TIFFReadRGBAImage(3TIFF) Image Format Library C++ Reference Manual
NAME
TIFFReadRGBAImage, TIFFReadRGBAImageOriented - read and decode an image
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 TIFFReadRGBAImage(TIFF *tif, u_long width, u_long height
int TIFFReadRGBAImageOriented(TIFF *tif, u_long width, u_long height
DESCRIPTION
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:
ORIENTATION_TOPLEFT
origin in top-left corner,
ORIENTATION_TOPRIGHT
origin in top-right corner,
ORIENTATION_BOTLEFT
origin in bottom-left corner and
ORIENTATION_BOTRIGHT
origin in bottom-right corner.
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).
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TIFFReadRGBAImage(3TIFF) Image Format Library C++ Reference Manual
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.
NOTES
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.
RETURN VALUES
1 is returned if the image was successfully read and converted.
Otherwise, 0 is returned if an error was encountered and stopOnError is
zero.
DIAGNOSTICS
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.
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TIFFReadRGBAImage(3TIFF) Image Format Library C++ Reference Manual
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 ALSOTIFFOpen(3TIFF), TIFFRGBAImage(3TIFF), TIFFReadRGBAStrip(3TIFF),
TIFFReadRGBATile(3TIFF), libtiff(3TIFF)
Libtiff library home page: http://www.remotesensing.org/libtiff/
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