filter2 {EBImage} | R Documentation |
2D convolution-based linear filter for images and matrix data.
## S4 method for signature 'Image, matrix': filter2(x, filter, ...) mkball(n, shape="step") mkbox(n)
x |
An object of Image in Grayscale mode, a numeric
array or a matrix . |
filter |
A square matrix with odd dimensions. |
n |
A positive integer of length 1, specifying the size (number of rows and columns) of the returned square matrix. |
shape |
A character vector of length 1, with one of two values:
step for a step function, ball for a semisphere. |
... |
Further arguments. |
The convolution filter is based on fft
transforms.
If x
is an array
, the filter is applied per frame (as to images).
filter2
returns a transformed object of the same class as
x
.
mkball
and mkbox
return a square matrix that can be used
for the filter
argument of filter2
. Its dimensions
(number of rows and columns) are given by n
. For
shape="step"
, the entries of the matrix are the integers 0
and 1, and the 1s correspond to the interior of a circle of radius
n/2
around the center element of the matrix.
For shape="ball"
, the non-zero elements of
the matrix are z = sqrt(radius^2 - x^2 - y^2)
, a
parameterization of a semisphere.
Gregoire Pau, gpau@ebi.ac.uk