Lockscreen Wallpaper Designer (currently on sale for US$0.99) is a clever little app that lets you make an attractive lock screen for your iOS device that keeps the date and time legible.
To use the app, grant it access to your photo library. Choose an image, and select a rounded, square or star shaped window. You can zoom, shrink or reposition the photo as you like. Finally, save it and then find the result in your camera roll. Save it as wallpaper and you're good to go.
LockScreen Wallpaper Designer
There's complex here. The app does its job and produces a nice result. It's just a simple solution to make your lock screen more readable and attractive. You can manually accomplish the same thing with many photo editors, but this is quick and easy.
Lockscreen Wallppaer Designer is a universal app that requires iOS 7 or later. It is optimized for the iPhone 5.