DEVICE AND METHOD FOR SUB-BAND DECOMPOSITION OF IMAGE SIGNALS

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. A second summer computes the difference between the first median filter output signal and the second median filter output signal to provide a second sub-band signal, while a a third summer computes the difference between the second median filter output signal and the third median filter output signal to provide a third sub-band signal.