# TIFFReadRGBAStrip

NAME
SYNOPSIS
DESCRIPTION
NOTES
RETURN VALUES
DIAGNOSTICS
SEE ALSO

## NAME

TIFFReadRGBAStrip − read and decode an image strip 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 TIFFReadRGBAStrip(TIFF *tif, uint32_t row, uint32_t *raster)

## DESCRIPTION

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

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

1 is returned if the image was successfully read and converted. Otherwise, 0 is returned if an error was encountered.

## 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), TIFFReadRGBAImage(3TIFF), TIFFReadRGBATile(3TIFF), libtiff(3TIFF)

Libtiff library home page: http://www.simplesystems.org/libtiff/