Geometric transformations module #include "diplib/geometry.h"
Geometric image transformations.
Contents
 Interpolation methods
 Reference
Interpolation methods
Many of the functions in this group resample the image using an interpolation method. They all perform
interpolation separately (i.e. along one dimension at the time). These functions have an input argument
called interpolationMethod
, which determines how image data are interpolated. It can be set to one of
the following strings:

"3cubic"
(or""
): Thirdorder cubic spline interpolation (Keys, 1981), using 4 input samples to compute each output sample. This is the default method for most functions. 
"4cubic"
: Fourthorder cubic spline interpolation (Keys, 1981), using 6 input samples to compute each output sample. 
"linear"
: Linear interpolation, using 2 input samples to compute each output sample. 
"nearest"
(or"nn"
): Nearest neighbor interpolation, samples are simply shifted and replicated. 
"inverse nearest"
(or"nn2"
): Nearest neighbor interpolation, but resolves the rounding of x.5 in the opposite direction that"nearest"
does. This is useful when applying the inverse of an earlier transform, to be able to obtain the original geometry back. 
"bspline"
: A thirdorder cardinal Bspline is computed for all samples on an image line, which is sampled anew to obtain the interpolated sample values. All input samples are used to compute all output samples, but only about 10 input samples significantly influence each output value. 
"lanczos8"
: Lanczos interpolation with a = 8, using 16 input samples to compute each output sample. The Lanczos kernel is a sinc function windowed by a larger sinc function, where a is the width of the larger sinc function. The kernel is normalized. 
"lanczos6"
: Lanczos interpolation with a = 6, using 12 input samples to compute each output sample. 
"lanczos4"
: Lanczos interpolation with a = 4, using 8 input samples to compute each output sample. 
"lanczos3"
: Lanczos interpolation with a = 3, using 6 input samples to compute each output sample. 
"lanczos2"
: Lanczos interpolation with a = 2, using 4 input samples to compute each output sample. 
"ft"
: Interpolation through padding and cropping, and/or modifying the phase component of the Fourier transform of the image line. Padding with zeros increases the sampling density, cropping reduces the sampling density, and multiplying the phase component by shifts the image. Equivalent to interpolation with a sinc kernel. All input samples are used to compute all output samples. The boundary condition is ignored, as the Fourier transform imposes a periodic boundary condition.
Not all methods are available for all functions. If so, this is described in the function’s documentation.
For operations on binary images, the interpolation method is ignored, and "nearest"
is always used.
Interpolation methods require a boundary extension of half the number of input samples used to compute each output sample. For Bspline interpolation, a boundary extension of 5 is used. For the nearest neighbor and Fourier interpolation methods, no boundary extension is needed.
Aliases

using dip::
InterpolationFunctionPointer = void(*)(Image, Image::Pixel, FloatArray)  Pointer to an interpolation function. Only use pointers returned by
dip::PrepareResampleAtUnchecked
.
Functions

void dip::
Wrap (dip::Image const& in, dip::Image& out, dip::IntegerArray wrap)  Shifts the input image by an integer number of pixels, wrapping the pixels around.

void dip::
Subsampling (dip::Image const& in, dip::Image& out, dip::UnsignedArray const& sample)  Subsamples the input image.

void dip::
Resampling (dip::Image const& in, dip::Image& out, dip::FloatArray zoom, dip::FloatArray shift = {0.0}, dip::String const& interpolationMethod = "", dip::StringArray const& boundaryCondition = {})  Resamples an image with the given zoom factor and subpixel shift.

