TIFFReadRGBAImage(3t)
TIFFReadRGBAImage(3TIFFMISC. REFERENCE MANUAL PAGETIFFReadRGBAImage(3TIFF)
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 ras-
ter is assume to be organized such that the pixel at loca-
tion (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 sam-
ples. The macros TIFFGetR, TIFFGetG, TIFFGetB, and TIFFGetA
should be used to access individual samples. Images without
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TIFFReadRGBAImage(3TIFFMISC. REFERENCE MANUAL PAGETIFFReadRGBAImage(3TIFF)
Associated Alpha matting information have a constant Alpha
of 1.0 (255).
TIFFReadRGBAImage converts non-8-bit images by scaling sam-
ple 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; other-
wise 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. SamplesPer-
Pixel minus ExtraSamples).
Palettte image colormaps that appear to be incorrectly writ-
ten 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 con-
verted. Otherwise, 0 is returned if an error was encoun-
tered and stopOnError is zero.
DIAGNOSTICS
All error messages are directed to the TIFFError(3TIFF) rou-
tine.
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 Sam-
plesPerPixel 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.
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TIFFReadRGBAImage(3TIFFMISC. REFERENCE MANUAL PAGETIFFReadRGBAImage(3TIFF)
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 insuf-
ficient 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 PhotometricInterpre-
tation) 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
libtiff(3TIFF), TIFFOpen(3TIFF), TIFFRGBAImage(3TIFF),
TIFFReadRGBAStrip(3TIFF), TIFFReadRGBATile(3TIFF)
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