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 suit-
       able  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)  (decompres-
       sion  only), an experimental LZ-style algorithm known as
       Deflate (32946), and an experimental CIE LogLuv compres-
       sion  scheme designed for images with high dynamic range
       (32845 for LogL and 32845 for LogLuv).  Directory infor-
       mation  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 Signifi-
       cant 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 tsam-
       ple_t is limited by the 16-bit field used to  store  the
       SamplesPerPixel tag.  tdir_t constrains the maximum num-
       ber 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
       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 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 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-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.  Pos-
              sible values (independent bits that can  be  com-
              bined by or'ing them together) are: FAXMODE_CLAS-
              SIC (enable old-style format in which the RTC  is
              written  at  the  end  of  the  last strip), FAX-
              MODE_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 col-
              ormap 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 redun-
              dantly 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  JPEGCOL-
              ORMODE_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: JPEGTA-
              BLESMODE_QUANT (include quantization tables), and
              JPEGTABLESMODE_HUFF  (include  Huffman   encoding
              tables).     The   default   value   is   JPEGTA-
              BLESMODE_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  compres-
              sion  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: PIXARLOG-
              DATAFMT_8BIT for 8-bit unsigned pixels, PIXARLOG-
              DATAFMT_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,     PIXARLOG-
              DATAFMT_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  identi-
              cally   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: SGILOG-
              DATAFMT_FLTXYZ  for converting between LogLuv and
              32-bit IEEE floating valued XYZ  pixels,  SGILOG-
              DATAFMT_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 like-
       wise 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), tiff-
       split(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.

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.   The  library  discards  unknown  tags.  The
       library should do more validity  checking  of  a  direc-
       tory's contents.



libtiff                November 24, 2004           INTRO(3TIFF)
