Can't use my custom icons


I have a really simple game i’ve created.
I want to use a custom icon and splash screen.

I generated the folder resources with

ionic cordova resources

But i get

ERROR: Missing source image for "icon" (sources: resources/android/icon.png, resources/android/icon.jpg, resources/android/icon.jpeg, resources/icon.png, resources/icon.jpg, resources/icon.jpeg)

I believe it is because i am using low-res icons, issued from simple screenshots of my game.
Design is really something i’m not good with, and i was wondering how can i “upgrade” the quality ?
I believe the size for the icon is around 1024x1024 and even more for the splash screen.

How can i design my own images with such a high resolution ?
Thank !
try to change your img resolution using this online tool it worked for me … please check