Image Processing - Implementing Sobel Filter

Question

I\'ve got a task to implement Sobel filter which is, as you know, an image processing filter for edge detection. But unfortunately, I\'ve got no experience in image processi

Answer 1

You can do this in R with the raster package (oriented towards geographic data)

library(raster)
sobel <- function(r) {
    fy <- matrix(c(1,0,-1,2,0,-2,1,0,-1)/4, nrow=3)
    fx <- matrix(c(-1,-2,-1,0,0,0,1,2,1)/4 , nrow=3)
    rx <- focal(r, fx)
    ry <- focal(r, fy)
    sqrt(rx^2 + ry^2)
}

b <- brick("https://i.stack.imgur.com/Bnxa6.jpg")
plotRGB(b)
s <- stack(lapply(1:3, function(i) sobel(b[[i]])))
plotRGB(s)

# or
ss <- mean(s)
plot(ss, col=gray(1:10/10))

# or
bb <- mean(b)
sss <- sobel(bb)
plot(sss, col=gray(1:10/10))