Pixel count from image files with preset threshold at 127

PixelCount.scala

if (!args.isEmpty) {
  println("Filename\t\tTotal\tBlack\tWhite")
  args map to_file filter only_real_file foreach { file =>
    val image = javax.imageio.ImageIO.read(file)
    val (height, width, total) = (image.getHeight, image.getWidth, image.getHeight*image.getWidth)
    val rgbs = for (y <- 0 until height; x <- 0 until width) yield image.getRGB(x,y)
    val black = rgbs map to_gray count if_under_threshold
    println("%s\t\t%d\t%d\t%d" format (file.getName, total, black, total - black))
  }
} else {
  println("Usage: scala PixelCount.scala [list of image file names]")
}

def to_gray = (rgb: Int) => ((rgb&0xFF0000>>16) + (rgb&0x00FF00>>8) + (rgb&0x0000FF))/3
def to_file = new java.io.File(_: String)
def if_under_threshold = (_: Int) < 127
def only_real_file = (_: java.io.File).isFile