void dip::
Shift (dip::Image const& in, dip::Image& out, dip::FloatArray const& shift, dip::String const& interpolationMethod = S::FOURIER, dip::StringArray const& boundaryCondition = {})  Shift an image. Calls
dip::Resampling
withzoom
set to 1, and uses the “ft” method by default. 
void dip::
ShiftFT (dip::Image const& in, dip::Image& out, dip::FloatArray shift = {0.0})  Modulates the input Fourier spectrum to introduce a shift in the spatial domain

void dip::
ResampleAt (dip::Image const& in, dip::Image& out, dip::FloatCoordinateArray const& coordinates, dip::String const& interpolationMethod = S::LINEAR, dip::Image::Pixel const& fill = {0})  Finds the values of the image at subpixel locations
coordinates
by interpolation. 
auto dip::
ResampleAt (dip::Image const& in, dip::FloatArray const& coordinates, dip::String const& interpolationMethod = S::LINEAR, dip::Image::Pixel const& fill = {0}) > dip::Image::Pixel  Identical to the previous function with the same name, but for a single point.

auto dip::
PrepareResampleAtUnchecked (dip::Image const& in, dip::String const& interpolationMethod) > dip::InterpolationFunctionPointer  Prepare for repeated calls to
dip::ResampleAtUnchecked
. Seedip::ResampleAt
. 
auto dip::
ResampleAtUnchecked (dip::Image const& in, dip::FloatArray const& coordinates, dip::InterpolationFunctionPointer function) > dip::Image::Pixel  Similar to
dip::ResampleAt
, but optimized for repeated calls using the same parameters.function
comes fromPrepareResampleAtUnchecked
.fill
is always 0. 
void dip::
ResampleAt (dip::Image const& in, dip::Image const& map, dip::Image& out, dip::String const& interpolationMethod = S::LINEAR, dip::Image::Pixel const& fill = {0})  Resamples an image with subpixel locations specified by a coordinate map.

void dip::
Skew (dip::Image const& in, dip::Image& out, dip::FloatArray const& shearArray, dip::uint axis, dip::String const& interpolationMethod = "", dip::StringArray const& boundaryCondition = {})  Skews (shears) an image

void dip::
Skew (dip::Image const& in, dip::Image& out, dip::dfloat shear, dip::uint skew, dip::uint axis, dip::String const& interpolationMethod = "", dip::String const& boundaryCondition = {})  Skews (shears) an image

void dip::
Rotation (dip::Image const& in, dip::Image& out, dip::dfloat angle, dip::uint dimension1, dip::uint dimension2, dip::String const& interpolationMethod = "", dip::String const& boundaryCondition = S::ADD_ZEROS)  Rotates an image in one orthogonal plane, over the center of the image.

void dip::
Rotation2D (dip::Image const& in, dip::Image& out, dip::dfloat angle, dip::String const& interpolationMethod = "", dip::String const& boundaryCondition = S::ADD_ZEROS)  Rotates a 2D image

void dip::
Rotation3D (dip::Image const& in, dip::Image& out, dip::dfloat angle, dip::uint axis = 2, dip::String const& interpolationMethod = "", dip::String const& boundaryCondition = S::ADD_ZEROS)  Rotates a 3D image in one orthogonal plane

void dip::
Rotation3D (dip::Image const& in, dip::Image& out, dip::dfloat alpha, dip::dfloat beta, dip::dfloat gamma, dip::String const& interpolationMethod = "", dip::String const& boundaryCondition = S::ADD_ZEROS)  Applies an arbitrary 3D rotation to a 3D image

void dip::
RotationMatrix2D (dip::Image& out, dip::dfloat angle)  Creates a 0D (one pixel) 2x2 matrix image containing a 2D rotation matrix.

void dip::
RotationMatrix3D (dip::Image& out, dip::dfloat alpha, dip::dfloat beta, dip::dfloat gamma)  Creates a 0D (one pixel) 3x3 matrix image containing a 3D rotation matrix.

void dip::
RotationMatrix3D (dip::Image& out, dip::FloatArray const& vector, dip::dfloat angle)  Creates a 0D (one pixel) 3x3 matrix image containing a 3D rotation matrix.

void dip::
AffineTransform (dip::Image const& in, dip::Image& out, dip::FloatArray const& matrix, dip::String const& interpolationMethod = S::LINEAR)  Applies an arbitrary affine transformation to the 2D or 3D image.

