MaxImageSize.scala

import sys.process._

def maxSize(dir: File): (Int, Int) = {
  val xs = dir.children(_.ext.toLowerCase == "png")
  ((0, 0) /: xs) { case ((w, h), x) =>
    val txt   = Seq("identify", x.path).!!
    val words = txt.split(" ")
    require(words(1) == "PNG")
    val sub = words(2)
    val j = sub.indexOf('x')
    val w1 = sub.substring(0, j).toInt
    val h1 = sub.substring(j + 1).toInt
    math.max(w, w1) -> math.max(h, h1)
  }
}

val dir = userHome/"Documents"/"devel"/"Grenzwerte"/"image_out"
assert(dir.isDirectory)

maxSize(dir) // (1395,1403)