tiffreadrgbastrip(3)
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, tstrip_t strip, 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 rowsper
strip is the maximum lines in a strip (TIFFTAG_ROWSPER
STRIP).
The strip value should be the strip number (strip zero is
the first) as returned by the TIFFComputeStrip function,
but always for sample 0.
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 par
tial 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(3) page for more details on how var
ious image types are converted to RGBA values.
NOTES
Samples must be either 1, 2, 4, 8, or 16 bits. Colorimet
ric samples/pixel must be either 1, 3, or 4 (i.e. Sam_
plesPerPixel 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(3) 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
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(3) 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
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 (combina tion of BitsPerSample, SamplesPerPixel, and PhotometricIn_ terpretation) 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.
BUGS
Orientations other than bottom-left, or top-left are not
handled correctly.
SEE ALSO
- libtiff(3), TIFFOpen(3), TIFFRGBAImage(3), TIFFReadRGBAIm_
age(3), TIFFReadRGBATile(3)