void dip::
WarpControlPoints (dip::Image const& in, dip::Image& out, dip::FloatCoordinateArray const& inCoordinates, dip::FloatCoordinateArray const& outCoordinates, dip::dfloat lambda = 0, dip::String const& interpolationMethod = S::LINEAR)  Warps an image based on a set of control points using thin plate spline interpolation

void dip::
LogPolarTransform2D (dip::Image const& in, dip::Image& out, dip::String const& interpolationMethod = S::LINEAR)  Computes the logpolar transform of the 2D image.

void dip::
Tile (dip::ImageConstRefArray const& in, dip::Image& out, dip::UnsignedArray tiling = {})  Tiles a set of images to form a single image.

void dip::
TileTensorElements (dip::Image const& in, dip::Image& out)  Tiles the tensor elements of
in
to produce a scalar image 
void dip::
Concatenate (dip::ImageConstRefArray const& in, dip::Image& out, dip::uint dimension = 0)  Concatenates a set of images along one dimension.

void dip::
Concatenate (dip::Image const& in1, dip::Image const& in2, dip::Image& out, dip::uint dimension = 0)  Concatenates two images.

void dip::
JoinChannels (dip::ImageConstRefArray const& in, dip::Image& out)  Concatenates a set of scalar images along the tensor dimension.

