Image pickup system

Abstract

An image pickup system has a noise estimating unit which estimates the amount of noise contained in a digitized signal from an image pickup element composed of an array of a plurality of pixels, either for each pixel or for each specified unit area made up of a plurality of pixels, and a shooting conditions estimation unit which estimates the shooting condition when an image based on the signal is acquired. The amount of noise estimated by the noise estimating unit is corrected on the basis of the shooting conditions estimated by the shooting conditions estimation unit, and the noise in the signal is reduced on the basis of the corrected amount of noise.

1 . An image pickup system, comprising:
 a noise estimator for estimating an amount of noise contained in a digitized signal from an image pickup element composed of an array of a plurality of pixels, either for each pixel or for each specified unit area comprising a plurality of pixels;   a shooting condition estimator for estimating a shooting condition when an image based on said signal is acquired;   a correction unit for correcting the amount of noise estimated by the noise estimator based on the shooting condition estimated by the shooting condition estimator;   a noise reducing unit for reducing the noise in the signal based on the amount of noise corrected by the correction unit;   color filters arranged on a front surface of the image pickup element; and   a separating unit for separating the signal that is output from the image pickup element into signals for each color filter,   wherein the shooting condition estimator comprises:
 an image characteristic detector for detecting, based on the signal, characteristics of the image based on the signal; and 
 a regional estimator for estimating the shooting condition of respective regions when an image based on the signal is acquired, based on the image characteristics detected by the image characteristic detector. 
   
     
     
         2 . The image pickup system according to  claim 1 , wherein the image characteristic detector comprises at least one type of unit selected from among a specific color detector for detecting specific color regions as image characteristics from the signal, a specific brightness detector for detecting specific brightness regions as image characteristics from the signal, and a frequency detector for determining frequency information in local regions of a specified size as image characteristics from the signal. 
     
     
         3 . The image pickup system according to  claim 1 , wherein the image status estimator further comprises a down sampling unit for down sampling the signal, and the image characteristic detector detects the image characteristics of the image based on the signal down sampled by the down sampling unit. 
     
     
         4 . An image pickup system, comprising:
 a noise estimator for estimating an amount of noise contained in a digitized signal from an image pickup element composed of an array of a plurality of pixels, either for each pixel or for each specified unit area comprising a plurality of pixels;   a shooting condition estimator for estimating a shooting condition when an image based on said signal is acquired;   a correction unit for correcting the amount of noise estimated by the noise estimator based on the shooting condition estimated by the shooting condition estimator;   a noise reducing unit for reducing the noise in the signal based on the amount of noise corrected by the correction unit;   color filters arranged on a front surface of the image pickup element;   a separating unit for separating the signal that is output from the image pickup element into signals for each color filter;   wherein the noise estimator comprises:   a parameter calculator for calculating parameters based on at least one type of information selected from among a signal value level of the signal, a temperature of the image pickup element, a gain for the signal, and a shutter speed during shooting; and   a noise amount calculator for calculating the amount of noise based on the parameters calculated by the parameter calculator;   the noise amount calculator comprising:   an assigning unit for assigning standard values as standard parameter values for parameters not obtained from the parameter calculator; and   a look-up table unit for determining the amount of noise by inputting the signal value level, temperature, gain and shutter speed obtained from one of the parameter calculator and the assigning unit.   
     
     
         5 . An image pickup system, comprising:
 a noise estimator for estimating an amount of noise contained in a digitized signal from an image pickup element composed of an array of a plurality of pixels, either for each pixel or for each specified unit area comprising a plurality of pixels;   a shooting condition estimator for estimating a shooting condition when an image based on said signal is acquired;   a correction unit for correcting the amount of noise estimated by the noise estimator based on the shooting condition estimated by the shooting condition estimator;   a noise reducing unit for reducing the noise in the signal based on the amount of noise corrected by the correction unit;   the shooting condition estimator comprising:   an image characteristic detector for detecting, based on the signal, characteristics of the image based on the signal; and   a regional estimator for estimating the shooting situation of respective regions when an image based on the signal is acquired, based on the image characteristics detected by the image characteristic detector.   
     
     
         6 . The image pickup system according to  claim 5 , wherein the image characteristic detector comprises at least one type of unit selected from among a specific color detector for detecting specific color regions as image characteristics from the signal, a specific brightness detector for detecting specific brightness regions as image characteristics from the signal, and a frequency detector for determining frequency information in local regions of a specified size as image characteristics from the signal. 
     
     
         7 . The image pickup system according to  claim 5 , wherein the image status estimator further comprises a down sampling unit for down sampling the signal, and the image characteristic detector detects the image characteristics of the image based on the signal down sampled by the down sampling means. 
     
     
         8 . An image pickup system, comprising:
 a noise estimator for estimating an amount of noise contained in a digitized signal from an image pickup element composed of an array of a plurality of pixels, either for each pixel or for each specified unit area comprising a plurality of pixels;   a shooting condition estimator for estimating a shooting condition when an image based on said signal is acquired;   a correction unit for correcting the amount of noise estimated by the noise estimator based on the shooting condition estimated by the shooting condition estimator;   a noise reducing unit for reducing the noise in the signal based on the amount of noise corrected by the correction unit;   the noise estimator comprising:   a parameter calculator for calculating parameters based on at least one type of information selected from among a signal value level of the signal, a temperature of the image pickup element, a gain for the signal and a shutter speed during shooting; and   a noise amount calculator for calculating the amount of noise based on the parameters calculated by the parameter calculator;   the noise amount calculator comprising:   an assigning unit for assigning standard values as standard parameter values for parameters not obtained from the parameter calculator; and   a look-up table unit for determining the amount of noise by inputting the signal value level, temperature, gain and shutter speed obtained from one of the parameter calculator and the assigning unit.