Imaging apparatus and flicker detection method

Abstract

An imaging apparatus includes an imaging sensor, a control unit that instructs the imaging sensor to capture a first picture with a first charge accumulation time based on a light source having a first frequency and to capture a second picture with a second charge accumulation time based on a light source having a second frequency different from the first frequency, and a difference picture generation unit that generates a difference picture by using the first and second pictures.

1 . An imaging apparatus comprising:
 an imaging sensor;   a control unit that instructs the imaging sensor to capture a first picture with a first charge accumulation time based on a light source having a first frequency and to capture a second picture with a second charge accumulation time based on a light source having a second frequency different from the first frequency; and   a difference picture generation unit that generates a difference picture by using the first and second pictures.   
     
     
         2 . The imaging apparatus according to  claim 1 , wherein
 the difference picture is generated based on a difference in a luminance between the first and second pictures, and   the imaging apparatus further comprises a flicker detection unit that detects a flicker generation in the second picture based on the difference picture.   
     
     
         3 . The imaging apparatus according to  claim 2 , wherein the flicker detection unit detects the flicker generation in the second picture based on a fluctuation of a pixel value for the difference picture in a vertical direction to a scanning direction of the first and the second pictures. 
     
     
         4 . The imaging apparatus according to  claim 2 , wherein if a flicker is detected in the second picture, the control unit instructs the imaging sensor to capture a picture under a light source having the second frequency. 
     
     
         5 . An imaging apparatus, under an environment equipped with a light source having a first frequency or a light source having a second frequency different from the first frequency, the imaging apparatus comprising:
 an imaging sensor;   a control unit that instructs the imaging sensor to capture a first picture with a first charge accumulation time based on the first frequency and to capture a second picture with a second charge accumulation time based on the second frequency, the second charge accumulation time being different from the first charge accumulation time; and   a difference picture generation unit that generates a difference picture from the first and second pictures.   
     
     
         6 . The imaging apparatus according to  claim 5 , further comprising a flicker detection unit that obtains a luminance fluctuation frequency in a vertical direction of the difference picture, and when the luminance fluctuation frequency comprises a frequency corresponding to the first frequency, determines that a flicker caused by blinking of the light source having the first frequency is occurring in the second picture. 
     
     
         7 . The imaging apparatus according to  claim 6 , wherein if the luminance fluctuation frequency is substantially zero, the flicker detection unit determines that no flicker is occurring. 
     
     
         8 . The imaging apparatus according to  claim 6 , wherein
 the control unit instructs the imaging sensor to capture a plurality of pictures, and   when a situation where the luminance fluctuation frequency comprises a frequency corresponding to the first frequency continuing a predetermined number of times, the flicker detection unit determines that a flicker caused by blinking of the light source having the first frequency is occurring in the second picture.   
     
     
         9 . A flicker detection method, under an environment equipped with a light source having a first frequency or a light source having a second frequency different from the first frequency, the method comprising:
 a first capture step for capturing a first picture by an imaging sensor that is adjusted to a first charge accumulation time based on a first frequency;   a second capture step for capturing a second picture by the imaging sensor that is adjusted to a second charge accumulation time based on a second frequency; and   a difference picture generation step for generating a difference picture from the first and second pictures.   
     
     
         10 . The flicker detection method according to  claim 9 , further comprising a flicker determination step for obtaining a luminance fluctuation frequency in a vertical direction of the difference picture, and determining, when the luminance fluctuation frequency comprises a frequency corresponding to the first frequency, that a flicker caused by blinking of the light source having the first frequency is occurring in the second picture. 
     
     
         11 . The flicker detection method according to  claim 10 , wherein if the luminance fluctuation frequency is substantially zero, it is determined that no flicker is occurring. 
     
     
         12 . The flicker detection method according to  claim 10 , wherein
 the first and second capture steps are repeated a plurality of times, and   in the flicker determination step, when a situation where the luminance fluctuation frequency comprises a frequency corresponding to the first frequency continuing a predetermined number of times, it is determined that a flicker caused by blinking of the light source having the first frequency is occurring in the second picture.