When you set the same image as a wallpaper on both your iPhone/iPad/iPod touch home screen and lock screen it will be automatically resized and zoomed in. This behavior is present on recent versions of iOS and it is quite annoying because there is no specific option to disable it.
Some of the resized images may look good, and others (especially pics with lots of objects and/or people) will be ruined by this automated resize. The good news is, a simple trick can prevent the wallpaper image from being zoomed in.
- In the Photos app find and open the image you want to set as wallpaper.
- Hide the editing and sharing options by tapping on the photo. This will add a black border around it.
- Now simply take a screenshot of it (this is done by pressing the Home and Power buttons at the same time).
- Open the screenshot you just captured from the Camera Roll in the Photos app.
- From the Sharing button select the “Set As Wallpaper” option.
This way, the phone won’t be resized, but as a minor disadvantage it will have a black border. Nevertheless, this is the only way to prevent the automatic resizing so in the end, it’s your choice if you want to use this method or not.