filter2 {EBImage} | R Documentation |
Filters an image using the fast 2D FFT convolution product.
filter2(x, filter)
x |
An |
filter |
An |
Linear filtering is useful to perform low-pass filtering (to blur
images, remove noise...) and high-pass filtering (to detect
edges, sharpen images). The function makeBrush
is useful to
generate filters.
Data is reflected around borders.
If x
contains multiple franes, the filter will be applied one each frame.
An Image
object or an array, containing the filtered version
of x
.
Gregoire Pau, gpau@ebi.ac.uk
makeBrush
, convolve
, fft
, blur
x = readImage(system.file("images", "lena-color.png", package="EBImage")) if (interactive()) display(x, title='Lena') ## Low-pass disc-shaped filter f = makeBrush(21, shape='disc', step=FALSE) if (interactive()) display(f, title='Disc filter') f = f/sum(f) y = filter2(x, f) if (interactive()) display(y, title='Filtered lena') ## High-pass Laplacian filter la = matrix(1, nc=3, nr=3) la[2,2] = -8 y = filter2(x, la) if (interactive()) display(y, title='Filtered lena')