I use imageMagick (
http://www.imagemagick.org)
for creating thumbnails and resizing images. It's free and can
handle a fair amount of image formats
for example, to resize an image I would do the following,
first, create a .bat file, createResized.bat:
convert.exe %1 -resize 800x800 %2
then, in your code
<cfset string1 = '/C C:\whatever\createResized.bat
"#vNewFileName#" "#vNewFileNameResized#"'>
<cfexecute name="cmd" arguments="#string1#"
timeout="180"></cfexecute>
this is how I would resize something to not be greater than
800 pixels in any direction for example