<meta content="groff -Thtml, see www.gnu.org" name="generator">

<meta content="text/css" name="Content-Style">

<title>TIFFReadRGBAStrip</title>

TIFFReadRGBAStrip

NAME

SYNOPSIS

DESCRIPTION

NOTES

RETURN VALUES

DIAGNOSTICS

SEE ALSO

NAME

       cols="2" cellspacing="0" cellpadding="0">

TIFFReadRGBAStrip − read and decode an image strip

into a fixed-format raster

SYNOPSIS

       cols="2" cellspacing="0" cellpadding="0">

#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 TIFFReadRGBAStrip(TIFF *tif,

uint32 row, uint32

*raster)

DESCRIPTION

       cols="2" cellspacing="0" cellpadding="0">

TIFFReadRGBAStrip reads a single strip of a

strip-based image into memory, storing the result in the

user supplied RGBA raster. The raster is assumed to

be an array of width times rowsperstrip 32-bit entries,

where width is the width of the image (TIFFTAG_IMAGEWIDTH)

and rowsperstrip is the maximum lines in a strip

(TIFFTAG_ROWSPERSTRIP).

The row value should be the row of the first row

in the strip (strip * rowsperstrip, zero based).

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 of the

strip. That is bottom to top organization. When reading a

partial last strip in the file the last line of the image

will begin at the beginning of the buffer.

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).

See the TIFFRGBAImage(3TIFF) page for more details

on how various image types are converted to RGBA values.

NOTES

       cols="2" cellspacing="0" cellpadding="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).

Palette image colormaps that appear to be incorrectly

written as 8-bit values are automatically scaled to

16-bits.

TIFFReadRGBAStrip is just a wrapper around the

more general TIFFRGBAImage(3TIFF) facilities.

It’s main advantage over the similar

TIFFReadRGBAImage() function is that for large images

a single buffer capable of holding the whole image

doesn’t need to be allocated, only enough for one

strip. The TIFFReadRGBATile() function does a similar

operation for tiled images.

RETURN VALUES

       cols="2" cellspacing="0" cellpadding="0">

1 is returned if the image was successfully read and

converted. Otherwise, 0 is returned if an error was

encountered.

DIAGNOSTICS

       cols="2" cellspacing="0" cellpadding="0">

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

       cols="2" cellspacing="0" cellpadding="0">

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

TIFFReadRGBAImage(3TIFF),

TIFFReadRGBATile(3TIFF), libtiff(3TIFF)

Libtiff library home page:

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