Bull's eye color frequency plots

bullseye.R

library(jpeg)
library(rvest)

## Image urls
urls <- c(
  "http://www.instagram.com/p/BWIKgiuADnP/media/?size=m",
  "http://www.instagram.com/p/BXY2LnqgB-g/media/?size=m", 
  "http://www.instagram.com/p/BZhL7zlg0cE/media/?size=m", 
  "http://www.instagram.com/p/BaHDmk5AOYe/media/?size=m", 
  "http://www.instagram.com/p/BcDKJywAMh4/media/?size=m", 
  "http://www.instagram.com/p/Bcw-Uc1gWP9/media/?size=m", 
  "http://www.instagram.com/p/BdnYTPfglOO/media/?size=m", 
  "http://www.instagram.com/p/BfiqdRVgCxo/media/?size=m", 
  "http://www.instagram.com/p/Bg8q8fJAntj/media/?size=m", 
  "http://www.instagram.com/p/BiF9IP5F7bf/media/?size=m",
  "http://www.instagram.com/p/BiiF767Fc7O/media/?size=m", 
  "http://www.instagram.com/p/BkjPdUvFf8d/media/?size=m"
)

## Look at images
par(mfrow=c(4,3), mar=rep(0,4), bg='black')
imgs <- lapply(urls, function(session) {
  
  webpage <- html_session(session)
  url <- webpage$url
  
  ## Download image from url
  z <- tempfile()
  download.file(url, z, mode="wb")
  img <- readJPEG(z)
  file.remove(z) # cleanup
  
  ## Round RGB values to minimize number of total possible colors
  img = round(img, digits = 1)
  
  plot.new()
  lim <- par()
  rasterImage(img, lim$usr[1], lim$usr[3], lim$usr[2], lim$usr[4])
  
  return(img)
})

## Convert to "bulls-eye" plots inspired by http://hint.fm/projects/wired2008/
par(mfrow=c(4,3), mar=rep(1,4), bg='black')
invisible(lapply(imgs, function(img) {
  ## Convert from numbers to colors
  colors <- sapply(1:nrow(img), function(x) {
    sapply(1:ncol(img), function(y) {
      rgb(img[x,y,1], img[x,y,2], img[x,y,3])
    })
  })
  ## Color frequency
  common.colors <- table(colors)
  
  ## Plot common colors
  #t <- quantile(common.colors, 0.5)
  #t
  #common.colors <- common.colors[names(which(common.colors>t))]
  
  ## Plot top 10 colors
  common.colors <- sort(common.colors, decreasing=TRUE)[1:10]
  
  library(plotrix)
  radius = common.colors/max(common.colors)
  plot(0,0, xlim=c(-1,1), ylim=c(-1,1), axes=FALSE, xlab=NA, ylab=NA)
  lapply(1:length(radius), function(i) {
    draw.circle(0, 0, radius = radius[i], col=names(radius)[i], lty=0)
  })
}))