I use Adobe Photoshop on my PC for most of my gfx.. I am still foggy on how I made my previous stuff, including my sig.. but I have used it to fix other pics that I have taken.. BlackBeard ain't got nothing on me.. lol (IYKYK)
I use Samsung Photo Editor on my tablet, it is so AWESOME at color correction.. I ended up using it to see if I could fix my photos from my trip to Niagara Falls, in which every one of my pictures had this really bad blue tint on them.. I mean, you would think that I had my camera wrapped in blue cellophane when I took the pics.. all I had to was open the pic in Samsung Photo Editor, and changed one setting and then saved it and the pic came out perfect.
I use Irfanview on my PC when dealing with images in batches.. for instance, whenever I take pics, be it with my phone, or my camera, always shoot high res, or as high as I possibly can without dominating the space on my SD cards.. and that always makes for excellent pics, however, when I need to resize them, be it for uploads or sharing with my family, then high res won't fit the bill, and since I am not going to try to resize them one by one in Photoshop, as it would take too long, this is where Irfanview comes in handy and it does its job very well.
I use MS Paint to edit screenshots that I have taken on my PC..
If I am editing a pic, or making a combined image then I will use Pixlr on my tablet.. it is like Photoshop in a way, but I use it for making collages of pics that I share with my family.. for instance, I once put a side by side image of me and my brother when we were babies, and about the same age, to show my siblings how much we looked alike as babies, and then I greyscaled the same pic and sent it to our Dad on Father's Day and it is better than a lot of the collage apps out there now..
Photobucket, used to have Pixlr as their web-based image editing tool, and it was awesome to use on the site, but when they did their site revamp, it was removed, and then replaced with some buggy program that couldn't hold a candle to Pixlr.. so I decided to see if they had a mobile app, and they did, and I haven't looked back since..