I bought my wife a large print of a painting of the five British owls. It was a good excuse to make a frame for it!
As it's so big (about 1500 x 900mm), I wasn't going to be messing around with mitres. It was wedged mortise and tenons for this.
I didn't take any in-progress photos, but, apart from the rebate (router table), the joinery was done by hand.
The shoulders on the tenon are offset front and back to account for the rebate:
I let in a couple of battens on the back to add a bit of stiffness and to help stop the picture and the MDF backer sagging. They're removable in case I ever need to take it apart (e.g. if I decide it's necessary to splash out on better glass).
Hopefully it will stay on the wall...
PS, the painting is by Jim Moir, better known as the comedian Vic Reeves.