What makes a great general-purpose photo does not necessarily make a great desktop background. Bright, busy photos — while they may be beautiful art pieces — are oftentimes a poor choice of background since they end up polluting your screen with a cacophony of overly stimulating visual noise. If all of your two million pixels are bright colors screaming for attention it takes a non-trivial amount of processing to work out which of those pixels you want to focus on and to retain that focus as you work. Take for example this desktop sporting one of OS X Maverick’s built-in backgrounds.
Yikes. I’d elaborate on what’s wrong with this background choice but I’m afraid you wouldn’t be able to read it over the neon green nightmare screaming above. Let’s pick something else…
This background is a vast improvement. Not only is it a far more soothing tone of green it’s also far less visually busy. It succeeds at fading into the background and directing focus towards the task by subtly supporting and enhancing the foreground, exactly what any kind of background is supposed to accomplish. After all, it’s not a desktop foreground, it’s a desktop background, and it should stay true to what it is (unless you plan on dedicating your computer to being a $1000+ picture frame).