Patent ID: 7643039

Claim:
A method for scaling a color image, the method comprising: (a) converting input data produced by sampling a color image having pixels arranged in a first grid of pixels into output data resulting in a reproduction of the color image having pixels arranged in a second grid of pixels, the first and second grids being different, wherein each pixel of the input data and of the output data comprises a plurality of sub-pixels, each sub-pixel of a pixel being associated with a color component of the color image, and wherein converting input data comprises producing a sub-pixel of a color component of a pixel of the output data by filtering the sub-pixels of the corresponding color component of the pixels of the input data using a filtering function locally related to said sub-pixel of the output data; (b) determining a distortion in the sub-pixel produced, wherein in step (b) an intensity associated with the sub-pixel produced is determined, an intensity limited to a minimum or a maximum intensity of the sub-pixel produced is determined, and an error reproducing the distortion is determined on the basis of the difference between the intensity of the sub-pixel produced and the limited intensity; and (c) compensating the distortion determined in step (b) by imposing a reverse distortion on sub-pixels in pixels of the output data adjacent to the pixel having the sub-pixel produced, wherein in a step (c1), an overall error of the sub-pixel produced is determined on the basis of the error produced in step (b) and of a non-corrected error of a preceding sub-pixel produced, and wherein in a step (c2), the overall error determined is corrected by setting the intensities of the preceding sub-pixel produced and the subsequent sub-pixel produced, and wherein the non-corrected error is that part of the preceding sub-pixel's overall error that was not correctable during compensation of the preceding sub-pixel's distortion due to the corrected intensity for the preceding sub-pixel reaching the limited intensity.