If you want your app to be compatible on most of all devices, you will need to have different resolutions. For a background image, the dimensions can vary for devices, that is why Android Studio has the capability to have mdpi, hdpi, xhdpi, and xxhdpi. Each of these fit different devices to support all devices.
Here is a breakdown of what each of these dpi ratings are:
- ldpi (low) ~120dpi
- mdpi (medium) ~160dpi
- hdpi (high) ~240dpi
- xhdpi (extra-high) ~320dpi
- xxhdpi (extra-extra-high) ~480dpi
- xxxhdpi (extra-extra-extra-high) ~640dpi | Launcher icon only!
And, here is a breakdown of the resolutions for the dpi's:
320dp: Normal phone screen: 240x320 ldpi, 320x480 mdpi, 480x800 hdpi, etc.
480dp: Tweener tablet like the Streak: 480x800 mdpi
600dp: a 7" tablet: 600x1024 mdpi
720dp: a 10" tablet: 720x1280 mdpi, 800x1280 mdpi, etc.
My suggestion would be to make the best quality image, then use the tool below:
For the binaries for the tool, click here.
For the download, click here. (Download in .jar format)
For more information, click here. If this post has helped, please mark it as correct for future readers.