libtiff (3)
Leading comments
$Id: libtiff.3tiff,v 1.5 2016-09-25 20:05:51 bfriesen 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 ...
NAME
libtiff - introduction to libtiff, a library for reading and writingTIFF
files
SYNOPSIS
#include <tiffio.h>cc file.c -ltiff
DESCRIPTION
libtiff is a library for reading and writing data files encoded with the Tag Image File format, Revision 6.0 (or revision 5.0 or revision 4.0). This file format is suitable for archiving multi-color and monochromatic image data.The library supports several compression algorithms, as indicated by the Compression field, including: no compression (1),
CCITT
1D Huffman compression (2),
CCITT
Group 3 Facsimile compression (3),
CCITT
Group 4 Facsimile compression (4),
Lempel-Ziv & Welch compression (5),
baseline JPEG compression (7),
word-aligned 1D Huffman compression (32771),
and
PackBits compression (32773).
In addition, several nonstandard compression algorithms are supported: the
4-bit compression algorithm used by the
ThunderScan
program (32809) (decompression only), NeXT's 2-bit compression algorithm
(32766) (decompression only), an experimental LZ-style algorithm known as
Deflate (32946), and an experimental CIE LogLuv compression scheme designed
for images with high dynamic range (32845 for LogL and 32845 for LogLuv).
Directory information may be in either little- or big-endian byte order-byte
swapping is automatically done by the library. Data bit ordering may be either
Most Significant Bit (MSB
) to Least Significant Bit (LSB
) or
LSB
to
MSB.
Finally, the library does not support files in which the
BitsPerSample,
Compression,
MinSampleValue,
or
MaxSampleValue
fields are defined differently on a per-sample basis
(in Rev. 6.0 the
Compression
tag is not defined on a per-sample basis, so this is immaterial).
DATA TYPES
The library makes extensive use of C typedefs to promote portability. Two sets of typedefs are used, one for communication with clients of the library and one for internal data structures and parsing of theTIFF
format.
The following typedefs are exposed to users either through function
definitions or through parameters passed through the varargs interfaces.
typedef unsigned short uint16; 16-bit unsigned integer typedef unsigned <thing> uint32; 32-bit unsigned integer typedef unsigned int ttag_t; directory tag typedef uint16 tdir_t; directory index typedef uint16 tsample_t; sample number typedef uint32 tstrip_t; strip number typedef uint32 ttile_t; tile number typedef int32 tsize_t; i/o size in bytes typedef void* tdata_t; image data ref typedef void* thandle_t; client data handle typedef int32 toff_t; file offset
Note that tstrip_t, ttile_t, and tsize_t are constrained to be no more than 32-bit quantities by 32-bit fields they are stored in in the
TIFF
image.
Likewise
tsample_t
is limited by the 16-bit field used to store the
SamplesPerPixel
tag.
tdir_t
constrains the maximum number of
IFDs
that may appear in an image and may be an arbitrary size (w/o penalty).
ttag_t
must be either int, unsigned int, pointer, or double because the library uses
a varargs interface and
ANSI C
restricts the type of the parameter before an ellipsis to be a promoted type.
toff_t
is defined as int32 because TIFF file offsets are (unsigned) 32-bit
quantities. A signed value is used because some interfaces return -1 on
error. Finally, note that user-specified data references are passed as opaque
handles and only cast at the lowest layers where their type is presumed.
LIST OF ROUTINES
The following routines are part of the library. Consult specific manual pages for details on their operation; on most systems doing ``man function-name'' will work.