auto dip::
SplitChannels (dip::Image const& in) > dip::ImageArray  Splits the tensor elements of a tensor image into individual images.
Function documentation
void
dip::Wrap (dip::Image const& in,
dip::Image& out,
dip::IntegerArray wrap)
Shifts the input image by an integer number of pixels, wrapping the pixels around.
dip::Wrap
is equivalent to dip::Shift
with nearest neighbor interpolation and periodic
boundary condition, but faster.
void
dip::Subsampling (dip::Image const& in,
dip::Image& out,
dip::UnsignedArray const& sample)
Subsamples the input image.
The input image is subsampled by sample[ ii ]
along dimension ii
. The output image shares
the data segment of the input image, meaning that no data are copied. If a data copy is required,
calling dip::Image::ForceContiguousData
after subsampling should trigger a data copy.
If out
has an external interface different from that of in
, the data will be copied.
void
dip::Resampling (dip::Image const& in,
dip::Image& out,
dip::FloatArray zoom,
dip::FloatArray shift = {0.0},
dip::String const& interpolationMethod = "",
dip::StringArray const& boundaryCondition = {})
Resamples an image with the given zoom factor and subpixel shift.
The shift is applied first, and causes part of the image to shift out of the field of view.
Thus, shift
is in input pixels. boundaryCondition
determines how the new areas are filled in.
See dip::BoundaryCondition
. Note that the shift can be in fractional pixels. There is no largest
possible shift, but applying very large shifts is not optimized for, and will use more computation
and temporary memory than necessary. This is true even for the periodic boundary condition; use
dip::Wrap
to apply the integer shift with periodic boundary condition, then use Resampling
for
the remaining subpixel shift. The exception is the "ft"
interpolation method, which uses the same
memory and time for large as for small shifts.
The scaling is applied next. If zoom
is larger than 1, the output image will be larger than
the input, if it is smaller than 1, it will be smaller. The output image has size
std::floor( in.Sizes( ii ) * zoom[ ii ] )
along dimension ii
. For the "ft"
method, the zoom
factor is backcomputed from this output image size, whereas for the other methods the zoom
is used
as given. This stems from the very different approach to interpolation.
The pixel at coordinates pos
in the output image is interpolated from the position
pos[ ii ] / zoom[ ii ]  shift[ ii ]
along dimension ii
. Thus, with zoom
smaller
than 1, no lowpass filtering is applied first. Again, the "ft"
interpolation method is different:
the output image is generated by inverse Fourier transform from the manipulated frequency spectrum
of the input image. The "ft"
method thus has lowpass filtering builtin when zooming out.
The output image has the same data type as the input image.
See Interpolation methods for information on the interpolationMethod
parameter.
void
dip::ShiftFT (dip::Image const& in,
dip::Image& out,
dip::FloatArray shift = {0.0})
Modulates the input Fourier spectrum to introduce a shift in the spatial domain
in
is the Fourier transform of an image img
. It will be multiplied with a complex quantity
to change its phase in such a way that the image img
will be shifted. For example:
dip::Image img = dip::ImageReadTIFF( "erika" ); dip::Image ft = dip::FourierTransform( img ); dip::ShiftFT( ft, ft, { 10.3, 5.2 } ); dip::Image shifted = dip::FourierTransform( ft, { "inverse", "real" } );
Produces the same output as:
dip::Image img = dip::ImageReadTIFF( "erika" ); dip::Image shifted = dip::Shift( img, { 10.3, 5.2 }, "fourier" );
void
dip::ResampleAt (dip::Image const& in,
dip::Image& out,
dip::FloatCoordinateArray const& coordinates,
dip::String const& interpolationMethod = S::LINEAR,
dip::Image::Pixel const& fill = {0})
Finds the values of the image at subpixel locations coordinates
by interpolation.
The array coordinates
must have all elements be arrays of the same length as the image dimensionality.
For any coordinates outside of the image domain, the pixel value fill
will be returned.
That is, no extrapolation is performed.
Coordinates match image indexing: the first pixel on a line has coordinate 0.
interpolationMethod
has a restricted set of options: "linear"
, "3cubic"
, or "nearest"
.
See Interpolation methods for their definition. If in
is binary, interpolationMethod
will be
ignored, nearest neighbor interpolation will be used.
out
will be a 1D image with the same size as the coordinates
array, and the same data type and tensor
shape as in
. To obtain results in a floatingpoint type, set the data type of out
and protect it,
see The “protect” flag.
void
dip::ResampleAt (dip::Image const& in,
dip::Image const& map,
dip::Image& out,
dip::String const& interpolationMethod = S::LINEAR,
dip::Image::Pixel const& fill = {0})
