There are three different Image Quality settings you can choose from: Low, Medium, and High. 

We recommend the Low image resolution setting for devices under 2GB RAM.

To change the image quality 

From the Map, go to the Settings menu by tapping on the gear icon on the bottom left. 

In the middle, find the Quality settings. It will display your current image quality.

Tap it repeatedly to change your image quality setting. 

Hit DONE and have fun!