Average HashをScalaで書いてみた

avhash.scala

import java.awt.image.{BufferedImage => BI}
import java.io.File
import javax.imageio.ImageIO

object avhash extends App {
  val (w, h) = (16, 16)
  def toHash(originFile: File) = {
    def toGray(originFile: File) = {
      val newImage = new BI(w, h, BI.TYPE_BYTE_GRAY)
      val g = newImage.createGraphics()
      try {
        g.drawImage(ImageIO.read(originFile), 0, 0, w, h, null)
        newImage
      } finally {
        g.dispose
      }
    }
    def pixels = (0 until h) flatMap (y => (0 until w) map ((_, y)))
    val gray = toGray(originFile)
    val raster = gray.getData
    val avg = pixels.foldLeft(0.0)((d, p) => d + raster.getSampleDouble(p._1, p._2, 0)) / (w * h)
    pixels.map(p => raster.getSampleDouble(p._1, p._2, 0) >= avg)
  }
  
  val bits = toHash(new File(args(0)))
  bits.map(b => if (b) "1" else "0").grouped(w).foreach(l => println(l.mkString))
}

gistfile1.txt

以下のサイトを参考にしました。

簡単な画像の類似度計算手法「Average Hash」
http://www.toyamaguchi.com/blog/archives/20120731_average_hash/