An RGB signal from an input terminal is supplied to a triple over-sampling/sub-pixel control processing unit and a brightness signal generating circuit in which a brightness signal is generated. A brightness edge detection/judgment unit detects an edge from this brightness signal, judges the kind of the edge, fetches a coefficient select signal corresponding to the judgment result from a memory and supplies the signal to the control processing unit. A tap coefficient corresponding to this coefficient select signal is set in the control processing unit and a triple over-sampling processing is executed for each of RGB. For edge parts, R and B sub-pixels the timings of which are displaced by ±1/3 pixel from the input R and B sub-pixels and the pixel gravitys of which are displaced by ±1/3 or ±1/8 pixel in accordance with the kind of the edge are generated.