Ubuntu Manpage: TIFFReadRGBATile - read and decode an image tile into a fixed-format raster

Provided by: libtiff-dev_4.3.0-6ubuntu0.10_amd64

NAME

       TIFFReadRGBATile - read and decode an image tile 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 TIFFReadRGBATile(TIFF *tif, uint32_t x, uint32_t y, uint32_t *raster)

DESCRIPTION

       TIFFReadRGBATile  reads  a  single tile of a tile-based image into memory, storing the result in the user
       supplied RGBA raster.  The raster is assumed to be an array of width times length 32-bit  entries,  where
       width is the width of a tile (TIFFTAG_TILEWIDTH) and length is the height of a tile (TIFFTAG_TILELENGTH).

       The  x  and  y  values  are the offsets from the top left corner to the top left corner of the tile to be
       read.  They must be an exact multiple of the tile width and length.

       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 tile. That is bottom to
       top organization.  Edge tiles which partly fall off the image will be filled out with appropriate  zeroed
       areas.

       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. Colorimetric 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.

       TIFFReadRGBATile is just a wrapper around the more general TIFFRGBAImage(3TIFF)  facilities.   It's  main
       advantage  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   tile.    The
       TIFFReadRGBAStrip() function does a similar operation for stripped 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 memory to allocate an i/o buffer.

Can not handle format. The image has a format (combination of BitsPerSample, SamplesPerPixel, and
PhotometricInterpretation) 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.