1. A method of pre-processing an image of an interlaced video image sequence before encoding, wherein the method comprises the following successive steps: deinterlacing said image into a deinterlaced image computing a complexity value representative of the complexity of said image; applying an erosion on said deinterlaced image to generate a first processed image; linearly combining said deinterlaced image and said first processed image depending on a first weighting coefficient (K) computed from said complexity value, said linearly combining step generating a mixed image; applying a dilation on said mixed image to generate a second processed image; and linearly combining said mixed image and said second processed image depending on said complexity value.