초록 ▼

In the image pickup system of the present invention, factors that have an effect on noise such as the signal level, temperature of the CCD during shooting, exposure time, gain and the like are dynamically acquired, the noise level of the CCD is estimated, for example, for each pixel by a noise estim

In the image pickup system of the present invention, factors that have an effect on noise such as the signal level, temperature of the CCD during shooting, exposure time, gain and the like are dynamically acquired, the noise level of the CCD is estimated, for example, for each pixel by a noise estimating unit, and signal components equal to or less than this noise level in the video signals are suppressed by a noise reducing unit, so that a high-quality image that is substantially free of noise is obtained while preserving the edges of the image and the like.

대표청구항 ▼

1. An image pickup system comprising: a noise estimating unit for estimating the amount of noise contained in digitized signals from an image pickup element in which a plurality of pixels are arranged, for each pixel or for each specified unit area comprising a plurality of pixels; the noise estimat

1. An image pickup system comprising: a noise estimating unit for estimating the amount of noise contained in digitized signals from an image pickup element in which a plurality of pixels are arranged, for each pixel or for each specified unit area comprising a plurality of pixels; the noise estimating unit comprising: a parameter calculator for calculating parameters on the basis of at least one type of information selected from among a signal value level of the signals, a temperature of the image pickup element, a gain for the signals, and a shutter speed during shooting; anda noise amount calculator for calculating the estimated amount of noise on the basis of the parameters calculated by the parameter calculator;a noise reducing unit for reducing the noise contained in the signals on the basis of the amount of noise estimated by the noise estimating unit;color filters arranged at the front of the image pickup element; anda separating unit for separating the signals output from the image pickup element into signals for each of the color filters. 2. The image pickup system according to claim 1, wherein the noise estimating unit comprises an upper limit value setting unit for setting an upper limit value on the estimated amount of noise. 3. The image pickup system according to claim 1, wherein the noise reducing unit comprises: a threshold value setting unit for setting an amplitude value of the noise as a threshold value for each pixel or for each specified unit area comprising a plurality of pixels on the basis of the amount of noise estimated by the noise estimating unit; anda smoothing unit for reducing the amplitude component in the signals which are below the threshold value set by the threshold value setting unit. 4. The image pickup system according to claim 1, wherein the noise reducing unit comprises: a control value setting unit for setting control values used to control the frequency characteristics of the smoothing processing on the basis of the amount of noise estimated by the noise estimating unit; anda smoothing unit for performing smoothing processing that reduces a specified frequency band in the signals on the basis of the control values set by the control value setting unit. 5. The image pickup system according to claim 1, wherein the parameter calculator comprises a signal value calculator for determining the signal value levels by averaging a plurality of pixel values in one of a nearby region of a specified size and in the unit area that includes the pixel of interest. 6. The image pickup system according to claim 1, wherein the parameter calculator comprises a temperature sensor that measures a temperature of the image pickup element. 7. The image pickup system according to claim 1, wherein the image pickup element comprises an optical black (OB) region, and the parameter calculator comprises: a variance calculator for calculating the variance of the signals in the OB region; anda temperature estimating unit for estimating the temperature of the image pickup element based on the variance calculated by the variance calculator. 8. The image pickup system according to claim 1, wherein the parameter calculator comprises a gain calculator for determining the gain based on at least one type of information selected from among ISO sensitivity, exposure information and white balance information. 9. The image pickup system according to claim 1, wherein the parameter calculator comprises a shutter speed calculator for determining the shutter speed during the shooting based on exposure information. 10. The image pickup system according to claim 1, wherein the noise amount calculator calculates the amount of noise N using a signal value level L of the signals, a temperature T of the image pickup element, a gain G for the signals and a shutter speed S during shooting as parameters, and the noise amount calculator comprises: a coefficient calculator for calculating four (4) coefficients A, B, C and D on the basis of three (3) functions a(T, G), b(T, G) and c(T, G) using the temperature T and gain G as parameters, and a function d(S) using the shutter speed S as a parameter; anda function calculator for calculating the amount of noise N based on a functional equation N=(ALB+C)D defined by the four (4) coefficients A, B, C and D calculated by the coefficient calculator. 11. The image pickup system according to claim 10, wherein the noise amount calculator further comprises an assigning unit for assigning standard parameter values, and the parameters are values calculated by one of the parameter calculator, and standard values assigned by the assigning unit. 12. The image pickup system according to claim 1, wherein the noise amount calculator comprises: an assigning unit for assigning standard parameter values for parameters not obtained from the parameter calculator; anda look-up table 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.