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, uint32 width,
uint32 height, uint32 *raster, int
stopOnError)
int TIFFReadRGBAImageOriented(TIFF *tif, uint32
width, uint32 height, uint32
*raster, int orientation, int
stopOnError)
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).
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.
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 ALSO¶
TIFFOpen(3TIFF),
TIFFRGBAImage(3TIFF),
TIFFReadRGBAStrip(3TIFF),
TIFFReadRGBATile(3TIFF),
libtiff(3TIFF)
Libtiff library home page:
http://www.remotesensing.org/libtiff/