This app was mentioned in 2 comments, with an average of 1.00 upvote
how about trying something more sophisticated and phone independent?
https://play.google.com/store/apps/details?id=com.badpigsoftware.advanced.gallery
lets you export and you choose image resolution. take half or whatever and export it
I use Gallery Pro (https://play.google.com/store/apps/details?id=com.badpigsoftware.advanced.gallery). It has the drawing feature which I also missed quite a bit.