Name Description
TIFFCheckpointDirectory writes the current state of the directory
TIFFCheckTile very x,y,z,sample is within image
TIFFCIELabToRGBInit initialize CIE L*a*b* 1976 to RGB conversion state
TIFFCIELabToXYZ perform CIE L*a*b* 1976 to CIE XYZ conversion
TIFFClientOpen open a file for reading or writing
TIFFClose close an open file
TIFFComputeStrip return strip containing y,sample
TIFFComputeTile return tile containing x,y,z,sample
TIFFCurrentDirectory return index of current directory
TIFFCurrentRow return index of current scanline
TIFFCurrentStrip return index of current strip
TIFFCurrentTile return index of current tile
TIFFDataWidth return the size of TIFF data types
TIFFError library error handler
TIFFFdOpen open a file for reading or writing
TIFFFieldDataType get data type from field information
TIFFFieldName get field name from field information
TIFFFieldPassCount get whether to pass a value count to Get/SetField
TIFFFieldReadCount get number of values to be read from field
TIFFFieldTag get tag value from field information
TIFFFieldWithName get field information given field name
TIFFFieldWithTag get field information given tag
TIFFFieldWriteCount get number of values to be written to field
TIFFFileName return name of open file
TIFFFileno return open file descriptor
TIFFFindCODEC find standard codec for the specific scheme
TIFFFindField get field information given tag and data type
TIFFFlush flush all pending writes
TIFFFlushData flush pending data writes
TIFFGetBitRevTable return bit reversal table
TIFFGetField return tag value in current directory
TIFFGetFieldDefaulted return tag value in current directory
TIFFGetMode return open file mode
TIFFGetVersion return library version string
TIFFIsCODECConfigured check, whether we have working codec
TIFFIsMSB2LSB return true if image data is being returned
with bit 0 as the most significant bit
TIFFIsTiled return true if image data is tiled
TIFFIsByteSwapped return true if image data is byte-swapped
TIFFNumberOfStrips return number of strips in an image
TIFFNumberOfTiles return number of tiles in an image
TIFFOpen open a file for reading or writing
TIFFPrintDirectory print description of the current directory
TIFFReadBufferSetup specify i/o buffer for reading
TIFFReadDirectory read the next directory
TIFFReadEncodedStrip read and decode a strip of data
TIFFReadEncodedTile read and decode a tile of data
TIFFReadRawStrip read a raw strip of data
TIFFReadRawTile read a raw tile of data
TIFFReadRGBAImage read an image into a fixed format raster
TIFFReadScanline read and decode a row of data
TIFFReadTile read and decode a tile of data
TIFFRegisterCODEC override standard codec for the specific scheme
TIFFReverseBits reverse bits in an array of bytes
TIFFRGBAImageBegin setup decoder state for TIFFRGBAImageGet
TIFFRGBAImageEnd release TIFFRGBAImage decoder state
TIFFRGBAImageGet read and decode an image
TIFFRGBAImageOK is image readable by TIFFRGBAImageGet
TIFFScanlineSize return size of a scanline
TIFFSetDirectory set the current directory
TIFFSetSubDirectory set the current directory
TIFFSetErrorHandler set error handler function
TIFFSetField set a tag's value in the current directory
TIFFSetWarningHandler set warning handler function
TIFFStripSize returns size of a strip
TIFFRawStripSize returns the number of bytes in a raw strip
TIFFSwabShort swap bytes of short
TIFFSwabLong swap bytes of long
TIFFSwabArrayOfShort swap bytes of an array of shorts
TIFFSwabArrayOfLong swap bytes of an array of longs
TIFFTileRowSize return size of a row in a tile
TIFFTileSize return size of a tile
TIFFUnRegisterCODEC unregisters the codec
TIFFVGetField return tag value in current directory
TIFFVGetFieldDefaulted return tag value in current directory
TIFFVSetField set a tag's value in the current directory
TIFFVStripSize returns the number of bytes in a strip
TIFFWarning library warning handler
TIFFWriteDirectory write the current directory
TIFFWriteEncodedStrip compress and write a strip of data
TIFFWriteEncodedTile compress and write a tile of data
TIFFWriteRawStrip write a raw strip of data
TIFFWriteRawTile write a raw tile of data
TIFFWriteScanline write a scanline of data
TIFFWriteTile compress and write a tile of data
TIFFXYZToRGB perform CIE XYZ to RGB conversion
TIFFYCbCrToRGBInit initialize YCbCr to RGB conversion state
TIFFYCbCrtoRGB perform YCbCr to RGB conversion
Auxiliary functions:
_TIFFfree free memory buffer
_TIFFmalloc dynamically allocate memory buffer
_TIFFmemcmp compare contents of the memory buffers
_TIFFmemcpy copy contents of the one buffer to another
_TIFFmemset fill memory buffer with a constant byte
_TIFFrealloc dynamically reallocate memory buffer
TAG USAGE
The table below lists theTIFF
tags that are recognized and handled by the library.
If no use is indicated in the table, then the library
reads and writes the tag, but does not use it internally.
Note that some tags are meaningful only when a particular
compression scheme is being used; e.g.
Group3Options
is only useful if
Compression
is set to
CCITT
Group 3 encoding.
Tags of this sort are considered
codec-specific
tags and the library does not recognize them except when the
Compression
tag has been previously set to the relevant compression scheme.