Resamples an image with subpixel locations specified by a coordinate map.
Returns an image of the same size as map
with pixels taken from in
at the subpixel coordinates
specified by map
. Each tensor element of map
specifies the location for an input dimension.
As such, it must have a number of tensor elements equal to in
’s dimensionality, and realvalued samples.
For any coordinates outside of the image domain, the pixel value fill
will be returned.
That is, no extrapolation is performed.
Coordinates match image indexing: the first pixel on a line has coordinate 0.
interpolationMethod
has a restricted set of options: "linear"
, "3cubic"
, or "nearest"
.
See Interpolation methods for their definition. If in
is binary, interpolationMethod
will be
ignored, nearest neighbor interpolation will be used.
out
will have the same size as map
, and the same data type and tensor shape as in
. If out
is protected,
its data type will not change, but the computations will still be performed in the data type of in
.
void
dip::Skew (dip::Image const& in,
dip::Image& out,
dip::FloatArray const& shearArray,
dip::uint axis,
dip::String const& interpolationMethod = "",
dip::StringArray const& boundaryCondition = {})
Skews (shears) an image
The image is skewed such that a straight line along dimension axis
is tilted by an angle of
atan( shearArray[ ii ] )
radian in the direction of dimension ii
. shearArray[ ii ]
thus represents
the subpixel shift of a line in the direction ii
with respect to the previous line along axis
.
Each image subvolume perpendicular
to axis
is shifted by a different amount. The output image has the same dimension as in
in the axis
direction, and larger dimensions in all other dimensions, such that no data are lost. The value of shearArray[ axis ]
is ignored. The origin of the skew is the central pixel (see Coordinate system origin).
The output image has the same data type as the input image.
See Interpolation methods for information on the interpolationMethod
parameter.
boundaryCondition
determines how data outside of the input image domain are filled in. See
dip::BoundaryCondition
. If it is "periodic"
, a periodic skew is applied. This means that
image lines are shifted using a periodic boundary condition, and wrap around. The
output image does not grow along dimension skew
.
void
dip::Skew (dip::Image const& in,
dip::Image& out,
dip::dfloat shear,
dip::uint skew,
dip::uint axis,
dip::String const& interpolationMethod = "",
dip::String const& boundaryCondition = {})
Skews (shears) an image
The image is skewed such that a straight line along dimension axis
is tilted by an
angle of shear
radian in the direction of dimension skew
. Each image line along dimension
skew
is shifted by a different amount. The output image has the same dimensions as
in
, except for dimension skew
, which will be larger, such that no data are lost.
The origin of the skew is the central pixel (see Coordinate system origin).
The output image has the same data type as the input image.
shear
must have a magnitude smaller than π/2. Note that the definition of shear
is different
from that of shearArray
in the other version of dip::Skew
, documented above.
See Interpolation methods for information on the interpolationMethod
parameter.
boundaryCondition
determines how data outside of the input image domain are filled in. See
dip::BoundaryCondition
. If it is "periodic"
, a periodic skew is applied. This means that
image lines are shifted using a periodic boundary condition, and wrap around. The
output image does not grow along dimension skew
.
void
dip::Rotation (dip::Image const& in,
dip::Image& out,
dip::dfloat angle,
dip::uint dimension1,
dip::uint dimension2,
dip::String const& interpolationMethod = "",
dip::String const& boundaryCondition = S::ADD_ZEROS)
Rotates an image in one orthogonal plane, over the center of the image.
Rotates an image in the plane defined by dimension1
and dimension2
, over an angle angle
, in radian.
The origin of the rotation is the central pixel (see Coordinate system origin).
The output image has the same data type as the input image.
The rotation is computed by three consecutive calls to dip::Skew
. See that function for the meaning of
interpolationMethod
and boundaryCondition
.
void
dip::Rotation2D (dip::Image const& in,
dip::Image& out,
dip::dfloat angle,
dip::String const& interpolationMethod = "",
dip::String const& boundaryCondition = S::ADD_ZEROS)
Rotates a 2D image
Calls dip::Rotation
, setting the dimension parameters to 0 and 1. Provides a simplified
interface for 2D images.
void
dip::Rotation3D (dip::Image const& in,
dip::Image& out,
dip::dfloat angle,
dip::uint axis = 2,
dip::String const& interpolationMethod = "",
dip::String const& boundaryCondition = S::ADD_ZEROS)
Rotates a 3D image in one orthogonal plane
Calls dip::Rotation
, setting the dimension parameters according to axis
