Determining the size of an object in an image of a scene displayed on a display screen

摘要

A data processing apparatus is arranged to automatically determine the real size of an object in an image of a scene displayed on a display screen. In response to a user input, an image of the scene is displayed on a display screen, and a virtual object representative of a real size object is establish at a first datum position. Data defining the first datum position is recorded. The size of the virtual object in the image is varied in response to a user input. Data representing the horizontal and vertical size of the virtual object relative to the displayed image at the first datum position is recorded. The virtual object is further displayed at a second datum position in the image in response to a user input. Data defining the second datum position is recorded. The size of the virtual object on the display screen at the second datum position is varied in response to user input. Data representing the vertical and horizontal size of the virtual object at the second datum position relative to the displayed image is recorded.