functions in yeti_tiff.i -

             tiff_check(filename)  
 
    Check whether or not FILENAME is an existing TIFF file, returned value  
    is: 1 if FILENAME is a readable big endian TIFF file,  
        2 if FILENAME is a readable little endian TIFF file,  
        0 otherwise (FILENAME unreadable or not a TIFF file).  
    Note  that the  check is  intended to  be fast,  it is  not completely  
    reliable since only the 2 first bytes of FILENAME are used.  
    

             tiff_debug(value)  
 
    Set  debug flag  for TIFF  operations and  returns the  previous debug  
    value.   If  VALUE is  true,  TIFF  warning  messages get  printed  to  
    standard error; otherwise these messages are never printed.  

             tiff_open(filename)  
 
      -or- tiff_open(filename, filemode)  
    Open TIFF file FILENAME with mode FILEMODE (default "r", i.e. reading)  
    and return an opaque handle that  can be used to manage the TIFF file.  
    The returned  handle can also be  used like a structure  to query TIFF  
    field or pseudo-tag value, e.g.:  
    
       obj = tiff_open(filename);  
       width = obj.imagewidth;    // width of image  
       height = obj.imagelength;  // height of image  
    
    If TIFF field or pseudo-tag MEMBER is undefined, then OBJ.MEMBER gives  
    a nil value;  but if the field or pseudo-tag  MEMBER is unsupported or  
    does  not  exist in  TIFF  specification,  an  error is  raised.   The  
    identifiers of TIFF fields or  pseudo-tags can be guessed from the tag  
    macros   in  "tiff.h"   header   file  from   libtiff  library   (e.g.  
    TIFFTAG_IMAGEDESCRIPTION  becomes "imagedescription"), this  file also  
    gives some description about the tag values.  Additional tags are:  
    
       obj.filename    // full path of file (scalar string)  
       obj.filemode    // file mode (scalar string)  
    
    The value of the TIFF tags can also be obtained by indexing the TIFF  
    object with the tag name, for instance:  
    
       width = obj("imagewidth");    // width of image  
       path = obj("filename");       // path of image file  
    
    

             tiff_read(filename)  
 
    Return  a  grayscale  or  RGBA  image from  TIFF  file  FILENAME  (see  
    tiff_read_image) or  an array of pixel  values if keyword  RAW is true  
    (see tiff_read_pixels).  Keyword INDEX may be used to specify the TIFF  
    directory number of the image to read (default INDEX=1).  
    

             tiff_read_directory(obj)  
 
    Read the next directory in the  specified file and make it the current  
    directory.  Applications only need to call tiff_read_directory to read  
    multiple subfiles  in a single TIFF  file -- the first  directory in a  
    file  is automatically  read when  tiff_open is  called.  If  the next  
    directory was  successfully read, 1 is returned.   Otherwise, if there  
    are no more directories to be read, 0 is returned.  
    

             tiff_read_image(obj)  
 
      -or- tiff_read_image(obj, stop_on_error)  
    Returns    image    data     in    current    "TIFF-directory"    (see  
    tiff_read_directory) of TIFF handle OBJ.  The result is a WIDTH×HEIGHT  
    array for  a grayscale  image and a  4×WIDTH×HEIGHT array for  a color  
    image (the first  dimension correspond to: red, green,  blue and alpha  
    channels).  If optional argument STOP_ON_ERROR is true (it is false by  
    default),  then  any  error   while  reading  the  image  get  raised;  
    otherwise,  a simple warning  is printed  out (note:  in any  case, an  
    error is raised if there is not enough memory to store the image or if  
    the image format is unsupported).  
    

             tiff_read_pixels(obj)  
 
    Returns  pixel  values  of  image  in  current  "TIFF-directory"  (see  
    tiff_read_directory) of TIFF handle OBJ.  The result is a WIDTH×HEIGHT  
    array   for    a   grayscale   or   a   colormapped    image   and   a  
    SAMPLESPERPIXEL×WIDTH×HEIGHT array for an RGB image.