Patent ID: 7420622

Claim:
An image switching apparatus comprising: an image processing unit for switching and outputting a video signal from inputted video signals of a plurality of channels and performing effects on a video signal upon switching; a control unit for controlling said image processing unit; a main operation unit connected to said control unit through a communication channel and which is used to operate said image processing unit; and a sub operation unit which can be connected to said main operation unit through a communication channel to operate said image processing unit, wherein said image processing unit includes a main circuit block exclusively provided in said main operation unit and a sub circuit block for use with said sub operation unit, at least a part of a circuit of said sub circuit block being a common circuit made common to said main operation unit, said image processing unit includes mode setting means for setting the available mode of said image processing unit to the standard mode or the half-divide mode, said main operation unit does not transfer instruction from said sub operation unit to said control unit upon said standard mode, said main operation unit transfers instruction from said sub operation unit to said control unit upon said half-divide mode, said control unit controls said image processing unit in response to instruction from said main operation unit upon said standard mode and said control unit controls said image processing unit in response to instruction from said main operation unit and also controls said sub circuit block in response to instruction transferred to said sub operation unit from said main operation unit upon said half-divide mode.