filter2 {EBImage}R Documentation

2D Convolution Filter

Description

2D convolution-based linear filter for images and matrix data.

Usage

  ## S4 method for signature 'Image, matrix':
  filter2(x, filter, ...)

  mkball(n, shape="step")
  mkbox(n)

Arguments

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.

Details

The convolution filter is based on fft transforms. If x is an array, the filter is applied per frame (as to images).

Value

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.

Author(s)

Gregoire Pau, gpau@ebi.ac.uk

See Also

Image, fft


[Package EBImage version 2.6.0 Index]