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Man Pages


Manual Reference Pages  -  LIBTIFF (3)

NAME

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

CONTENTS

Synopsis
Description
Diagnostics
Bugs

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;       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

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 calulcations 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 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/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 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: http://www.remotesensing.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.

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libtiff INTRO (3TIFF) November 2, 2005

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