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TIFFReadRGBAImage

NAME

SYNOPSIS

DESCRIPTION

NOTES

RETURN VALUES

DIAGNOSTICS

SEE ALSO

NAME

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TIFFReadRGBAImage, TIFFReadRGBAImageOriented − read

and decode an image into a fixed-format raster

SYNOPSIS

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#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

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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,

<small>CMYK</small> , and YCbCr images are converted to

<small>RGB</small> 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

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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.

RETURN VALUES

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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.

DIAGNOSTICS

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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 <small>RGB.</small>

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 <small>RGB.</small>

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 <small>RGB.</small>

No space for Palette mapping table. There was

insufficient memory to allocate a table used to map data to

8-bit <small>RGB.</small>

SEE ALSO

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TIFFOpen(3TIFF), TIFFRGBAImage(3TIFF),

TIFFReadRGBAStrip(3TIFF),

TIFFReadRGBATile(3TIFF), libtiff(3TIFF)

Libtiff library home page:

http://www.remotesensing.org/libtiff/