TIFFReadDirectory.3tiff 6.0 KB

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  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
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  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
  121. \fBTIFF directory is missing required "ImageLength" field\fP.
  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
  125. \fBTIFF directory is missing required "PlanarConfig" field\fP.
  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
  129. \fBTIFF directory is missing required "StripOffsets" field\fP.
  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
  134. \fBTIFF directory is missing required "TileOffsets" field\fP.
  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.simplesystems.org/libtiff/