Sprite Compression

Hello everyone..!!

I am developing a game where I provide different themes to choose from. I have 20 sprites in each theme, and 20 different backgrounds.

My question is what would be the best resolution and compression settings for all the 20 sprites and background sprites so that they are less in size but yet does not loose quality.

all the textures occupy 97% of the memory in log editor.

Textures 242.6 mb 97.3%

Complete size 249.2 mb 100.0%

The APK build size is around 27MBs which I belive to be around 15MBs

I have no idea about sprite compression, so please help me with it.

Thanks in advance..!!