If you have time and patience to search for your own FREE art, WikiMedia Commons is an excellent source! I love vintage/fine art, and if you have time this is a treasure trove of art from the ages.
Try searching for time periods or famous artists you like and see if their art is on this common page. You can then use these public domain images for free under these terms.
I go there every month to select a handful of new pieces for my TV to display for our family based on topics we are studying in our homeschool. I love having the Frame TV for this very purpose.
1 – Photo Orientation
WHAT TO LOOK FOR WHEN CHOOSING ONLINE ART FOR YOUR FRAME TV
If a vertical piece speaks to you and you want to display it, you can always put it on a solid horizontal background.
When you find art, look for a piece that is at least or over 3840 pixels wide. This will be ideal and get you the sharpest image. Bigger is better!
2 – Images with high pixels
You’ll just need to be mindful that when you are selecting a piece, you have enough leeway on the top or bottom of the image.
3 – Cropping space