◆ readRegion()

VecRaster< T, M > readRegion ( const Region< N > & region ) const

Read a region as a new VecRaster.

Template Parameters

T	The desired raster type
M	The desired raster dimension, which can be smaller than the data dimension in file
N	The region dimension, which corresponds to the data dimension in file

Parameters

region	The in-file region
regions	The in-file and in-memory regions
raster	The destination raster

There are several options to read a region of the data unit:

as a new VecRaster object;
by filling an existing Raster object;
by filling an existing Subraster object. In the last two cases, the in-file and in-memory regions are given as a FileMemRegions object.

For example, to read the HDU region from position (50, 80) to position (100, 120) into an existing raster at position (25, 40), do:

const FileMemRegions<2> regions({25, 40}, {{50, 80}, {100, 120}});

image.readRegionTo(regions, raster);

where image is the ImageRaster and raster is the Raster.

In simpler cases, where the in-file or in-memory front position is 0, factories can be used, e.g. to read into position 0 of the raster:

image.readRegionTo<2>({{50, 80}, {100, 120}}, raster);