Patent ID: 7683963

Claim:
A method of distance estimation to be implemented using a digital camera including a lens unit, a user interface unit, an image sensing unit, a display unit operable to display a target whose distance is to be estimated, and a processing unit coupled to the lens unit, the user interface unit, the image sensing unit and the display unit, the method comprising: a) establishing in the processing unit reference dimensions that correspond respectively to different kinds of targets, and a set of predetermined distance values; b) selecting one of the reference dimensions according to the target whose distance is to be estimated through the user interface unit; c) enabling operation of the digital camera such that a clear image containing the target is captured through the lens unit and the image sensing unit; d) enabling operation of the processing unit to obtain a focal length corresponding to the clear image captured in step c); e) enabling operation of the processing unit to calculate an image dimension for each of the predetermined distance values with reference to the reference to the reference dimension selected in step b) and the focal length obtained in step d), wherein the image dimension is equal to the product of the reference dimension and the focal length divided by the corresponding distance value; and f) enabling the processing unit to control the display unit such that the distance values are shown on the display unit at positions based on proportions of the image dimensions calculated in step e), the distance values being shown together with the clear image containing the target, wherein the distance of the target can be estimated as one of the distance values corresponding to a dimension of the target contained in the clear image and shown on the display unit.