TIFFREADRGBATILE(3tiff) LibTIFF TIFFREADRGBATILE(3tiff)
NAME
TIFFReadRGBATile - read and decode an image tile into a fixed-format
raster
SYNOPSIS
#include <tiffio.h>
int TIFFReadRGBATile(TIFF *tif, uint32_t x, uint32_t y, uint32_t
*raster)
int TIFFReadRGBATileExt(TIFF *tif, uint32_t col, uint32_t row, uint32_t
*raster, int stop_on_error)
DESCRIPTION
TIFFReadRGBATile() reads a single tile of a tile-based image into mem-
ory, storing the result in the user supplied RGBA raster. The raster
is assumed to be an array of TileWidth × TileLength 32-bit entries,
where TileWidth is the width of a tile (TIFFTAG_TILEWIDTH) and Tile-
Length is the height of a tile (TIFFTAG_TILELENGTH).
TIFFReadRGBATileExt() provides the parameter stop_on_error. Its behav-
iour is described at TIFFReadRGBAImage.
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 organiza-
tion. 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 ac-
cess individual samples. Images without Associated Alpha matting infor-
mation have a constant Alpha of 1.0 (255).
See the TIFFRGBAImage 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 sam-
ples/pixel must be either 1, 3, or 4 (i.e. SamplesPerPixel - ExtraSam-
ples).
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 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. Other-
wise, 0 is returned if an error was encountered.
DIAGNOSTICS
All error messages are directed to the TIFFErrorExtR() 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 sam-
ples 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, SamplesPer-
Pixel, 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.
"No space for Palette mapping table":
There was insufficient memory to allocate a table used to map data
to 8-bit RGB.
SEE ALSO
TIFFOpen (3tiff), TIFFRGBAImage (3tiff), TIFFReadRGBAImage (3tiff),
TIFFReadRGBAStrip (3tiff), libtiff (3tiff)
AUTHOR
LibTIFF contributors
COPYRIGHT
1988-2023, LibTIFF contributors
4.5 Nov 23, 2023 TIFFREADRGBATILE(3tiff)
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