The invention relates to an image processing device (1, 48, 51) including: several image signal inputs (2-9) for receiving a respective image input signal, the signals being unsynchronized; at least one image signal output (23-26) for emitting at least one image output signal; a combiner (22) for combining the different image input signals to form the image output signal; several synchronizers (14-21), which are respectively connected downstream of the image signal inputs (2-9) and which synchronize the unsynchronized image input signals; and several distorters or rectifiers for distorting or rectifying the individual image input signals before they are combined to form the image output signal. According to the invention, the distorters or rectifiers are formed by the individual synchronizers (14-21) and the image input signals are distorted or rectified independently of one another by one or more synchronizers (14-21). The invention also relates to an associated operating method.