[wxWidgets.git] / src / tiff / man / TIFFReadDirectory.3tiff

.\"
.\" 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 required "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 required "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 required "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 required "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
8414a40c VZ	1	.\"
	2	.\" Copyright (c) 1988-1997 Sam Leffler
	3	.\" Copyright (c) 1991-1997 Silicon Graphics, Inc.
	4	.\"
	5	.\" Permission to use, copy, modify, distribute, and sell this software and
	6	.\" its documentation for any purpose is hereby granted without fee, provided
	7	.\" that (i) the above copyright notices and this permission notice appear in
	8	.\" all copies of the software and related documentation, and (ii) the names of
	9	.\" Sam Leffler and Silicon Graphics may not be used in any advertising or
	10	.\" publicity relating to the software without the specific, prior written
	11	.\" permission of Sam Leffler and Silicon Graphics.
	12	.\"
	13	.\" THE SOFTWARE IS PROVIDED "AS-IS" AND WITHOUT WARRANTY OF ANY KIND,
	14	.\" EXPRESS, IMPLIED OR OTHERWISE, INCLUDING WITHOUT LIMITATION, ANY
	15	.\" WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
	16	.\"
	17	.\" IN NO EVENT SHALL SAM LEFFLER OR SILICON GRAPHICS BE LIABLE FOR
	18	.\" ANY SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY KIND,
	19	.\" OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
	20	.\" WHETHER OR NOT ADVISED OF THE POSSIBILITY OF DAMAGE, AND ON ANY THEORY OF
	21	.\" LIABILITY, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
	22	.\" OF THIS SOFTWARE.
	23	.\"
	24	.if n .po 0
	25	.TH TIFFReadDirectory 3TIFF "October 15, 1995" "libtiff"
	26	.SH NAME
	27	TIFFReadDirectory \- get the contents of the next directory in an open
	28	.SM TIFF
	29	file
	30	.SH SYNOPSIS
	31	.B "#include <tiffio.h>"
	32	.sp
	33	.BI "int TIFFReadDirectory(TIFF *" tif ")"
	34	.SH DESCRIPTION
	35	Read the next directory in the specified file and make it the current
	36	directory. Applications only need to call
	37	.I TIFFReadDirectory
	38	to read multiple subfiles in a single
	39	.SM TIFF
	40	file\(em
	41	the first directory in a file is automatically read when
	42	.IR TIFFOpen
	43	is called.
	44	.SH NOTES
	45	If the library is compiled with
	46	.SM STRIPCHOP_SUPPORT
	47	enabled, then images that have a single uncompressed strip or tile of data are
	48	automatically treated as if they were made up of multiple strips or tiles of
	49	approximately 8 kilobytes each. This operation is done only in-memory; it does
	50	not alter the contents of the file. However, the construction of the ``chopped
	51	strips'' is visible to the application through the number of strips [tiles]
	52	returned by
	53	.I TIFFNumberOfStrips
	54	[\c
	55	.IR TIFFNumberOfTiles ].
	56	.SH "RETURN VALUES"
	57	If the next directory was successfully read, 1 is returned. Otherwise, 0 is
	58	returned if an error was encountered, or if there are no more directories to
	59	be read.
	60	.SH DIAGNOSTICS
	61	All error messages are directed to the
	62	.IR TIFFError (3TIFF)
	63	routine.
	64	All warning messages are directed to the
65	.IR TIFFWarning (3TIFF)
66	routine.
67	.PP
68	\fBSeek error accessing TIFF directory\fP.
69	An error occurred while positioning to the location of the
70	directory.
71	.PP
72	\fBWrong data type %d for field "%s"\fP.
73	The tag entry in the directory had an incorrect data type.
74	For example, an
75	.I ImageDescription
76	tag with a
77	.SM SHORT
78	data type.
79	.PP
80	\fBTIFF directory is missing required "%s" field\fP.
81	The specified tag is required to be present by the
82	.SM TIFF
83	5.0 specification, but is missing.
84	The directory is (usually) unusable.
85	.PP
86	\fB%s: Rational with zero denominator\fP.
87	A directory tag has a
88	.SM RATIONAL
89	value whose denominator is zero.
90	.PP
91	\fBIncorrect count %d for field "%s" (%lu, expecting %lu); tag ignored\fP.
92	The specified tag's count field is bad.
93	For example, a count other than 1 for a
94	.I SubFileType
95	tag.
96	.PP
97	\fBCannot handle different per-sample values for field "%s"\fP.
98	The tag has
99	.I SamplesPerPixel
100	values and they are not all the same; e.g.
101	.IR BitsPerSample .
102	The library is unable to handle images of this sort.
103	.PP
104	\fBCount mismatch for field "%s"; expecting %d, got %d\fP.
105	The count field in a
106	tag does not agree with the number expected by the library.
107	This should never happen, so if it does, the library refuses to
108	read the directory.
109	.PP
110	\fBInvalid TIFF directory; tags are not sorted in ascending order\fP.
111	The directory tags are not properly sorted as specified
112	in the
113	.SM TIFF
114	5.0 specification.
115	This error is not fatal.
116	.PP
117	\fBIgnoring unknown field with tag %d (0x%x)\fP.
118	An unknown tag was encountered in the directory;
119	the library ignores all such tags.
120	.PP
80ed523f	121	\fBTIFF directory is missing required "ImageLength" field\fP.
8414a40c VZ	122	The image violates the specification by not having a necessary field.
	123	There is no way for the library to recover from this error.
	124	.PP
80ed523f	125	\fBTIFF directory is missing required "PlanarConfig" field\fP.
8414a40c VZ	126	The image violates the specification by not having a necessary field.
	127	There is no way for the library to recover from this error.
	128	.PP
80ed523f	129	\fBTIFF directory is missing required "StripOffsets" field\fP.
8414a40c VZ	130	The image has multiple strips, but is missing the tag that
	131	specifies the file offset to each strip of data.
	132	There is no way for the library to recover from this error.
	133	.PP
80ed523f	134	\fBTIFF directory is missing required "TileOffsets" field\fP.
8414a40c VZ	135	The image has multiple tiles, but is missing the tag that
	136	specifies the file offset to each tile of data.
	137	There is no way for the library to recover from this error.
	138	.PP
	139	\fBTIFF directory is missing required "StripByteCounts" field\fP.
	140	The image has multiple strips, but is missing the tag that
	141	specifies the size of each strip of data.
	142	There is no way for the library to recover from this error.
	143	.PP
	144	\fBTIFF directory is missing required "StripByteCounts" field, calculating from imagelength\fP.
	145	The image violates the specification by not having a necessary field.
	146	However, when the image is comprised of only one strip or tile, the
	147	library will estimate the missing value based on the file size.
	148	.PP
	149	\fBBogus "StripByteCounts" field, ignoring and calculating from imagelength\fP.
	150	Certain vendors violate the specification by writing zero for
	151	the StripByteCounts tag when they want to leave the value
	152	unspecified.
	153	If the image has a single strip, the library will estimate
	154	the missing value based on the file size.
	155	.SH "SEE ALSO"
	156	.BR TIFFOpen (3TIFF),
	157	.BR TIFFWriteDirectory (3TIFF),
	158	.BR TIFFSetDirectory (3TIFF),
	159	.BR TIFFSetSubDirectory (3TIFF),
	160	.BR libtiff (3TIFF)
	161	.PP
	162	Libtiff library home page:
	163	.BR http://www.remotesensing.org/libtiff/