#define TIFFGetR(abgr) ((abgr) & 0xff)
#define TIFFGetG(abgr) (((abgr) >> 8) & 0xff)
#define TIFFGetB(abgr) (((abgr) >> 16) & 0xff)
#define TIFFGetA(abgr) (((abgr) >> 24) & 0xff)
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).
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(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 strip. The TIFFReadRGBATile() function does a similar operation for tiled images.
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.
Libtiff library home page: http://www.remotesensing.org/libtiff/