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INTRO(3TIFF) INTRO(3TIFF)
NAME
libtiff - introduction to libtiff, a library for reading and writing
TIFF 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 the
TIFF format. The following typedefs are exposed to users either
through function definitions or through parameters passed through the
varargs interfaces.
typedef unsigned short uint16_t; 16-bit unsigned integer
typedef unsigned <thing> uint32_t; 32-bit unsigned integer
typedef unsigned int ttag_t; directory tag
typedef uint16_t tdir_t; directory index
typedef uint16_t tsample_t; sample number
typedef uint32_t tstrip_t; strip number
typedef uint32_t ttile_t; tile number
typedef int32_t tsize_t; i/o size in bytes
typedef void* tdata_t; image data ref
typedef void* thandle_t; client data handle
typedef int32_t 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_t 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
TIFFCheckpointDirectorywrites 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 the TIFF 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/WLibrary Use/Notes
Artist 315 R/W
BadFaxLines 326 R/W
BitsPerSample 258 R/Wlots
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/Wchoosing codec
ConsecutiveBadFaxLines 328R/W
Copyright 33432 R/W
DataType 32996 Robsoleted by SampleFormat tag
DateTime 306 R/W
DocumentName 269 R/W
DotRange 336 R/W
ExtraSamples 338 R/Wlots
FaxRecvParams 34908 R/W
FaxSubAddress 34909 R/W
FaxRecvTime 34910 R/W
FillOrder 266 R/Wcontrol 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/Wused by Group 3 codec
Group4Options 293 R/W
HostComputer 316 R/W
ImageDepth 32997 R/Wtile/strip calculations
ImageDescription 270 R/W
ImageLength 257 R/Wlots
ImageWidth 256 R/Wlots
InkNames 333 R/W
InkSet 332 R/W
JPEGTables 347 R/Wused by JPEG codec
Make 271 R/W
Matteing 32995 Robsoleted by ExtraSamples tag
MaxSampleValue 281 R/W
MinSampleValue 280 R/W
Model 272 R/W
NewSubFileType 254 R/Wcalled SubFileType in spec
NumberOfInks 334 R/W
Orientation 274 R/W
PageName 285 R/W
PageNumber 297 R/W
PhotometricInterpretation 262R/Wused by Group 3 and JPEG codecs
PlanarConfiguration 284 R/Wdata i/o
Predictor 317 R/Wused by LZW and Deflate codecs
PrimaryChromacities 319 R/W
ReferenceBlackWhite 532 R/W
ResolutionUnit 296 R/Wused by Group 3 codec
RowsPerStrip 278 R/Wdata i/o
SampleFormat 339 R/W
SamplesPerPixel 277 R/Wlots
SMinSampleValue 340 R/W
SMaxSampleValue 341 R/W
Software 305 R/W
StoNits 37439 R/W
StripByteCounts 279 R/Wdata i/o
StripOffsets 273 R/Wdata i/o
SubFileType 255 R/Wcalled OSubFileType in spec
TargetPrinter 337 R/W
Thresholding 263 R/W
TileByteCounts 324 R/Wdata i/o
TileDepth 32998 R/Wtile/strip calculations
TileLength 323 R/Wdata i/o
TileOffsets 324 R/Wdata i/o
TileWidth 322 R/Wdata i/o
TransferFunction 301 R/W
WhitePoint 318 R/W
XPosition 286 R/W
XResolution 282 R/W
YCbCrCoefficients 529 R/Wused by TIFFRGBAImage support
YCbCrPositioning 531 R/Wtile/strip size calculations
YCbCrSubsampling 530 R/W
YPosition 286 R/W
YResolution 283 R/Wused by Group 3 codec
PSEUDO TAGS
In addition to the normal TIFF 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 pseudo-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/WLibrary Use/Notes
TIFFTAG_FAXMODE G3 R/Wgeneral codec operation
TIFFTAG_FAXFILLFUNC G3/G4 R/Wbitmap fill function
TIFFTAG_JPEGQUALITY JPEG R/Wcompression quality control
TIFFTAG_JPEGCOLORMODE JPEG R/Wcontrol colorspace conversions
TIFFTAG_JPEGTABLESMODE JPEGR/Wcontrol contents of JPEGTables tag
TIFFTAG_ZIPQUALITY Deflate R/Wcompression quality level
TIFFTAG_PIXARLOGDATAFMT PixarLogR/Wuser data format
TIFFTAG_PIXARLOGQUALITY PixarLogR/Wcompression quality level
TIFFTAG_SGILOGDATAFMT SGILog R/Wuser 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 RTC
is written at the end of the last strip), FAXMODE_NORTC
(opposite of FAXMODE_CLASSIC; also called FAXMODE_CLASSF),
FAXMODE_NOEOL (do not write EOL codes 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 contains 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: http://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.
libtiff November 2, 2005 INTRO(3TIFF)