Table of Contents

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 )DescriptionTIFFReadRGBAStrip
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 raster 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 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
various image types are converted to RGBA values. 
NotesSamples 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. 
TIFFReadRGBAStrip is just a wrapper around the more general 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 Values1 is returned
if the image was successfully read and converted. Otherwise, 0 is returned
if an error was encountered. DiagnosticsAll error messages are directed
to the TIFFError(3) 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. 
No space for Palette mapping table. There was insufficient memory
to allocate a table used to map data to 8-bit RGB. 
See Alsolibtiff(3), TIFFOpen(3),
TIFFRGBAImage(3), TIFFReadRGBAImage(3), TIFFReadRGBATile(3)