Video signal processing apparatus, video signal processing method, and TV broadcast reception apparatus

A video signal processing method comprising:

• a first second-derivative calculation step of calculating a first second-derivative signal having a first peak frequency, in accordance with an HD video signal input as an HD-format signal;
• a second second-derivative calculation step of calculating a second second-derivative signal having a second peak frequency, in accordance with an SD up-conversion video signal input as the HD-format signal;
• an SD/HD video signal detection step of detecting whether an original video signal of the input HD-format signal is one of the SD up-conversion video signal and the HD video signal;
• a gain control step of controlling a gain for the first second-derivative signal and the second second-derivative signal on the basis of a determination result of the SD/HD video signal detection step;
• an addition step of adding the first second-derivative signal and the second second-derivative signal which are controlled in the gain control step;
• a nonlinear processing step of performing an amplitude limitation process and a coring process for the second-derivative signal output in the addition step, and controlling a gain of the second-derivative signal on the basis of a predetermined gain coefficient;
• and
• an output step of outputting a video signal which has undergone contour correction by adding the second-derivative signal processed in the nonlinear processing step and the input HD-format signal.

A TV broadcast reception apparatus comprising:

• a reception demodulation unit configured to receive a TV broadcast signal, and demodulate the TV broadcast signal into a video signal;
• a video signal processing unit configured to process the demodulated video signal;
• and
• a display unit configured to display the processed video signal,
• the video signal processing unit comprising
• a first second-derivative calculation circuit configured to calculate a first second-derivative signal having a first peak frequency, in accordance with an HD video signal input as an HD-format signal,
• a second second-derivative calculation circuit configured to calculate a second second-derivative signal having a second peak frequency, in accordance with an SD up-conversion video signal input as the HD-format signal,
• an SD/HD video signal detection circuit configured to detect whether an original video signal of the input HD-format signal is one of the SD up-conversion video signal and the HD video signal,
• a gain control unit configured to control a gain for the first second-derivative signal and the second second-derivative signal on the basis of a determination result of the SD/HD video signal detection circuit,
• an addition circuit configured to add the first second-derivative signal and the second second-derivative signal which are controlled by the gain control unit,
• a nonlinear processing unit configured to perform an amplitude limitation process and a coring process for the second-derivative signal output from the addition circuit, and control a gain of the second-derivative signal on the basis of a predetermined gain coefficient, and
• an output unit configured to output a video signal which has undergone contour correction by adding the second-derivative signal processed by the nonlinear processing unit and the input HD-format signal.