A method for deriving an output signal from an input video signal generated by an image sensor having an image formed on a part of it. The input video signal includes an image portion generated by the part of the image sensor on which the image is formed, and an external portion generated by the part of the image sensor on which the image is not formed. In the method according to the invention, the input video signal is received, the external portion of the input video signal is identified, and the output signal is generated from the input signal by replacing the external portion with a synthesized portion. The synthesized portion may set the external area to black level, to a predetermined luminance and/or hue, or to a luminance and/or hue adaptively determined in response to the image portion of the input signal. A position-dependent variation may also be imposed on the external area. The external area may also be rearranged to change the displayed location of the image. The method also includes various ways of identifying the external portion of the input video signal.