rgb2gray transforms colors from RGB space
(red/green/blue) into an matrix of grayscale values.
rgb2gray(img)3-dimensional array of numeric or integer values
A matrix of grayscale values.
The function takes a 3-dimensional array of
numeric or integer values as input (img) and
returns a matrix of grayscale values as output. The
grayscale values are computed as GRAY = 0.2989 *
RED + 0.5870 * GREEN + 0.1140 * BLUE. If the array has
a fourth dimension (i.e., alpha channel), the fourth
dimension is ignored.
# construct a sample RGB image as array of random integers
imgRed <- matrix(runif(100, min = 0, max = 255), 10, 10)
imgGreen <- matrix(runif(100, min = 0, max = 255), 10, 10)
imgBlue <- matrix(runif(100, min = 0, max = 255), 10, 10)
imgColor <- array(c(imgRed, imgGreen, imgBlue), dim = c(10, 10, 3))
# convert to gray
img <- rgb2gray(imgColor)