field "%s"\fP.
	99	The tag has
	100	.I SamplesPerPixel
	101	values and they are not all the same; e.g.
	102	.IR BitsPerSample .
	103	The library is unable to handle images of this sort.
	104	.PP
	105	\fBCount mismatch for field "%s"; expecting %d, got %d\fP.
	106	The count field in a
	107	tag does not agree with the number expected by the library.
	108	This should never happen, so if it does, the library refuses to
	109	read the directory.
	110	.PP
	111	\fBInvalid TIFF directory; tags are not sorted in ascending order\fP.
	112	The directory tags are not properly sorted as specified
	113	in the
	114	.SM TIFF
	115	5.0 specification.
	116	This error is not fatal.
	117	.PP
	118	\fBIgnoring unknown field with tag %d (0x%x)\fP.
	119	An unknown tag was encountered in the directory;
	120	the library ignores all such tags.
	121	.PP
	122	\fBTIFF directory is missing requred "ImageLength" field\fP.
	123	The image violates the specification by not having a necessary field.
	124	There is no way for the library to recover from this error.
	125	.PP
	126	\fBTIFF directory is missing requred "PlanarConfig" field\fP.
	127	The image violates the specification by not having a necessary field.
	128	There is no way for the library to recover from this error.
	129	.PP
	130	\fBTIFF directory is missing requred "StripOffsets" field\fP.
	131	The image has multiple strips, but is missing the tag that
	132	specifies the file offset to each strip of data.
	133	There is no way for the library to recover from this error.
	134	.PP
	135	\fBTIFF directory is missing requred "TileOffsets" field\fP.
	136	The image has multiple tiles, but is missing the tag that
	137	specifies the file offset to each tile of data.
	138	There is no way for the library to recover from this error.
	139	.PP
	140	\fBTIFF directory is missing required "StripByteCounts" field\fP.
	141	The image has multiple strips, but is missing the tag that
	142	specifies the size of each strip of data.
	143	There is no way for the library to recover from this error.
	144	.PP
	145	\fBTIFF directory is missing required "StripByteCounts" field, calculating from imagelength\fP.
	146	The image violates the specification by not having a necessary field.
	147	However, when the image is comprised of only one strip or tile, the
	148	library will estimate the missing value based on the file size.
	149	.PP
	150	\fBBogus "StripByteCounts" field, ignoring and calculating from imagelength\fP.
	151	Certain vendors violate the specification by writing zero for
	152	the StripByteCounts tag when they want to leave the value
	153	unspecified.
	154	If the image has a single strip, the library will estimate
	155	the missing value based on the file size.
	156	.SH "SEE ALSO"
	157	.BR TIFFOpen (3TIFF),
	158	.BR TIFFWriteDirectory (3TIFF),
	159	.BR TIFFSetDirectory (3TIFF),
	160	.BR TIFFSetSubDirectory (3TIFF),
	161	.BR libtiff (3TIFF)
	162	.PP
	163	Libtiff library home page:
	164	.BR http://www.remotesensing.org/libtiff/