Imagemagick Mogrify/Resize image to nearest power of two

power-resize.sh

#!/bin/bash
# Or add to ~/bash_aliases

magickpow2 () {
  echo Running imagemagick nearest pow with extension "$1"
  for file in $(find . -name "$1")
    do echo processing "$file"
    local powwidth=$(identify -format "%[fx:2^(floor(log(w)/log(2)))]" $file)
    if [ -z $powwidth ]
    then
      echo "$file" cannot be read
    else
      local powheight=$(identify -format "%[fx:2^(floor(log(h)/log(2)))]" $file)
      mogrify -resize "$powwidth"x"$powheight" $file
      echo $file resized to "$powwidth"x"$powheight"
    fi

  done
}

# Usage:
magickpow2 '*.png'