PURPOSE: To visually display more than one next states linked with the visual display of the present state by selecting the convergence of the present state, the target next state, or an operation necessary for generating a final state.

CONSTITUTION: A camera 12 transmits a picture signal 12b to a frame capturing buffer 24. The buffer 24 transmits stored digital information to a display device processing unit 26 as a present image 24a. The processing unit 26 derives plural next camera images from the present image 24a, and outputs the present image and more than one derived camera images. This information is stored in a display device buffer 28, and transmitted to a display device screen 30. An area 30a of the display screen 30 displays the main present image. Areas 30b-30g respectively present an image in the next possible state derived from the area 30a. An operator selects one of those areas 30b-30g, resets the camera 12, and operates update based on the present image 30a.