When creating a build for an app, you will be asked to upload icon and splash screen. The following are the image dimensions and formats for the same.
App Icon Dimension : 1024 x 1024 pixels Format : PNG
Every app needs a beautiful, memorable app icon that attracts people in the App Store and stands out on their Home screen. This is required for displaying the icon on your mobile phones as well as publishing the app on app store & google play store.
Splash Screen Dimension : 2732 x 2732 pixels Format : PNG where the logo or other important artwork is placed within the centre 1200x1200 px
A splash screen is a graphical control element consisting of the window containing an image, a logo and the current version of the software used to capture the user's attention for a short time.As a promotion or lead-in to the site home page or to tell the user what kind of browser and other software they need to view the site.
Background image : 2208 x 2208 pixels Format : PNG where the logo or other important artwork is placed within the centre 1000x1000 px
This Image is set to the login and registration page in the background. By setting this Image, App looks very impressive.