<p>An image conversion unit (100) for converting an input image with an input frequency spectrum into an output image with an output frequency spectrum, the output frequency spectrum having more relatively high frequency components than the input frequency spectrum is disclosed. The image conversion unit comprises: means for providing (102) an intermediate image on basis of the input image; and combining means (104) for combining a high frequency signal with the intermediate image into the output image by means of error diffusion.</p>
