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TIFFReadRGBAStrip − read and decode an image strip into a fixed-format raster |
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#include <tiffio.h> |
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#define TIFFGetR(abgr) |
((abgr) & 0xff) |
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#define TIFFGetG(abgr) |
(((abgr) >> 8) & 0xff) |
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#define TIFFGetB(abgr) |
(((abgr) >> 16) & 0xff) |
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#define TIFFGetA(abgr) |
(((abgr) >> 24) & 0xff) |
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int TIFFReadRGBAStrip(TIFF *tif, uint32 row, uint32 *raster) |
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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 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(3TIFF) page for more details on how various image types are converted to RGBA values. |
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Samples 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(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. |
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1 is returned if the image was successfully read and converted. Otherwise, 0 is returned if an error was encountered. |
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All error messages are directed to the TIFFError(3TIFF) 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. |
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libtiff(3TIFF), TIFFOpen(3TIFF), TIFFRGBAImage(3TIFF), TIFFReadRGBAImage(3TIFF), TIFFReadRGBATile(3TIFF) |