This is the best time of the year to get CameraBag, an extremely useful tool for altering photos. It won't let you create pictures, but it will let you change exposure, colour, add text overlays, resize and much more.
With the current sale, it's $14. You get permanent ownership and all of the four or so upgrades that will happen in the next twelve months. Extending that gets another discount.
The 'pro' version can do much the same with video, and costs about twice that. Getting another year cost me just under £10, and I'm delighted to give the developers the money.
Native versions for Windows and Macs, plus 95% of the former now works for photos under Wine on Linux.