Desktop wallpaper is a cheap trick. It’s only purpose is to make your computer screen look pretty, but I have yet to come across a photo or a work of art that I found to be anything but distracting. There is very little difference between UI elements like windows and objects depicted in a picture behind the windows. If you can see it, your brain needs to identify it.
This is why, currently, my desktop looks like this:
In contrast, the top results in both Google and Bing for the search term “desktop wallpaper” are images of nature, people, or movies. Some are nice works of art, and worth having around, but they are decoration, not functionality. If you are spending time looking at your desktop without any windows open, what are you doing?
Consider this image, from the very SEO friendly named downloadfreedesktopwallpaper.net
It’s a nice image, reminds me of something we might find in a frame on an office wall with some pseudo-inspirational saying beneath it. There are a lot of blues, and greens, a shiny, reflective lake, and patches of reddish brown that remind me of farmland. It’s a picture that I could spend some time looking at, and probably would. Probably when I’m trying to concentrate on something else. I might look at the mountain and think I’d like to climb it, or look at the lake and think it’d be a nice day for a swim. I might start to think about the smell of the trees. Or, I might just glance at the picture, and momentarily forget what I’m working on.
Bright colors and pictorial elements in wallpaper are distractions, and take away from what you are actually trying to accomplish with the machine. I recommend switching to either a solid color like dark or light grey, or a type of dark textured background, like the one I’m using now. Both look nice, and fade into the background when they are supposed to. I’m not against spending time looking at photographs, but save it for a specific time. The best time to look at photos or art is when you have the time and cognitive resources to appreciate the art, and let it take your imagination where it wants to go.