I use a program for Android called Photo & Picture Resizer
It works well with the occasional ad. My pics are generally 5-6MB when taken...and I can set what size to bring the picture down to. For the forums I try to keep em at 200-300KB.
I have 1 issue with posting pics on the forum and it is my stubbornness that I am not sure if I will ever get around. I love the speediness of what these little mini computers aka smartphones can do. Take some pictures, resize them, shoot video, get on the internet, call up someone, etc. BUT, I hate typing on the forums using my smartphone. I grew up in the early days or personal computers and the internet. And I prefer typing my long, boring, and sometimes funny forum posts on a computer. So I'm kinda torn where I take and edit pics with my smartphone, transfer those pics to my temporary cloud storage, so I can type the message and post the pics on a computer. I know...it's weird!
I use the same app, and have the same frustration at typing and organizing a post on the smart phone. One thing that helps is the "voice to text" feature on the Google Virtual Keyboard - that can get a bunch of words in place, but sometimes leaves "word salad" that needs to be cleaned up. The other handy thing is with the new forum software we have, it's possible to upload pictures and start text in a draft post, and then with just a preview move over to a computer and see that same draft post for editing!