1. An image processing apparatus which processes input image data and outputs the processed image data, comprising: a plurality of image processing units, including a first image processing unit with a fixed image processing capability and a second image processing unit with a variable image processing capability; an instruction unit, configured to instruct the second image processing unit to exhibit an image processing capability corresponding to an operation mode; and a control unit configured to supply the input image data to said plurality of image processing units, causing said plurality of image processing units to execute processing corresponding to the operation mode, to receive the image data processed by said plurality of image processing units, and to sort the processed image data in accordance with the operation mode, wherein said control unit is configured to realize image processing corresponding to the operation mode using at least said first image processing unit and said second image processing unit.