You can freehand this or use painter’s tape, and it would look especially nice with colors on the same side of the color ...
If you are stuck with a mix of frames and aren't looking to modify or replace them, you can also coordinate by matting the images in a standard color or way. Read the original article on House Digest.
To create a rustic yet chic bit of autumnal decor for your walls, head on over to Dollar Tree and pick up a sink mat for this ...