Tag Name Value R/W Library Use/Notes Artist 315 R/W BadFaxLines 326 R/W BitsPerSample 258 R/W lots CellLength 265 parsed but ignored CellWidth 264 parsed but ignored CleanFaxData 327 R/W ColorMap 320 R/W ColorResponseUnit 300 parsed but ignored Compression 259 R/W choosing codec ConsecutiveBadFaxLines 328 R/W Copyright 33432 R/W DataType 32996 R obsoleted by SampleFormat tag DateTime 306 R/W DocumentName 269 R/W DotRange 336 R/W ExtraSamples 338 R/W lots FaxRecvParams 34908 R/W FaxSubAddress 34909 R/W FaxRecvTime 34910 R/W FillOrder 266 R/W control bit order FreeByteCounts 289 parsed but ignored FreeOffsets 288 parsed but ignored GrayResponseCurve 291 parsed but ignored GrayResponseUnit 290 parsed but ignored Group3Options 292 R/W used by Group 3 codec Group4Options 293 R/W HostComputer 316 R/W ImageDepth 32997 R/W tile/strip calculations ImageDescription 270 R/W ImageLength 257 R/W lots ImageWidth 256 R/W lots InkNames 333 R/W InkSet 332 R/W JPEGTables 347 R/W used by JPEG codec Make 271 R/W Matteing 32995 R obsoleted by ExtraSamples tag MaxSampleValue 281 R/W MinSampleValue 280 R/W Model 272 R/W NewSubFileType 254 R/W called SubFileType in spec NumberOfInks 334 R/W Orientation 274 R/W PageName 285 R/W PageNumber 297 R/W PhotometricInterpretation 262 R/Wused by Group 3 and JPEG codecs PlanarConfiguration 284 R/W data i/o Predictor 317 R/W used by LZW and Deflate codecs PrimaryChromacities 319 R/W ReferenceBlackWhite 532 R/W ResolutionUnit 296 R/W used by Group 3 codec RowsPerStrip 278 R/W data i/o SampleFormat 339 R/W SamplesPerPixel 277 R/W lots SMinSampleValue 340 R/W SMaxSampleValue 341 R/W Software 305 R/W StoNits 37439 R/W StripByteCounts 279 R/W data i/o StripOffsets 273 R/W data i/o SubFileType 255 R/W called OSubFileType in spec TargetPrinter 337 R/W Thresholding 263 R/W TileByteCounts 324 R/W data i/o TileDepth 32998 R/W tile/strip calculations TileLength 323 R/W data i/o TileOffsets 324 R/W data i/o TileWidth 322 R/W data i/o TransferFunction 301 R/W WhitePoint 318 R/W XPosition 286 R/W XResolution 282 R/W YCbCrCoefficients 529 R/W used by TIFFRGBAImage support YCbCrPositioning 531 R/W tile/strip size calulcations YCbCrSubsampling 530 R/W YPosition 286 R/W YResolution 283 R/W used by Group 3 codec
PSEUDO TAGS
In addition to the normalTIFF
tags the library supports a collection of
tags whose values lie in a range outside the valid range of
TIFF
tags.
These tags are termed
pseud-tags
and are used to control various codec-specific functions within the library.
The table below summarizes the defined pseudo-tags.
Tag Name Codec R/W Library Use/Notes TIFFTAG_FAXMODE G3 R/W general codec operation TIFFTAG_FAXFILLFUNC G3/G4 R/W bitmap fill function TIFFTAG_JPEGQUALITY JPEG R/W compression quality control TIFFTAG_JPEGCOLORMODE JPEG R/W control colorspace conversions TIFFTAG_JPEGTABLESMODE JPEG R/W control contents of JPEGTables tag TIFFTAG_ZIPQUALITY Deflate R/Wcompression quality level TIFFTAG_PIXARLOGDATAFMT PixarLog R/Wuser data format TIFFTAG_PIXARLOGQUALITY PixarLog R/Wcompression quality level TIFFTAG_SGILOGDATAFMT SGILog R/W user data format
- TIFFTAG_FAXMODE
-
Control the operation of the Group 3 codec.
Possible values (independent bits that can be combined by
or'ing them together) are:
FAXMODE_CLASSIC
(enable old-style format in which the
RTCis written at the end of the last strip), FAXMODE_NORTC (opposite of FAXMODE_CLASSIC; also called FAXMODE_CLASSF), FAXMODE_NOEOL (do not writeEOLcodes at the start of each row of data), FAXMODE_BYTEALIGN (align each encoded row to an 8-bit boundary), FAXMODE_WORDALIGN (align each encoded row to an 16-bit boundary), The default value is dependent on the compression scheme; this pseudo-tag is used by the various G3 and G4 codecs to share code.
