Manpages - libtiff.3tiff

NAME
SYNOPSIS
DESCRIPTION
DATA TYPES
LIST OF ROUTINES
TAG USAGE
PSEUDO TAGS
DIAGNOSTICS
SEE ALSO
BUGS

NAME

libtiff - introduction to libtiff, a library for reading and writing

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),

1D Huffman compression (2),

Group 3 Facsimile compression (3),

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 (

) to Least Significant Bit (

) or

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

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

image. Likewise tsample_t is limited by the 16-bit field used to store the SamplesPerPixel tag. tdir_t constrains the maximum number of

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

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

  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 the

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

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/W	used 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 calculations
  YCbCrSubsampling	530	R/W
  YPosition	286	R/W
  YResolution	283	R/W	used by Group 3 codec

PSEUDO TAGS

In addition to the normal

tags the library supports a collection of tags whose values lie in a range outside the valid range of

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/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/W	compression quality level
  TIFFTAG_PIXARLOGDATAFMT	PixarLog	R/W	user data format
  TIFFTAG_PIXARLOGQUALITY	PixarLog	R/W	compression 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

is written at the end of the last strip), FAXMODE_NORTC (opposite of FAXMODE_CLASSIC; also called FAXMODE_CLASSF), FAXMODE_NOEOL (do not write

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.

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.