I use the desert theme at https://www.wildernessvoices.org.
Using GIMP I was able to determine exact dimensions for the graphic and then crop and alter some graphics I purchased at iStock photo to fit. I spent hours working on removing the text before deciding that “replace” was a far lesser pain than “modify”.
Using the most excellent support found here I then randomized several different pictures to appear.
GIMP is a good tool, multi-platform and free.
