Generate a structuring element kernel

Returns an integer matrix of 0s and 1s suitable for use as kernel in $morph().

Usage

get_structuring_element(shape = "rect", size = 3L)

Arguments

shape

Character. Kernel shape: "rect" (all ones), "cross" (plus-shaped: centre row and column are ones, rest zeros), or "ellipse" (ones inside the inscribed ellipse, zeros outside).

size

Single positive odd integer for a square kernel, or a length-2 vector c(width, height) for a non-square kernel. Both width and height must be positive odd integers.

Value

An integer matrix with 0s and 1s, of dimensions height x width.

Examples

get_structuring_element("cross", 5L)
#>      [,1] [,2] [,3] [,4] [,5]
#> [1,]    0    0    1    0    0
#> [2,]    0    0    1    0    0
#> [3,]    1    1    1    1    1
#> [4,]    0    0    1    0    0
#> [5,]    0    0    1    0    0
get_structuring_element("ellipse", c(7L, 5L))
#>      [,1] [,2] [,3] [,4] [,5] [,6] [,7]
#> [1,]    0    0    0    1    0    0    0
#> [2,]    1    1    1    1    1    1    1
#> [3,]    1    1    1    1    1    1    1
#> [4,]    1    1    1    1    1    1    1
#> [5,]    0    0    0    1    0    0    0