ID and passport photo
Crop a photo to passport size on a white background, and get several copies on one photo-shop print. Private: everything happens on your phone, nothing is uploaded.
Drag the photo to move it. Fit your face inside the dotted oval, with a little space above your head.
For a good ID photo
Stand in front of a plain white or light wall in daylight, face the camera, no hat or sunglasses, neutral expression. Requirements differ by document: check with the office (e.g. Immigration for passports) before you print.