Download image files from Chrome's Developer tools "Save All as HAR".

getimage.groovy

import groovy.json.*

def slurper = new JsonSlurper()
def text = new File('hoge.com.har').text
def root = slurper.parseText(text)

def getImage(address){
  def command = 'wget '  + address
  def proc = command.execute()
  proc.waitFor()
}

def entries = root.log.entries
entries.each {
  def orgurl = it.request.url
  def url = orgurl.toLowerCase()
  if(url.endsWith('jpg') || url.endsWith('jpeg') || url.endsWith('png')){
    try{
      getImage(orgurl)
    }catch(Exception e){
      println e
    }
  }
}