An image processing apparatus comprising: a plurality of input terminals (IN1 - IN4) to which a plurality of image transmitting apparatuses (10A- 10D) that transmit image data can be connected; a plurality of output terminals (OUT1 - OUT4) to which a plurality of image receiving apparatuses (30A- 30D) that receive image data can be connected; an image processing section that converts image data inputted from any of the plurality of input terminals (IN1 - IN4), to a processing resolution and outputs the converted image data from any of the plurality of output terminals (OUT1 - OUT4); a selecting section that selects a combination of one of the input terminals (IN1 - IN4) to which image data is to be inputted and one of the output terminals (OUT 1 - OUT4) from which the image data is to be outputted; and an output setting section that sets an output set resolution for each of the plurality of output terminals (OUT1 - OUT4), according to a user operation; characterized by: an input setting section that sets an input set resolution for each of the plurality of input terminals (IN1 - IN4), according to a user operation; and a resolution determining section that determines, for the selected combination of an input terminal (IN1 - IN4) and an output terminal (OUT1 - OUT4), an input set resolution set for the input terminal (IN1 - IN4) to be a processing resolution, only when an output set resolution of the output terminal (OUT1 - OUT4) is set to "Source"; and ignores the input set resolution set for the input terminal (IN1 - IN4) and determines the output set resolution set for the output terminal (OUT1 - OUT4) to be a processing resolution, when the output set resolution of the output terminal (OUT1 - OUT4) is set to other than "Source". a plurality of input terminals (IN1 - IN4) to which a plurality of image transmitting apparatuses (10A- 10D) that transmit image data can be connected; a plurality of output terminals (OUT1 - OUT4) to which a plurality of image receiving apparatuses (30A- 30D) that receive image data can be connected; an image processing section that converts image data inputted from any of the plurality of input terminals (IN1 - IN4), to a processing resolution and outputs the converted image data from any of the plurality of output terminals (OUT1 - OUT4); a selecting section that selects a combination of one of the input terminals (IN1 - IN4) to which image data is to be inputted and one of the output terminals (OUT 1 - OUT4) from which the image data is to be outputted; and an output setting section that sets an output set resolution for each of the plurality of output terminals (OUT1 - OUT4), according to a user operation; characterized by: an input setting section that sets an input set resolution for each of the plurality of input terminals (IN1 - IN4), according to a user operation; and a resolution determining section that determines, for the selected combination of an input terminal (IN1 - IN4) and an output terminal (OUT1 - OUT4), an input set resolution set for the input terminal (IN1 - IN4) to be a processing resolution, only when an output set resolution of the output terminal (OUT1 - OUT4) is set to "Source"; and ignores the input set resolution set for the input terminal (IN1 - IN4) and determines the output set resolution set for the output terminal (OUT1 - OUT4) to be a processing resolution, when the output set resolution of the output terminal (OUT1 - OUT4) is set to other than "Source".