At the risk of sounding off topic:
For better processing photos and sometimes images, I use the free-to-download Fusion 8 (it was free when i downloaded it from the devs, blackmagicdesign) This is a node based compositing software for movies/tv, but works great for:
1) scaling down photos (because you don't want to upload 3MB huge .jpg's, and sometimes photoshop isn't good enough for scaling down photos)
2) and in the node, apply sampling filter of choice, from very sharp to more blurry (whatever happens to look the best in any case)
3) color correction (fun to remove/suppress color, very simple to do)
4) adjust gamma, brightness and bunch of other things with one node
5) output as .jpg image with a reasonable file size
Learning to use this software might have you scratch your head in the beginning, but once you know how, you can save your setup, and reuse it for your next photo or whatever.