Convert RGB to greyscale

Convert a 3-band RGB raster to 1-band greyscale raster. Based on wvtool::rgb2gray.

rgb_to_greyscale(x, rgb = 1:3, coefs = c(0.3, 0.59, 0.11))

Arguments

x

A three-dimensional stars object with RGB values

rgb

Indices of RGB bands, default is c(1, 2, 3)

coefs

RGB weights, default is c(0.30,0.59,0.11)

Value

A two-dimensional stars object greyscale values

Examples

data(landsat)
plot(landsat, rgb = 1:3)
#> Error in image.stars(x, ..., axes = axes, breaks = breaks, col = col,     key.pos = key.pos, key.width = key.width, key.length = key.length,     main = NULL): rgb plotting not supported on this device
landsat_grey = rgb_to_greyscale(landsat)
plot(landsat_grey, breaks = "equal")