PURPOSE: To save trouble of setting a position and magnification of a picture to be magnified by generating magnified position information and magnification information to magnify a picture of difference from a magnification signal generating circuit so as to magnify the picture of difference between two pictures.

CONSTITUTION: A video image representing no man resident in a television conference room is stored in advance in a picture memory 9. Then a video image representing a person taking a seat in the television conference room is sent from an A/D converter 3 to a comparator 10, the comparator 10 compares the video image representing no man resident in the television conference room with the video image representing a person taking a seat in the television conference room and sets a frame C surrounding the difference between the two video images. Thus, a frame D affording some margin with respect to the frame C an whose aspect ratio is the same ratio as that of the original video image is set and a horizontal and vertical position is obtained from a position of the frame D with respect to the entire pattern by a magnification signal generating circuit 11. Then the magnification signal generating circuit 11 generates a magnification signal 12, a horizontal magnification position signal 13 and a vertical magnification position signal 14 from those data and outputs the signals to a picture magnification circuit 4.