. Provides a simplified
interface for 3D images.
void
dip::Rotation3D (dip::Image const& in,
dip::Image& out,
dip::dfloat alpha,
dip::dfloat beta,
dip::dfloat gamma,
dip::String const& interpolationMethod = "",
dip::String const& boundaryCondition = S::ADD_ZEROS)
Applies an arbitrary 3D rotation to a 3D image
Rotates a 3D image over the Euler angles alpha
, beta
and gamma
, by calling dip::Rotation
three times (i.e. using nine skews).
The first rotation is over alpha
radian around the initial zaxis. The second rotation is over beta
radian
around the intermediate yaxis. The last rotation is over gamma
radian around the final zaxis.
The rotation is over the center of the image, see Coordinate system origin.
void
dip::RotationMatrix2D (dip::Image& out,
dip::dfloat angle)
Creates a 0D (one pixel) 2x2 matrix image containing a 2D rotation matrix.
Multiplying the output of dip::CreateCoordinates
by this rotation matrix will produce
an image with a rotated coordinate system. The rotation matrix must be on the lefthandside
of the multiplication operator.
The rotation is over angle
radian. Note that when transforming a coordinate system
(a passive transformation), then the transpose of the matrix must be used.
out
is of type dip::DT_SFLOAT
by default.
Example:
dip::Image coords = dip::CreateCoordinates( { 256, 256 }, { "frequency" } ); dip::Image rotatedCoords = dip::RotationMatrix2D( dip::pi/4 ) * coords;
void
dip::RotationMatrix3D (dip::Image& out,
dip::dfloat alpha,
dip::dfloat beta,
dip::dfloat gamma)
Creates a 0D (one pixel) 3x3 matrix image containing a 3D rotation matrix.
Multiplying the output of dip::CreateCoordinates
by this rotation matrix will produce
an image with a rotated coordinate system. The rotation matrix must be on the lefthandside
of the multiplication operator.
The rotation is over the Euler angles alpha
, beta
and gamma
: the first rotation is over alpha
radian around the initial zaxis. The second rotation is over beta
radian around the intermediate
yaxis. The last rotation is over gamma
radian around the final zaxis. Note that when transforming
a coordinate system (a passive transformation), then the transpose of the matrix must be used.
out
is of type dip::DT_SFLOAT
by default.
Example:
dip::Image coords = dip::CreateCoordinates( { 50, 50, 50 } ); dip::Image rotatedCoords = dip::RotationMatrix3D( dip::pi/4, 0, dip::pi ) * coords;
void
dip::RotationMatrix3D (dip::Image& out,
dip::FloatArray const& vector,
dip::dfloat angle)
Creates a 0D (one pixel) 3x3 matrix image containing a 3D rotation matrix.
Multiplying the output of dip::CreateCoordinates
by this rotation matrix will produce
an image with a rotated coordinate system. The rotation matrix must be on the lefthandside
of the multiplication operator.
The rotation is over angle
radian about the axis defined by vector
. That is, vector
will
not be affected by the rotation. Note that when transforming a coordinate system (a passive
transformation), then the transpose of the matrix must be used.
out
is of type dip::DT_SFLOAT
by default.
Example:
dip::Image coords = dip::CreateCoordinates( { 50, 50, 50 } ); dip::Image rotatedCoords = dip::RotationMatrix3D( { 1.0, 0.0, 0.0 }, dip::pi/4 ) * coords;
void
dip::AffineTransform (dip::Image const& in,
dip::Image& out,
dip::FloatArray const& matrix,
dip::String const& interpolationMethod = S::LINEAR)
Applies an arbitrary affine transformation to the 2D or 3D image.
matrix
contains 4 values (in
is 2D) or 9 values (in
is 3D) representing a linear
transformation matrix. Optionally, a translation can be represented by 2 (2D) or 3 (3D)
values added to the end of matrix
. In this case, the matrix is an affine transform
matrix using homogeneous coordinates, but with the bottom row removed (which is expected
to be {0,0,1}
in 2D or {0,0,0,1}
in 3D). The values are stored in columnmajor order:
⎡ matrix[0] matrix[2] matrix[4] ⎤ T_2D = ⎢ matrix[1] matrix[3] matrix[5] ⎥ ⎣ 0 0 1 ⎦ ⎡ matrix[0] matrix[3] matrix[6] matrix[ 9] ⎤ T_3D = ⎢ matrix[1] matrix[4] matrix[7] matrix[10] ⎥ ⎢ matrix[2] matrix[5] matrix[8] matrix[11] ⎥ ⎣ 0 0 0 1 ⎦
The coordinates of each pixel in in
(the origin of the coordinate system is the central pixel,
see Coordinate system origin) is mapped through the transformation matrix to obtain its location
in out
. Although the algorithm actually uses the inverse of the matrix to transform
each coordinate in out
to obtain the location where to interpolate a value from. out
is given
the same size as in
.
interpolationMethod
has a restricted set of options: "linear"
, "3cubic"
, or "nearest"
.
See Interpolation methods for their definition. If in
is binary, interpolationMethod
will be
ignored, nearest neighbor interpolation will be used.
void
dip::WarpControlPoints (dip::Image const& in,
dip::Image& out,
dip::FloatCoordinateArray const& inCoordinates,
