Image data classes

Detailed Description

Image data unit containers and tools.

Raster, VecRaster, PtrRaster

The central class for image data representation is Raster. It is the in-memory representation of the n-D arrays of FITS. A raster is defined by:

• A dimension (number of axes) as template parameter N;
• A value type as template parameter T;
• A shape, of type Position<N>, which is a sequence of indices, and can be viewed as an alias of std::array<long, N> or std::vector<long>;
• Some data, i.e. the pixel values, stored contiguously, for example in a std::vector.

Two specialization are provided for convenience:

• PtrRaster merely stores a pointer to the data array;
• VecRaster owns itself the data as an std::vector.

Functions which return a Raster generally return a VecRaster (e.g. ImageRaster::read()). All methods which take a Raster as input accept whatever flavor of it.

For convenience, make_raster() functions enable raster creation without template parameters.

Position, Region, PositionIterator

In addition, a few helper classes are defined:

• Position, which was already mentioned, represents the shape of the raster, as well as the pixel positions;
• Region is a pair of Positions used for example to represent the raster domain or to read and write image regions;
• PositionIterator is used to screen a region – it is instanciated by begin() and end(), which in turn enables range loops over regions, e.g. for (const auto& p : image.domain()).

Typedefs
template<typename T , long N = 2>
using	PtrRaster = Raster< T, N, DataContainerHolder< T, T * > >
	Raster which points to some external data (THolder = T*).
template<typename T , long N = 2>
using	VecRaster = Raster< T, N, DataContainerHolder< T, std::vector< T > > >
	Raster which owns a data vector (THolder = std::vector<T>).

Classes
class	Position< N >
	n-dimensional pixel position or image shape, i.e. set of integer coordinates. More...
class	PositionIterator< N >
	A helper class to screen a Region. More...
class	Raster< T, N, THolder >
	Data of a n-dimensional image (2D by default). More...
struct	Region< N >
	A n-D rectangle region, defined by its front and back positions (both inclusive), or front position and shape. More...

Macros
#define	ELEFITS_FOREACH_RASTER_TYPE(MACRO)
	Loop over supported raster types. More...