As Suke pointed I forgot posting the solution for this question. Sorry all.
After a lot of managements the solution was easy and it was the one google's one.
this link is where you can create all images for android project.
Go there and:
- insert your image and select all features
- download it
- replace all image formats (xxhdpi, hdpi, ...) in your drawable-xxhdpi, drawable xhdpi,... and mipmap-xxhdpi, mipmap-xhdpi,... folders.
- in manifest set the
android:icon = "@drawable/myicon"
this is how I did it
hope it helps