This generates .png images using yuml.me. I'd like you to simplify my bash script so that I can learn more bash syntax/style.

make-diagrams.sh

#!/bin/bash

download_yuml_image() {
  local file="$1"
  local output_directory="$2"

  instructions=$(tr "\\n" "," < <(cat $file))
  image_basename=$(basename $(echo $file | sed -E "s/(.+)\.yuml$/\1/"))
  image_filename="${output_directory}/${image_basename}.png"

  wget -O "$image_filename" "http://yuml.me/diagram/plain;dir:TB/class/$instructions"
  gm convert ${image_filename} -units PixelsPerInch -density 96x96 'xc:white' -flatten ${image_filename}
}

for file in manuscript/diagrams/class/*.yuml; do
  download_yuml_image "$file" "manuscript/images/Design"
done