Patent ID: 8310592

Claim:
A signal processing apparatus for doubling the number of effective pixels of an input digital image in a predetermined direction, comprising: an interpolation filter for outputting an interpolation value of signal levels at positions of ¼ phase and ¾ phase between two original pixels of the input digital image adjacent in the predetermined direction; a phase shift circuit for outputting signal value of each of the two original pixels by shifting the phases of the signals of the two original pixels in the predetermined direction to ¼ phase and ¾ phase, respectively, between the two original pixels; an edge detection circuit for detecting an edge portion of the image from a signal level change of a plurality of pixels including the two original pixels of the input digital image in the predetermined direction; and a first signal selection circuit for outputting the output of the phase shift circuit when the edge is detected, and outputting the output of the interpolation filter when no edge is detected, based on the result of detection by the edge detection circuit.