Imaging device
Frequency characteristics of an optical low-pass filter ( 2 ) are set in such a way that a first false color passing rate indicative of the rate of frequency components passing through a frequency component region not lower than the Nyquist frequency fa for the lowest sampling frequency fs among the sampling frequencies in the longitudinal, the lateral, and the oblique directions for each color in an image sensor ( 5 ), i.e. a frequency component region lower than one half of the Nyquist frequency fs of the sampling frequency fs of the image sensor ( 5 ), is not higher than a specified value. An output image signal is created from a pixel signal created by the image sensor ( 5 ) so that N pixel signals (N is real number of 2 or above) created by the image sensor ( 5 ) correspond to one output image signal.
1. An imaging device, comprising:
an imaging optical system with an optical low-pass filter having predetermined frequency characteristics;
color filters that separate an imaging light passed through the imaging optical system into predetermined color components;
an image sensor that photoelectrically converts the imaging light passed through the color filters to generate pixel signals; and
an output image signal generating unit that generates output image signals based on the pixel signals obtained from the image sensor, wherein
the frequency characteristics of the optical low-pass filter are set in such a way that a first false color passing ratio is not higher than a specified value, the first false color passing ratio indicating the ratio of frequency components allowed to pass through in a frequency component region not lower than the Nyquist frequency for the lowest sampling frequency among sampling frequencies in the longitudinal, lateral, and oblique directions for each color component in the image sensor, and lower than the Nyquist frequency for the sampling frequency of the image sensor, and
the output image signals are generated from the pixel signals generated by the image sensor so that N pixel signals (N is a real number of 2 or above) generated by the image sensor correspond to one output image signal.
2. The imaging device according to claim 1 ,
the first false color passing ratio is set to 0.4 or below.
3. An imaging device, comprising:
an imaging optical system with an optical low-pass filter having predetermined frequency characteristics;
color filters that separate an imaging light passed through the imaging optical system into predetermined color components;
an image sensor that photoelectrically converts the imaging light passed through the color filters to generate pixel signals; and
an output image signal generating unit that generates output image signals based on the pixel signals obtained from the image sensor, wherein
the frequency characteristics of the optical low-pass filter are set in such a way that a second false color passing ratio is not higher than a specified value, the second false color passing ratio indicating the ratio of frequency components allowed to pass through in a frequency component region not lower than the intermediate frequency between the Nyquist frequency for the lowest sampling frequency among sampling frequencies in the longitudinal, lateral, and oblique directions for each color component in the image sensor and the Nyquist frequency for the sampling frequency of the image sensor, and lower than the Nyquist frequency for the sampling frequency of the image sensor, and
the output image signals are generated from the pixel signals generated by the image sensor so that N pixel signals (N is a real number of 2 or above) generated by the image sensor correspond to one output image signal.
4. The imaging device according to claim 3 ,
the second false color passing ratio is set to 0.2 or below.
5. The imaging device according to claim 1 ,
N =( fs/Fs ) 2 ,
wherein fs is the sampling frequency of the image sensor and Fs is the sampling frequency of an output image formed by the output image signals.
6. The imaging device according to claim 3 ,
N =( fs/Fs ) 2 ,
wherein fs is the sampling frequency of the image sensor and Fs is the sampling frequency of an output image formed by the output image signals.