Quickly make image(s) a given dimension by changing canvas size, not scaling.

normalizeicons.sh

#!/bin/bash

# Make the given file(s) the given dimension, by extending the canvas, rather 
# than scaling. Made especially for PNGs, since it makes the background 
# transparent and all. This programmer in particular has found it useful for 
# different-sized icons that end at their exact boundaries, causing headaches
# when developing Android apps.

# Name some args
FINALSIZE=$1

# Gotta have some parameters to continue
# First parameter should be image dimensions, i.e. contain 'x' in the middle.
if [ -z "$FINALSIZE" ] || [[ $FINALSIZE != *x* ]]; then
	if [[ $FINALSIZE != *x* ]]; then
		echo "desired-size not given!"
	fi
	echo "usage: normalizeicons.sh desired-size file [file2 ...]"
	echo "         desired-size: Desired image dimensions, e.g. 164x120"
	echo
	exit 1
fi

# Make sure we've got the magic butter
hash convert 2>/dev/null || { echo >&2 "MISSING convert COMMAND! INSTALL ImageMagick TO CONTINUE."; echo; exit 1; }

for INFILE in ${@:2}; do
	FILENAME=$(basename $INFILE)

	# Do the stuff
	# If your grays are fine, use this. Otherwise comment out, and use command below.
	convert $INFILE -background transparent -gravity center -extent $FINALSIZE $FILENAME

	# Sometimes this script messes up grays in your PNGs. If so, uncomment this:
	#convert $INFILE -define png:big-depth=16 -define png:color-type=6 -background transparent -gravity center -extent $FINALSIZE $FILENAME
done