Alter some Images

We run a Sports League and at times take a ton of pictures. Some of the pictures are good... others not so good. We need someone to process these pictures, change their size to a standard 500 x 300 pixel, place our branding on the pictures, and save them to a dropbox folder. We will use shared dropbox folder and at times might simply take pictures of players and upload them to the dropbox folder for processing. Other times we take our main camera out and snap 100's of pictures in the hopes of getting some great action shots. We do not expect a ton of pictures every week, maybe just a a few. Yet we do expect to do this for some time to come. We've been doing the league for 14 years and plan to run it another 14 years.