Abstract: A device that receives and processes an image signal for sub-band decomposition of an image includes a first median filter that receives the image signal and processes signal values of pixel locations (x0, y0), (x0?1, y0), (x+1, y0), (x0, y0?1) and (x0, y0+1) of the image signal to provide a first median filter output signal. A second median filter receives the first median filter output signal and processes signal values at pixel locations (x0, y0), (x0?2, y0), (x0+2, y0), (x0, y0?2) and (x0, y0+2) of the first median output signal to provide a second median filter output signal. A third median filter receives the second median filter output signal and processes signal values at pixel locations (x0, y0), (x0?3, y0), (x0+3, y0), (x0, y0?3) and (x0, y0+3) of the second median filter output signal to provide a third median filter output signal. A first summer computes the difference between the image signal and the first median filter output signal to provide a first sub-band signal.

Abstract: A method for post-processing compressed image data for reducing blocking artifacts is suggested, in which a set of primary image data (PID) is decomposed into data sets (IID1, IID2) containing the fine structure of the image with structure being smaller than the blocking artifacts and without the blocking artifacts and structures being larger than or comparable to the blocking artifacts as well as the blocking artifacts, respectively. In the decomposition of the primary image data (PID) a non-linear filtering process (F1) is involved. After decomposition of the primary image data (PID) a filtering process (F3) can be applied to the set of intermediate image data (IID2) containing larger details of the image as well as the blocking artifacts. Therefore, in the process of filtering out the blocking artifacts, the fine structure of the image is not influenced.

Abstract: The present invention relates to a device and method for sub-band decomposition of an image signal (S), that includes a cascade with n sequential median filters (M1, M2, M3, M4) where n≧2, each having an input and an output, with the image signal (S) being fed to the input of a first median filter (M1) and the input of each median filter (M2, M3, M4) following the first median filter (M1) being connected to the output of the previous median filter (M1, M2, M3) in the cascade, and at least one linking element (SUB1, SUB2, SUB3, SUB4) having at least two inputs and one output, where one output signal of one of the median filters (M1, M2, M3, M4) or the image signal (S) is fed to each of the inputs and where a sub-signal (S1, S2, S3, S4) is available at the output.

Abstract: A method for post-processing compressed image data for reducing blocking artefacts is suggested, in which a set of primary image data (PID) is decomposed into data sets (IID1, IID2) containing the fine structure of the image with structure being smaller than the blocking artefacts and without the blocking artefacts and structures being larger than or comparable to the blocking artefacts as well as the blocking artefacts, respectively. In the decomposition of the primary image data (PID) a non-linear filtering process (F1) is involved. After decomposition of the primary image data (PID) a filtering process (F3) can be applied to the set of intermediate image data (IID2) containing larger details of the image as well as the blocking artefacts. Therefore, in the process of filtering out the blocking artefacts, the fine structure of the image is not influenced.