imager (version 0.31)

crop.borders: Crop the outer margins of an image

Description

This function crops pixels on each side of an image. This function is a kind of inverse (centred) padding, and is useful e.g. when you want to get only the valid part of a convolution

Usage

crop.borders(im, nx = 0, ny = 0, nz = 0, nPix)

Arguments

im

an image

nx

number of pixels to crop along horizontal axis

ny

number of pixels to crop along vertical axis

nz

number of pixels to crop along depth axis

nPix

optional: crop the same number of pixels along all dimensions

Value

an image

Examples

#These two versions are equivalent
imfill(10,10) %>% crop.borders(nx=1,ny=1)
imfill(10,10) %>% crop.borders(nPix=1)

#Filter, keep valid part
correlate(boats,imfill(3,3)) %>% crop.borders(nPix=2)