TIFFReadRGBAStrip(3TIFF)               TIFFReadRGBAStrip(3TIFF)





NAME
       TIFFReadRGBAStrip  - read and decode an image strip into
       a fixed-format raster

SYNOPSIS
       #include <tiffio.h>

       #define TIFFGetR(abgr) ((abgr) & 0xff)
       #define TIFFGetG(abgr) (((abgr) >> 8) & 0xff)
       #define TIFFGetB(abgr) (((abgr) >> 16) & 0xff)
       #define TIFFGetA(abgr) (((abgr) >> 24) & 0xff)

       int  TIFFReadRGBAStrip(TIFF  *tif,  uint32  row,  uint32
       *raster)

DESCRIPTION
       TIFFReadRGBAStrip  reads a single strip of a strip-based
       image into memory, storing the result in the  user  sup-
       plied RGBA raster.  The raster is assumed to be an array
       of width times rowsperstrip 32-bit entries, where  width
       is  the  width  of  the  image  (TIFFTAG_IMAGEWIDTH) and
       rowsperstrip is the maximum  lines  in  a  strip  (TIFF-
       TAG_ROWSPERSTRIP).


       The  row value should be the row of the first row in the
       strip (strip * rowsperstrip, zero based).


       Note that the raster is assume to be organized such that
       the  pixel  at location (x,y) is raster[y*width+x]; with
       the raster origin in the lower-left hand corner  of  the
       strip. That is bottom to top organization.  When reading
       a partial last strip in the file the last  line  of  the
       image will begin at the beginning of the buffer.


       Raster  pixels  are 8-bit packed red, green, blue, alpha
       samples. The macros TIFFGetR,  TIFFGetG,  TIFFGetB,  and
       TIFFGetA  should  be  used to access individual samples.
       Images without Associated Alpha matting information have
       a constant Alpha of 1.0 (255).

       See  the  TIFFRGBAImage(3TIFF)  page for more details on
       how various image types are converted to RGBA values.

NOTES
       Samples must be either 1, 2, 4, 8, or 16  bits.  Colori-
       metric  samples/pixel  must  be  either 1, 3, or 4 (i.e.
       SamplesPerPixel minus ExtraSamples).

       Palette image colormaps that appear  to  be  incorrectly
       written  as  8-bit  values  are  automatically scaled to
       16-bits.

       TIFFReadRGBAStrip is just a wrapper around the more gen-
       eral  TIFFRGBAImage(3TIFF) facilities.  It's main advan-
       tage over the similar  TIFFReadRGBAImage()  function  is
       that for large images a single buffer capable of holding
       the whole image  doesn't  need  to  be  allocated,  only
       enough  for  one strip.  The TIFFReadRGBATile() function
       does a similar operation for tiled images.

RETURN VALUES
       1 is returned if the image  was  successfully  read  and
       converted.   Otherwise,  0  is  returned if an error was
       encountered.

DIAGNOSTICS
       All error messages are directed to the  TIFFError(3TIFF)
       routine.

       Sorry,  can  not  handle %d-bit pictures.  The image had
       BitsPerSample other than 1, 2, 4, 8, or 16.

       Sorry, can not handle %d-channel images.  The image  had
       SamplesPerPixel other than 1, 3, or 4.

       Missing  needed  "PhotometricInterpretation"  tag.   The
       image did not have a tag that describes how  to  display
       the data.

       No  "PhotometricInterpretation"  tag, assuming RGB.  The
       image was missing a tag that describes  how  to  display
       it,  but  because  it  has  3  or 4 samples/pixel, it is
       assumed to be RGB.

       No  "PhotometricInterpretation"  tag,  assuming  min-is-
       black. The image was missing a tag that describes how to
       display it, but because it has  1  sample/pixel,  it  is
       assumed to be a grayscale or bilevel image.

       No  space  for  photometric conversion table.  There was
       insufficient memory for a table used  to  convert  image
       samples to 8-bit RGB.

       Missing  required  "Colormap"  tag.  A Palette image did
       not have a required Colormap tag.

       No space for tile buffer.  There was insufficient memory
       to allocate an i/o buffer.

       No  space for strip buffer.  There was insufficient mem-
       ory to allocate an i/o buffer.

       Can not handle format.  The image has a format (combina-
       tion   of  BitsPerSample,  SamplesPerPixel,  and  Photo-
       metricInterpretation)  that  TIFFReadRGBAImage  can  not
       handle.

       No  space for B&W mapping table.  There was insufficient
       memory to allocate a table used to map grayscale data to
       RGB.

       No  space for Palette mapping table.  There was insuffi-
       cient memory to allocate a table used  to  map  data  to
       8-bit RGB.

SEE ALSO
       TIFFOpen(3TIFF),  TIFFRGBAImage(3TIFF),  TIFFReadRGBAIm-
       age(3TIFF), TIFFReadRGBATile(3TIFF), libtiff(3TIFF)

       Libtiff  library   home   page:   http://www.remotesens-
       ing.org/libtiff/




libtiff                December 10, 199TIFFReadRGBAStrip(3TIFF)
