TIFFSetField  -  set  the value(s) of a tag in a TIFF file
       open for writing


SYNOPSIS

       #include <tiffio.h>
       int TIFFSetField(TIFF* tif, ttag_t tag, ...)
       #include <stdarg.h>
       int TIFFVSetField(TIFF* tif, ttag_t tag, va_list ap)


DESCRIPTION

       TIFFSetField sets the value of a field  or  pseudo-tag  in
       the  current  directory associated with the open TIFF file
       tif.  (A pseudo-tag is a parameter that is used to control
       the  operation  of the TIFF library but whose value is not
       read or written to the underlying file.)  To set the value
       of  a  field the file must have been previously opened for
       writing with TIFFOpen(3T); pseudo-tags can be set  whether
       the  file was opened for reading or writing.  The field is
       identified by tag,  one  of  the  values  defined  in  the
       include  file  tiff.h  (see  also  the  table below).  The
       actual value is specified using a variable argument  list,
       as  prescribed  by  the  stdarg(3)  interface (or, on some
       machines, the varargs(3) interface.)

       TIFFVSetField is functionally equivalent  to  TIFFSetField
       except  that  it  takes  a  pointer to a variable argument
       list.  TIFFVSetField is useful for writing  routines  that
       are  layered on top of the functionality provided by TIFF­
       SetField.

       The tags understood by libtiff, the  number  of  parameter
       values,  and  the  expected types for the parameter values
       are shown below.  The data types are: char* is null-termi­
       nated  string  and  corresponds  to  the  ASCII data type;
       uint16 is an unsigned 16-bit value; uint32 is an  unsigned
       32-bit  value; uint16* is an array of unsigned 16-bit val­
       ues.  void* is an array  of  data  values  of  unspecified
       type.

       Consult  the  TIFF  specification  for  information on the
       meaning of each tag.

       Tag Name                        Count  Types             Notes
       TIFFTAG_ARTIST                  1      char*
       TIFFTAG_BADFAXLINES             1      uint32
       TIFFTAG_BITSPERSAMPLE           1      uint16
       TIFFTAG_CLEANFAXDATA            1      uint16
       TIFFTAG_COLORMAP                3      uint16*           1<<BitsPerSample arrays
       TIFFTAG_COMPRESSION             1      uint16
       TIFFTAG_CONSECUTIVEBADFAXLINES  1      uint32
       TIFFTAG_DATETIME                1      char*
       TIFFTAG_DOCUMENTNAME            1      char*
       TIFFTAG_DOTRANGE                2      uint16

       TIFFTAG_FAXMODE                 1      int                G3/G4 compression pseudo-tag
       TIFFTAG_FAXFILLFUNC             1      TIFFFaxFillFunc   G3/G4 compression pseudo-tag
       TIFFTAG_FILLORDER               1      uint16
       TIFFTAG_GROUP3OPTIONS           1      uint32
       TIFFTAG_GROUP4OPTIONS           1      uint32
       TIFFTAG_HALFTONEHINTS           2      uint16
       TIFFTAG_HOSTCOMPUTER            1      char*
       TIFFTAG_IMAGEDESCRIPTION        1      char*
       TIFFTAG_IMAGEDEPTH              1      uint32
       TIFFTAG_IMAGELENGTH             1      uint32
       TIFFTAG_IMAGEWIDTH              1      uint32
       TIFFTAG_INKNAMES                1      char*
       TIFFTAG_INKSET                  1      uint16
       TIFFTAG_JPEGTABLES              2      uint32*,void*      count & tables
       TIFFTAG_JPEGQUALITY             1      int               JPEG pseudo-tag
       TIFFTAG_JPEGCOLORMODE           1      int                JPEG pseudo-tag
       TIFFTAG_JPEGTABLESMODE          1      int                JPEG pseudo-tag
       TIFFTAG_MAKE                    1      char*
       TIFFTAG_MATTEING                1      uint16
       TIFFTAG_MAXSAMPLEVALUE          1      uint16
       TIFFTAG_MINSAMPLEVALUE          1      uint16
       TIFFTAG_MODEL                   1      char*
       TIFFTAG_ORIENTATION             1      uint16
       TIFFTAG_PAGENAME                1      char*
       TIFFTAG_PAGENUMBER              2      uint16
       TIFFTAG_PHOTOMETRIC             1      uint16
       TIFFTAG_PLANARCONFIG            1      uint16
       TIFFTAG_PREDICTOR               1      uint16
       TIFFTAG_PRIMARYCHROMATICITIES   1      float*            6-entry array
       TIFFTAG_REFERENCEBLACKWHITE     1      float*             2*SamplesPerPixel array
       TIFFTAG_RESOLUTIONUNIT          1      uint16
       TIFFTAG_ROWSPERSTRIP            1      uint32             must be > 0
       TIFFTAG_SAMPLEFORMAT            1      uint16
       TIFFTAG_SAMPLESPERPIXEL         1      uint16             value must be <= 4
       TIFFTAG_SMAXSAMPLEVALUE         1      double
       TIFFTAG_SMINSAMPLEVALUE         1      double
       TIFFTAG_SOFTWARE                1      char*
       TIFFTAG_STONITS                 1      double
       TIFFTAG_SUBFILETYPE             1      uint32
       TIFFTAG_SUBIFD                  2      uint16,uint32*    count & offsets array
       TIFFTAG_TARGETPRINTER           1      char*
       TIFFTAG_THRESHHOLDING           1      uint16
       TIFFTAG_TILEDEPTH               1      uint32
       TIFFTAG_TILELENGTH              1      uint32             must be a multiple of 8
       TIFFTAG_TILEWIDTH               1      uint32             must be a multiple of 8
       TIFFTAG_TRANSFERFUNCTION        1 or 3                   uint16*1<<BitsPerSample entry arrays
       TIFFTAG_XPOSITION               1      float
       TIFFTAG_XRESOLUTION             1      float
       TIFFTAG_WHITEPOINT              1      float*            2-entry array
       TIFFTAG_YCBCRCOEFFICIENTS       1      float*             3-entry array
       TIFFTAG_YCBCRPOSITIONING        1      uint16
       TIFFTAG_YCBCRSAMPLING           2      uint16
       TIFFTAG_YPOSITION               1      float

       TIFFTAG_ICCPROFILE              2      uint32,void*      count, profile data*
        Tag may not have its values changed once data is written.
        If SamplesPerPixel is one, then a single array is passed;
       otherwise three arrays should be passed.
       * The contents of this field are quite complex.   See  The
       ICC Profile Format Specification, Annex B.3 "Embedding ICC
       Profiles     in     TIFF     Files"     (available      at
       http://www.color.org) for an explanation.


RETURN VALUES

       1  is returned if the tag is defined in the current direc­
       tory; otherwise a 0 is returned.


RETURN VALUES

       1 is returned if the operation was successful.  Otherwise,
       0 is returned if an error was detected.


DIAGNOSTICS

       All  error messages are directed to the TIFFError(3T) rou­
       tine.

       %s: Cannot  modify  tag  "%s"  while  writing.   Data  has
       already  been  written to the file, so the specified tag's
       value can not be changed.  This restriction is applied  to
       all tags that affect the format of written data.

       %d: Bad value for "%s".  An invalid value was supplied for
       the named tag.


SEE ALSO

       libtiff(3T), TIFFOpen(3T), TIFFGetField(3T), TIFFSetDirec­
       tory(3T), TIFFWriteDirectory(3T), TIFFReadDirectory(3T)


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