Image Manipulation, Part 4

bright_object.R

doInstall <- TRUE  # Change to FALSE if you don't want packages installed.
toInstall <- c("ReadImages", "reshape", "ggplot2")
if(doInstall){install.packages(toInstall, repos = "http://cran.r-project.org")}
lapply(toInstall, library, character.only = TRUE)

imageLoader <- function(url){  # This function takes a URL, and generates a data.frame with pixel locations and colors
  # Download to disk, load
  download.file(url, "tempPicture.jpg", mode = "wb")  # Stash image locally
  readImage <- read.jpeg("tempPicture.jpg")
  
  longImage <- melt(readImage)
  rgbImage <- reshape(longImage, timevar = "X3",
                      idvar = c("X1", "X2"), direction = "wide")
  rgbImage$X1 <- -rgbImage$X1
  return(rgbImage)
  }

##########
# Part 4 # Finding a bright object
##########

# Load NASA's image
rgbImage <- imageLoader("http://www.nasa.gov/images/content/694811main_pia16225-43_full.jpg")
with(rgbImage, plot(X2, X1, col = rgb(rgbImage[, 3:5]), asp = 1, pch = "."))

# Look at a region of only sand
sandOnly <- with(rgbImage, rgbImage[X2 > 1000 & X1 > -300, ])
with(sandOnly, plot(X2, X1, col = rgb(sandOnly[, 3:5]), asp = 1, pch = "."))

sandMean <- apply(sandOnly[, 3:5], 2, mean)  # Find typical sand color values
sandSD <- apply(sandOnly[, 3:5], 2, sd)
colorZ <- sweep(rgbImage[, 3:5], 2, sandMean, "-")  # How much do all colors
colorZ <- sweep(colorZ, 2, sandSD, "/")  # deviate from sand colors?
plot(density(rowSums(colorZ)))

# Plot a "binarized" image, based on color Z-scores
with(rgbImage, plot(X2, X1, col = rgb(colorZ>4), asp = 1, pch = "."))
points(830, -920, cex = 4, col = "RED")
# That little blue dot, at about 830, -920, is the anomaly! Science!

I found your code as a sample tutorial in stackoverflow, but I found this code is kind of out of data.

The ReadImages package is removed by cran, and substituted by the jpeg package. And the function is now readJPEG().

The result for the image loading might be a little bit different.

This is really a good example for image recognition, if it is okay, hope that you could update this code.

Thank you!