- TIFFTAG_FAXFILLFUNC
- Control the function used to convert arrays of black and white runs to packed bit arrays. This hook can be used to image decoded scanlines in multi-bit depth rasters (e.g. for display in colormap mode) or for other purposes. The default value is a pointer to a builtin function that images packed bilevel data.
- TIFFTAG_IPTCNEWSPHOTO
- Tag contaings image metadata per the IPTC newsphoto spec: Headline, captioning, credit, etc... Used by most wire services.
- TIFFTAG_PHOTOSHOP
- Tag contains Photoshop captioning information and metadata. Photoshop uses in parallel and redundantly alongside IPTCNEWSPHOTO information.
- TIFFTAG_JPEGQUALITY
- Control the compression quality level used in the baseline algorithm. Note that quality levels are in the range 0-100 with a default value of 75.
- TIFFTAG_JPEGCOLORMODE
- Control whether or not conversion is done between RGB and YCbCr colorspaces. Possible values are: JPEGCOLORMODE_RAW (do not convert), and JPEGCOLORMODE_RGB (convert to/from RGB) The default value is JPEGCOLORMODE_RAW.
- TIFFTAG_JPEGTABLESMODE
- Control the information written in the JPEGTables tag. Possible values (independent bits that can be combined by or'ing them together) are: JPEGTABLESMODE_QUANT (include quantization tables), and JPEGTABLESMODE_HUFF (include Huffman encoding tables). The default value is JPEGTABLESMODE_QUANT|JPEGTABLESMODE_HUFF.
- TIFFTAG_ZIPQUALITY
- Control the compression technique used by the Deflate codec. Quality levels are in the range 1-9 with larger numbers yielding better compression at the cost of more computation. The default quality level is 6 which yields a good time-space tradeoff.
- TIFFTAG_PIXARLOGDATAFMT
- Control the format of user data passed in to the PixarLog codec when encoding and passed out from when decoding. Possible values are: PIXARLOGDATAFMT_8BIT for 8-bit unsigned pixels, PIXARLOGDATAFMT_8BITABGR for 8-bit unsigned ABGR-ordered pixels, PIXARLOGDATAFMT_11BITLOG for 11-bit log-encoded raw data, PIXARLOGDATAFMT_12BITPICIO for 12-bit PICIO-compatible data, PIXARLOGDATAFMT_16BIT for 16-bit signed samples, and PIXARLOGDATAFMT_FLOAT for 32-bit IEEE floating point samples.
- TIFFTAG_PIXARLOGQUALITY
- Control the compression technique used by the PixarLog codec. This value is treated identically to TIFFTAG_ZIPQUALITY; see the above description.
- TIFFTAG_SGILOGDATAFMT
- Control the format of client data passed in to the SGILog codec when encoding and passed out from when decoding. Possible values are: SGILOGDATAFMT_FLTXYZ for converting between LogLuv and 32-bit IEEE floating valued XYZ pixels, SGILOGDATAFMT_16BITLUV for 16-bit encoded Luv pixels, SGILOGDATAFMT_32BITRAW and SGILOGDATAFMT_24BITRAW for no conversion of data, SGILOGDATAFMT_8BITRGB for returning 8-bit RGB data (valid only when decoding LogLuv-encoded data), SGILOGDATAFMT_FLTY for converting between LogL and 32-bit IEEE floating valued Y pixels, SGILOGDATAFMT_16BITL for 16-bit encoded L pixels, and SGILOGDATAFMT_8BITGRY for returning 8-bit greyscale data (valid only when decoding LogL-encoded data).
DIAGNOSTICS
All error messages are directed through the TIFFError routine. By default messages are directed to stderr in the form: module: message\n. Warning messages are likewise directed through the TIFFWarning routine.SEE ALSO
fax2tiff(1), gif2tiff(1), pal2rgb(1), ppm2tiff(1), rgb2ycbcr(1), ras2tiff(1), raw2tiff(1), sgi2tiff(1), tiff2bw(1), tiffdither(1), tiffdump(1), tiffcp(1), tiffcmp(1), tiffgt(1), tiffinfo(1), tiffmedian(1), tiffsplit(1), tiffsv(1).Tag Image File Format Specification --- Revision 6.0, an Aldus Technical Memorandum.
The Spirit of TIFF Class F, an appendix to the TIFF 5.0 specification prepared by Cygnet Technologies.
Libtiff library home page: www.simplesystems.org/libtiff
BUGS
The library does not support multi-sample images where some samples have different bits/sample.The library does not support random access to compressed data that is organized with more than one row per tile or strip.