1. A method for determining an actual distance between two points of an image of an object displayed on a device, comprising: photographing the object and creating the image of the object by the device; measuring an object distance between the object and an imaging element of the device, and inserting the object distance into an information header of the image of the object; measuring a focal length of a lens in the imaging element of the device, and inserting the focal length into the information header of the image of the object; measuring a physical size of a pixel for the imaging element of the device, and inserting the physical size of the pixel into the information header of the image of the object; receiving a user's indication of a first point of the image of the object on a user interface of the device; converting the user's indication of the first point of the image of the object into a first pixel coordinate on the image; receiving a user's indication of a second point of the image of the object on the user interface of the device; converting the user's indication of the second point of the image of the object into a second pixel coordinate on the image; determining a pixel distance between the first pixel coordinate and the second pixel coordinate; determining, from the information header of the image, the object distance between the object and the imaging element of the device, the focal length of the lens in the imaging element of the device, and the physical size of the pixel for the imaging element of the device; determining an image distance between the first pixel coordinate and the second pixel coordinate according to the pixel distance and the physical size of the pixel; and determining the actual distance between the first point and the second point of the image of the object based on the image distance, the object distance, and the focal length.