TIFFReadRGBAImage(3TIFF) TIFFReadRGBAImage(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, uint32_t width, uint32_t height,
uint32_t *raster, int stopOnError)
int TIFFReadRGBAImageOriented(TIFF *tif, uint32_t width, uint32_t
height, uint32_t *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 parameter 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.simplesystems.org/libtiff/

libtiff October 13, 2006 TIFFReadRGBAImage(3TIFF)