SharpenLevel150 is a free and simple to use droplet that auto-levels, sharpens, sets bylines and sets resolution to 150 dpi using Graphic Converter app, then saves the modified files to a directory you specify as JPEGs.
NOTE: The droplet WILL NOT WORK unless you modify the path to the directory you want to save the images to inside the script. Launch AppleScript Editor (Applications > Utilities) and go File > Open.