R/kmeans_pallette.R

In jrminter/rAnaLab: Helper Functions for the Analytical Laboratory

#' Construct a pallete from a PNG image
#'
#' Adapted from http://www.milanor.net/blog/build-color-palette-from-image-with-paletter/
#'
#' @param pngFile The png file to process
#'
#' @return a list ( rgb(k_means$centers))
#'
#' @import png
#' @import scales
#'
#' @examples
#' library(rAnaLab)
#' fi <- system.file("extdata", "rocks-in-the-river.png", package = "rAnaLab")
#' res <- kmeans_pallette(fi)
#' res
#'
#' @export
#'
kmeans_pallette <- function(pngFile){
  # adapted from
  # http://www.milanor.net/blog/build-color-palette-from-image-with-paletter/
  img <- readPNG(pngFile)
  dimension <- dim(img)
  img_rgb <- data.frame( x = rep(1:dimension[2], each = dimension[1]),
                         y = rep(dimension[1]:1, dimension[2]),
                         R = as.vector(img[,,1]), #slicing our array into three
                         G = as.vector(img[,,2]),
                         B = as.vector(img[,,3]))
  k_means <- kmeans(img_rgb[,c("R","G","B")], centers = 5, iter.max = 30)
  show_col(rgb(k_means$centers))
  ret <- rgb(k_means$centers)
  ret
}