TIFFReadRGBAStrip
TIFFReadRGBAStrip(3T) TIFFReadRGBAStrip(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 mem-
ory, 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_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 organiza-
tion. 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(3T) 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 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 general TIFFRGBAIm-
age(3T) facilities. It's main advantage over the similar TIFFReadRG-
BAImage() 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. Other-
wise, 0 is returned if an error was encountered.
DIAGNOSTICS
All error messages are directed to the TIFFError(3T) 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 miss-
ing 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 mem-
ory 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 BitsPer-
Sample, SamplesPerPixel, and PhotometricInterpretation) that TIFFRead-
RGBAImage can not handle.
No space for B&W mapping table. There was insufficient memory to allo-
cate 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 cor-
rectly.
SEE ALSO
libtiff(3T), TIFFOpen(3T), TIFFRGBAImage(3T), TIFFReadRGBAImage(3T),
TIFFReadRGBATile(3T)
December 10, 1998 TIFFReadRGBAStrip(3T)
