Raster< T, N, THolder > Class Template Reference

#include <Raster.h>

Detailed Description

template<typename T, long N, typename THolder>
class Euclid::Fits::Raster< T, N, THolder >

Data of a n-dimensional image (2D by default).

Template Parameters

T	The value type, which can be const-qualified for read-only rasters
N	The dimension, which can be ≥ 0 for fixed dimension, or -1 for variable dimension
THolder	The underlying data container type

A raster is a contiguous container for the pixel data of an image. It features access and view services.

There are two ways of defining the dimension of a Raster:

• When the dimension is knwon at compile-time (safer), by giving the dimension parameter a positive or null value;
• When the dimension is known at run-time only (more flexible), by assigning N = -1.

In the former case, index and size computations are optimized, and the dimension is enforced. For example, it is not possible to read a 3D image HDU as a 2D Raster – which is nice, because an exception will be raised early! In contrast, it is possible to read a 2D image HDU as a 3D Raster of third axis lenght =1.

In the latter case, the dimension may vary or be deduced from the file, which is also nice sometimes but puts more responsibility on the shoulders of the user code, as it should check that the actual dimension is acceptable.

Raster meets the ContiguousContainer requirements, by extending DataContainer (e.g. is iterable). Raster ensures constant-time access to elements, whatever the dimension of the data, through subscipt operator Raster::operator[](). Bound checking and backward indexing (index <0) are enabled in Raster::at().

Raster also implements some arithmetic operators by extending VectorArithmeticMixin. For example, two rasters can be added, or a raster can be multiplied by a scalar.

The raster data can be viewed region-wise as a PtrRaster, provided that the region is contiguous in memory. Reading and writing non contiguous region is possible: see ImageRaster.

Template specialization PtrRaster

Raster which points to some external data (THolder = T*). More...

Template specialization VecRaster

Raster which owns a data vector (THolder = std::vector<T>). More...

Satisfies `ContiguousContainer` requirements

A contiguous container is a standard container whose elements are stored contiguously in memory.

Satisfies `VectorArithmetic` requirements

Implements vector space arithmetic operators (uppercase letters are for vectors, lowercase letters are for scalars):

• Vector-additive: V += U, W = V + U, V += U, W = V - U;
• Scalar-additive: V += a, V = U + a, V = a + U, V -= a, V = U + a, V = a - U;
• Scalar-multiplicative: V *= a, V = U * a, V = a * U, V /= a, V = U / a;
• Incrementation if enabled (for integral value types by default): V++, ++V, V–, –V.

See also

Position for details on the fixed- and variable-dimension cases.

makeRaster() for creation shortcuts.

Example

Position<2> shape {2, 3};
 
// Read/write PtrRaster
float data[] = {1, 2, 3, 4, 5, 6};
PtrRaster<float> ptrRaster(shape, data);
 
// Read-only PtrRaster
const float cData[] = {1, 2, 3, 4, 5, 6};
PtrRaster<const float> cPtrRaster(shape, cData);
 
// Read/write VecRaster
std::vector<float> vec(&data[0], &data[6]);
VecRaster<float> vecRaster(shape, std::move(vec));
 
// Read-only VecRaster
std::vector<const float> cVec(&data[0], &data[6]);
VecRaster<const float> cVecRaster(shape, std::move(cVec));

Note

Why "raster" and not simply image or array? Mostly for disambiguation purpose: "image" refers to the extension type, while "array" has already several meanings in C/C++. NdArray would have been an option, but every related class should have been prefixed with Nd for homogeneity: NdPosition, NdRegion, VecNdArray... From the cathodic television era, raster also historically carries the concept of contiguous pixels, is very common in the field of Earth observation, and also belongs to the Java library. All in all, Raster seems to be a fair compromise.

Examples

EleFitsTutorial.cpp.

Public Types
using	Value = T
	The pixel value type.
Public Types inherited from DataContainer< T, THolder, Raster< T, N, THolder > >
using	Container = typename Holder::Container
	The concrete container type.
using	Holder = THolder
	The concrete data holder type.
Public Types inherited from ContiguousContainerMixin< T, TDerived >
using	const_iterator = const T *
	The constant value iterator.
using	const_reference = const T &
	The constant value reference.
using	difference_type = std::ptrdiff_t
	The iterator difference type.
using	iterator = T *
	The value iterator.
using	reference = T &
	The value reference.
using	size_type = std::size_t
	The underlying container size type.
using	value_type = T
	The value type.

Static Public Attributes
static constexpr long	Dim = N
	The dimension template parameter. More...

