1. An image processing unit ( 100 ) for generating, based on a number of input images (I R, I,I L ), a first output image (I* L ) and a second output image (I* R ), to be displayed on a stereoscopic display device ( 306 ) resulting in: a stereoscopic image in the case of a first observer ( 302 ) who perceives the first output image (I* L ) and the second output image (I* R ) substantially separate in a left and a right eye; and a monoscopic image in the case of a second observer ( 304 ) who perceives the first output image (I* L ) and the second output image (I* R ) substantially both in both eyes, characterized in comprising: an offset calculator ( 102 ) designed to calculate an offset image (&Dgr;I) based on a first one of the input images; an addition unit ( 104 ) designed to calculate the first output image (I* L ) by adding the offset image (&Dgr;I) with a second one of the input images (I); and a subtraction unit ( 106 ) designed to calculate the second output image (I* R ) by subtracting the offset image (&Dgr;I) from the second one of the input images (I).