Huawei P9 Lite - Manual (Page 125)

Camera and Gallery
118
Touch the thumbnail to read the text in the image, and then touch to edit the
image.
Camera and video settings
Setting the photo and video resolutions
Increase the resolution for higher quality images and videos. However, larger resolution
images take up more space on your phone. Changing the resolution will also change the
image dimensions.
Some shooting modes may not support all resolutions.
Open Camera. Swipe left on the screen and touch Resolution to change the
resolution.