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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 com-
       pression (1), CCITT 1D Huffman compression (2), CCITT Group 3 Facsimile compression (3), CCITT Group 4  Facsim-
       ile 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 Sam-
       plesPerPixel tag.  tdir_t constrains the maximum number of IFDs that may appear in an image and may be an arbi-
       trary 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
       TIFFFileName             return name of open file
       TIFFFileno               return open file descriptor
       TIFFFindCODEC            find standard codec for the specific scheme
       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 Com-
       pression 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 com-
       pression 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 normal TIFF tags the library supports a collection of tags whose values lie in a range  out-
       side the valid range of TIFF tags.  These tags are termed pseud-tags and are used to control various codec-spe-
       cific 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 RTC is written at the
              end of the last strip), FAXMODE_NORTC (opposite of FAXMODE_CLASSIC; also  called  FAXMODE_CLASSF),  FAX-
              MODE_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: JPEG-
              COLORMODE_RAW (do not convert), and JPEGCOLORMODE_RGB (convert to/from RGB) The default value  is  JPEG-
              COLORMODE_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  JPEGTA-
              BLESMODE_HUFF  (include  Huffman  encoding  tables).   The default value is JPEGTABLESMODE_QUANT|JPEGTA-
              BLESMODE_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, PIXAR-
              LOGDATAFMT_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  SGILOG-
              DATAFMT_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), tiffs-
       plit(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.



libtiff                        November 2, 2005                   INTRO(3TIFF)