Image taking apparatus, correction circuit and correction method

A correction circuit comprising:

• a horizontal integration processing section configured to integrate a reference video signal in the direction of horizontal lines of an image represented by said reference video signal in order to find a signal-level sum of said reference video signal for each specific one of said horizontal lines to be used as a reference value of said specific horizontal line and to integrate an image taking video signal in the direction of said horizontal lines of an image represented by said image taking video signal in order to find a signal-level sum of said image taking video signal for each particular one of said horizontal lines to be used as an image-taking value of said particular horizontal line;
• a memory configured to store said reference values each computed for one of said horizontal lines of an image represented by said reference video signal;
• a correlation detection section configured to read out said reference values from said memory and finding a correlation value representing a difference between each specific one of said reference values and a particular one of said image taking values computed by said horizontal integration processing section as a particular image taking value for the same horizontal line as said specific reference value in order to compute a flicker component;
• a correction-value generation section configured to generate a correction waveform having a phase at least opposite to the phase of said flicker component computed by said correlation detection section;
• and
• an amplitude correction section configured to superpose said correction waveform generated by said correction-value generation section on every horizontal line of said image represented by said image taking video signal in order to eliminate said flickers from said image represented by said image taking video signal;
• wherein
• said reference video signal is a flicker-free video signal which is generated by an image taking device to serve as a video signal representing an image containing no flicker oriented in the vertical direction of said image taking device when a shutter speed equal to a multiple of the blinking period of light received by said image taking device has been set for an electronic shutter employed in said image taking device;
• and
• said image taking video signal is a video signal which is generated by said image taking device when a shutter speed determined in advance has been set for said electronic shutter.

A correction method comprising:

• a shutter-speed setting step of setting the shutter speed of an electronic shutter employed in an image taking device, which operates with timings based on a frame rate determined in advance and the total number of horizontal lines, to serve as an electronic shutter allowing said shutter speed to be adjusted;
• a signal generation step of generating a signal with the type determined in advance by carrying out an opto-electrical conversion process for each of said horizontal lines on received light during a period equal to the shutter speed set in said electronic shutter at said shutter-speed setting step;
• a video-signal generation step of generating a video signal from said signal generated at said signal generation step by adjusting the gain of said signal in order to provide said video signal with a level determined in advance;
• and
• a flicker elimination step of comparing an image taking video signal with a reference video signal in order to compute a flicker component contained in said image taking video signal as a component oriented in the vertical direction of an image represented by said image taking video signal in a flicker correction process of eliminating flickers contained in said image represented by said image taking video signal in accordance with said computed flicker component;
• wherein
• said image taking video signal is a video signal which is generated at said video-signal generation step when the blinking period of said received light is equal to the integral multiple of a frame rate and a shutter speed determined in advance has been set for said electronic shutter;
• and
• said reference video signal is a flicker-free video signal which is generated at said video-signal generation step when said blinking period of said received light is equal to the integral multiple of a frame rate and a reference shutter speed equal to integral multiple of said blinking period of said received light has been set for said electronic shutter.