4K HD Wallpaper: Yellow Helicopter
The photography was taken by B. Hossfeld and from his courtesy can be downloaded free under CC0 license. Here's optimized for use in desktop backgrounds, homescreen phones, webdesign projects, apps...
Widescreen Desktop / Macbook (Retina): 2880x1800 (fits on: 2560x1600, 1920x1200, 1440x900)
High Definition HD 1080p: 1920x1080 (fits on: 1600x900, 1366x768, 1280x720)
Samsung Galaxy Tab & iPad: 2048x2048 (compatible with almost all tablets)