The Image Meter app is quite similar to the first app on this list. The only difference is that it basically allows you to take measurements on an existing image instead of using the phone’s camera. Unlike other apps on this list, this is not a real-time measurement tool as it uses photos to do all of its measurements. While it would be pretty cool to get accurate measurements just from a photo, it would be nearly impossible for a normal camera to capture any kind of usable data. This is exactly why you need some kind of reference point in order to derive the measurements.