A method, a system, a device, a storage means, and a computer software product for sharpening colours in an image, in which a first colour component is interpolated and sharpened in such a way that the effect of the colour component is computed in different directions, the highest and/or lowest value of the computed values is selected to represent the greatest and/or smallest change, after which the colour component is sharpened, if the ratio between the highest and lowest values falls within predetermined limit values. The second colour component is sharpened on the basis of the sharpening of said first colour component. After the sharpening, the second colour component is interpolated, wherein the result is a sharpened and interpolated three-colour image.