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+ TIFFReadRGBAImage, TIFFReadRGBAImageOriented − read +and decode an image into a fixed-format raster + |
+
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+ #include <tiffio.h> + +#define TIFFGetR(abgr) ((abgr) & 0xff) int TIFFReadRGBAImage(TIFF *tif,
+u_long width, u_long height,
+u_long *raster, int
+stopOnError) |
+
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+ TIFFReadRGBAImage reads a strip- or tile-based +image into memory, storing the result in the user supplied +raster. The raster is assumed to be an array of +width times height 32-bit entries, where +width must be less than or equal to the width of the +image (height may be any non-zero size). If the +raster dimensions are smaller than the image, the image data +is cropped to the raster bounds. If the raster height is +greater than that of the image, then the image data are +placed in the lower part of the raster. (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.) + +TIFFReadRGBAImageOriented works like +TIFFReadRGBAImage with except of that user can +specify the raster origin position with the +orientation parameter. Four orientations +supported: + |
+
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+ ORIENTATION_TOPLEFT |
+
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+ origin in top-left corner, + |
+
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+ ORIENTATION_TOPRIGHT |
+
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+ origin in top-right corner, + |
+
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+ ORIENTATION_BOTLEFT |
+
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+ origin in bottom-left corner and + |
+
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+ ORIENTATION_BOTRIGHT |
+
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+ origin in bottom-right corner. + |
+
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+ If you choose ORIENTATION_BOTLEFT result will be +the same as returned by the TIFFReadRGBAImage. + +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). + +TIFFReadRGBAImage converts non-8-bit images by +scaling sample values. Palette, grayscale, bilevel, +CMYK , and YCbCr images are converted to +RGB transparently. Raster pixels are returned +uncorrected by any colorimetry information present in the +directory. + +The paramater stopOnError specifies how to act if +an error is encountered while reading the image. If +stopOnError is non-zero, then an error will terminate +the operation; otherwise TIFFReadRGBAImage will +continue processing data until all the possible data in the +image have been requested. + |
+
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+ In C++ the stopOnError parameter defaults to +0. + +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). + +Palettte image colormaps that appear to be incorrectly +written as 8-bit values are automatically scaled to +16-bits. + +TIFFReadRGBAImage is just a wrapper around the +more general TIFFRGBAImage(3TIFF) facilities. + |
+
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+ 1 is returned if the image was successfully read and +converted. Otherwise, 0 is returned if an error was +encountered and stopOnError is zero. + |
+
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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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+ TIFFOpen(3TIFF), TIFFRGBAImage(3TIFF), +TIFFReadRGBAStrip(3TIFF), +TIFFReadRGBATile(3TIFF), libtiff(3TIFF) + +Libtiff library home page: +http://www.remotesensing.org/libtiff/ + |
+