Swapping In-Game generated Still Life Paintings and Photographs for your own Images is possible with S3PE.
(Maybe I am crazy, and there is some really good reason why I haven’t heard about HOW to do this before. Because it is actually really, really easy. Why isn’t everyone talking about this? Please call me out if I am just making this up, but this is working for me, and it should work for you, too.)
This is not CC. This is not a default replacement. This does not require anyone to have a mod to use it or share it. Just S3PE and an image editing program with a DDS plug in. The images are shareable on lots or in household inventories and do not require any installation of any mod, override, or CC.
Want to know how to do this? This is what I did (picture heavy).
For the text post version, try here.