Public Member Functions
Construction
	Raster (Position< N > shape)
	Constructor. More...
template<typename U >
	Raster (Position< N > shape, U *data)
	Constructor. More...
template<typename... Ts>
	Raster (Position< N > shape, Ts &&... args)
	Constructor. More...
Properties
const Position< N > &	shape () const
	Get the raster shape.
Region< N >	domain () const
	Get the raster domain. More...
long	dimension () const
	Get the actual dimension. More...
template<long I>
long	length () const
	Get the length along given axis.
Element access
long	index (const Position< N > &pos) const
	Compute the raw index of a given position.
const T &	operator[] (const Position< N > &pos) const
	Access the pixel value at given position.
T &	operator[] (const Position< N > &pos)
	Access the pixel value at given position.
const T &	at (const Position< N > &pos) const
	Access the pixel value at given position. More...
T &	at (const Position< N > &pos)
	Access the pixel value at given position.
Views
template<long M = 2>
bool	isContiguous (const Region< N > &region) const
	Check whether a region is made of contiguous values in memory. More...
template<long M = 2>
const PtrRaster< const T, M >	slice (const Region< N > &region) const
	Create a slice from a given region. More...
template<long M = 2>
PtrRaster< T, M >	slice (const Region< N > &region)
	Create a slice from a given region.
const PtrRaster< const T, N >	section (long front, long back) const
	Create a section between given indices. More...
PtrRaster< T, N >	section (long front, long back)
	Create a section between given indices.
const PtrRaster< const T, N==-1 ? -1 :N - 1 >	section (long index) const
	Create a section at given.
PtrRaster< T, N==-1 ? -1 :N - 1 >	section (long index)
	Create a section at given.
Public Member Functions inherited from DataContainer< T, THolder, Raster< T, N, THolder > >
	DataContainer (TSize s=0, std::remove_const_t< T > *d=nullptr)
	Construct from a size and non-constant data.
	DataContainer (TSize s, const T *d)
	Construct from a size and constant data.
	DataContainer (TIterator begin, TIterator end)
	Iterator-based constructor.
	DataContainer (std::initializer_list< T > values)
	Value list constructor.
	DataContainer (TArg0 arg0, TArgs &&... args)
	Forwarding constructor.
T *	data ()
const std::decay_t< Container > &	container () const
	Access the container in read-only mode.
Container &	moveTo (Container &destination)
	Move the container. More...
Public Member Functions inherited from ContiguousContainerMixin< T, TDerived >
bool	empty () const
	Check whether the container is empty. More...
const T &	operator[] (size_type index) const
	Access the element with given index.
T &	operator[] (size_type index)
	Access the element with given index.
const_iterator	begin () const
	Iterator to the first element.
iterator	begin ()
	Iterator to the first element.
const_iterator	cbegin ()
	Iterator to the first element.
const_iterator	end () const
	Iterator to one past the last element.
iterator	end ()
	Iterator to one past the last element.
const_iterator	cend ()
	Iterator to one past the last element.
virtual bool	operator== (const TDerived &rhs) const
	Check equality.
bool	operator!= (const TDerived &rhs) const
	Check inequality.
Public Member Functions inherited from VectorArithmeticMixin< T, TDerived, Incrementable >
TDerived &	operator+= (const TDerived &rhs)
	V += U and W = V + U.
TDerived &	operator+= (const T &rhs)
	V += a, V = U + a, V = a + U.
TDerived &	operator-= (const TDerived &rhs)
	V -= U and W = V - U.
TDerived &	operator-= (const T &rhs)
	V -= a, V = U - a, V = a - U.
TDerived &	operator*= (const T &rhs)
	V *= a, V = U * a, V = a * U.
TDerived &	operator/= (const T &rhs)
	V /= a, V = U / a.
template<typename TFunc , typename... TContainers>
TDerived &	generate (TFunc &&func, const TContainers &... args)
	Generate values from a function with optional input containers. More...
template<typename TFunc , typename... TContainers>
TDerived &	apply (TFunc &&func, const TContainers &... args)
	Apply a function with optional input containers. More...
TDerived	operator+ () const
	Copy.
TDerived	operator- () const
	Compute the opposite.

Related Functions
(Note that these are not member functions.)
template<typename TRaster >
constexpr long	bitpix (const TRaster &)
	Get the BITPIX value of a given raster.
template<typename T , typename... Longs>
PtrRaster< T, sizeof...(Longs)>	makeRaster (T *data, Longs... shape)
template<typename TContainer , typename... Longs>
Raster< typename TContainer::value_type, sizeof...(Longs), DataContainerHolder< typename TContainer::value_type, TContainer > >	makeRaster (TContainer &&data, Longs... shape)
	Shortcut to create a raster from a shape and data without specifying the template parameters. More...
Related Functions inherited from ContiguousContainerMixin< T, TDerived >
template<typename T , typename TDerived >
std::ostream &	operator<< (std::ostream &os, const ContiguousContainerMixin< T, TDerived > &container)
	Insert a ContiguousContainerMixin into an output stream.

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The documentation for this class was generated from the following file:

• EleFitsData/EleFitsData/Raster.h