setopt PIPE_FAIL

local resize_by
local img
resize_by="$1"
shift
for img in $*
do
	echo "Processing ${img} ..."
	# mostly to remove the alpha channel so ocrmypdf can work with it
	# does not seem to work all the time, so 'convert' is used as well below
	# still nice to optimize
	optipng "${img}"
	if [ $? -ne 0 ]
	then
		echo "optipng failed"
		return
	fi
	# resize
	# and remove alpha channel so ocrmypdf can work with it
	# ocrmypdf does the quantization of the png which reduces size drastically
	convert -resize $resize_by% -alpha off "$img" - \
	| ocrmypdf - "$(basename $img .png).pdf"
	if [ $? -ne 0 ]
	then
		echo "convert or ocrmypdf failed"
		return
	fi
done