dip::FloatCoordinateArray const& outCoordinates,
dip::dfloat lambda = 0,
dip::String const& interpolationMethod = S::LINEAR)
Warps an image based on a set of control points using thin plate spline interpolation
inCoordinates
and outCoordinates
are two sets of points (they must be of equal size). The
point inCoordinates[ ii ]
will be moved to outCoordinates[ ii ]
, warping the image in
accordingly.
lambda
is the regularization parameter. By default it is zero, meaning that the control points
will be matched exactly in the input and output images. Increasing lambda
allows some error in
the location of the control points, and will result in a smoother interpolation.
interpolationMethod
has a restricted set of options: "linear"
, "3cubic"
, or "nearest"
.
See Interpolation methods for their definition. If in
is binary, interpolationMethod
will be
ignored, nearest neighbor interpolation will be used.
void
dip::LogPolarTransform2D (dip::Image const& in,
dip::Image& out,
dip::String const& interpolationMethod = S::LINEAR)
Computes the logpolar transform of the 2D image.
By default, out
will be a square image with side equal to the smaller of the two sides of in
. However,
if out
is protected (see dip::Image::Protect
), its sizes will be preserved, even if not forged.
The xaxis (horizontal) of out
is the logarithm of the radius, and the yaxis is the angle.
interpolationMethod
has a restricted set of options: "linear"
, "3cubic"
, or "nearest"
.
See Interpolation methods for their definition. If in
is binary, interpolationMethod
will be
ignored, nearest neighbor interpolation will be used.
This function is an integral part of the FourierMellin transform, see dip::FourierMellinMatch2D
.
void
dip::Tile (dip::ImageConstRefArray const& in,
dip::Image& out,
dip::UnsignedArray tiling = {})
Tiles a set of images to form a single image.
Input images are arranged according to tiling
. For example, tiling = { 3, 2 }
will generate an
output where three images are placed horizontally, and two vertically. In this case, up to 6 input images
can be given in in
. If in
has fewer images, the corresponding locations in out
will be zero. If in
has 6 images, they will be placed as follows:
 in[0], in[1], in[2]   in[3], in[4], in[5] 
That is, images are tiled rowwise, from left to right and then top to bottom. tiling
can have any number
of elements, it is for example possible to tile 2D images along the 4^{th} dimension.
If tiling
is an empty array (the default), then ceil(sqrt(in.size()))
images will be placed horizontally,
in however many rows are necessary to fit all images.
The input images must all have the same sizes, with the exception for the case where all images are tiled
along a single dimension, in which case their sizes can differ along that dimension (see dip::Concatenate
)
The input images must all have the same number of tensor elements. If their tensor representations do not
match, the output image will be a default column vector. If images are differing data types, the output will
be of a type that best can represent the input (see dip::DataType::SuggestDyadicOperation
).
void
dip::TileTensorElements (dip::Image const& in,
dip::Image& out)
Tiles the tensor elements of in
to produce a scalar image
The tensor elements of in
are arranged according to its tensor representation, along the first two
spatial dimensions. This produces a scalar image of size in.Size(0) * in.TensorColumns()
along the
horizontal dimension, and size in.Size(1) * in.TensorRows()
along the vertical dimension. The output
image has the same dimensions as in
along the third and further dimensions.
void
dip::Concatenate (dip::ImageConstRefArray const& in,
dip::Image& out,
dip::uint dimension = 0)
Concatenates a set of images along one dimension.
Input images are concatenated along dimension dimension
. They must all have the same sizes along all
dimensions except dimension
, where they can differ.
The input images must all have the same number of tensor elements. If their tensor representations do not
match, the output image will be a default column vector. If images are differing data types, the output will
be of a type that best can represent the input (see dip::DataType::SuggestDyadicOperation
).
void
dip::JoinChannels (dip::ImageConstRefArray const& in,
dip::Image& out)
Concatenates a set of scalar images along the tensor dimension.
Input images are individual tensor components in the output vector image. They must all have the same sizes and be scalar.
If images are differing data types, the output will be of a type that best can represent the input
(see dip::DataType::SuggestDyadicOperation
). out
will be a vector image with in.size()
samples per pixel.
dip::ImageArray
dip::SplitChannels (dip::Image const& in)
Splits the tensor elements of a tensor image into individual images.
The output array contains images that each point to the data in in
.