Resizing of images

For images resizing

#!/bin/bash

mkdir 640x480;
for i in `ls *.png`;
do convert -verbose -quality 65 -strip -resize 640x480 $i ./640x480/$i;
done;
echo FIN;

65

is the final quality (%)

640x480

is the final size. The image will be resized to meet one of the two dimensions but respecting the aspect ratio

640x480!

the size will be forced with no respect for the aspect ratio