Colour quantisation through dithering techniques

Most colour image printing and display devices do not have the capacity to deal with true-colours. To display the image anyway, they need to apply a quantisation method to reduce the number of colours present into the image. The research of this article is directed towards the study of a special kind of quantisation methods known as dithering techniques. Several quantisation techniques already exist that produce good quality result but the results are still not perfect. A new method is proposed in this contribution based on the same principles as those pertaining to the Sigma-Delta modulators used in analogue-to-digital conversion. These ideas are extended to the two-dimensional image space. It is seen that because the noise-shaping filter can filter the quantisation noise more efficiently, the quality of the quantised image is improved. Furthermore, the complexity of the method remains comparable with the existing algorithms, as the error diffusion method.