TIFFReadRGBAStrip(3t)

TIFFReadRGBAStrip(3TMISC. REFERENCE MANUAL PAGETIFFReadRGBAStrip(3T)

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 supplied
     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 (TIFFTAG_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 ras-
     ter 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  sam-
     ples.  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(3T) page for more details on how vari-
     ous image types are converted to RGBA values.

NOTES

     Samples must be either 1, 2, 4, 8, or 16 bits.  Colorimetric
     samples/pixel  must  be either 1, 3, or 4 (i.e.  SamplesPer-
     Pixel minus ExtraSamples).

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

     TIFFReadRGBAStrip is just a wrapper around the more  general
     TIFFRGBAImage(3T)  facilities.  It's main advantage over the

                 Last change: December 10, 1998                 1

TIFFReadRGBAStrip(3TMISC. REFERENCE MANUAL PAGETIFFReadRGBAStrip(3T)

     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  con-
     verted.   Otherwise,  0  is returned if an error was encoun-
     tered.

DIAGNOSTICS

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

     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 Sam-
     plesPerPixel 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 insuf-
     ficient  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 memory to
     allocate an i/o buffer.

     Can not handle format.  The image has a format  (combination
     of  BitsPerSample, SamplesPerPixel, and PhotometricInterpre-
     tation) that TIFFReadRGBAImage can not handle.

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TIFFReadRGBAStrip(3TMISC. REFERENCE MANUAL PAGETIFFReadRGBAStrip(3T)

     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  insufficient
     memory to allocate a table used to map data to 8-bit RGB.

BUGS

     Orientations other than bottom-left,  or  top-left  are  not
     handled correctly.

SEE ALSO

     libtiff(3T),        TIFFOpen(3T),         TIFFRGBAImage(3T),
     TIFFReadRGBAImage(3T), TIFFReadRGBATile(3T)

                 Last change: December 10, 1998                 3