Apparatus for correcting for defective pixels in an image sensor
First Claim
1. A solid state image pickup apparatus comprising:
- a solid state imager having a plurality of pixels which output analog signals corresponding to light incident thereon;
a sample and hold circuit for sampling and holding said analog signals output from respective pixels of said solid state imager in response to a sampling signal;
a low-pass filter connected to said sample and hold circuit for eliminating a high frequency component from the analog output signal of said sample and hold circuit so as to output a filtered signal;
an analog-to-digital converter connected to said low-pass filter for converting the filtered signal to a digital filtered signal;
a memory for storing position data indicative of a position of a defective pixel;
means for stopping supplying of said sampling signal to said sample and hold circuit in accordance with said position data so that the analog output signal from a respective defective pixel is replaced with the analog output signal from the pixel which is read immediately prior to the defective pixel;
interpolating means connected to said analog-to-digital converter for interpolating a digital signal in place of the digital signal corresponding to the position data indicating a defective pixel from digital signals corresponding to other pixels in surrounding relation to the defective pixel so as to generate an interpolated digital signal; and
switching means for selectively outputting the digital filtered signal and the interpolated digital signal in accordance with said position data.
1 Assignment
0 Petitions
Accused Products
Abstract
A solid state image pickup apparatus comprises a solid state imager having a plurality of pixels and which outputs a signal corresponding to light incident thereon, a sample and hold circuit for sampling and holding analog output signals from respective pixels of the solid state imager in response to a sampling signal, a low-pass filter connected to the analog output of the sample and hold circuit for eliminating a high frequency component therefrom so as to output a filtered signal, an analog-to-digital converter for converting the filtered signal to a digital filtered signal, a memory for storing position data indicative of a position of a defective pixel, a circuit for stopping the supply of the sampling signal to the sample and hold circuit in response to the position data indicating a defective pixel so that the output signal from the defective pixel is replaced with the analog output signal from a pixel read immediately prior thereto, an interpolating circuit connected to the analog-to-digital converter for interpolating a digital signal corresponding to the position data indicating a defective pixel by using the digital signals corresponding to other pixels surrounding the defective pixel so as to generate an interpolated signal, and a switch for selectively outputting the digital filtered signal and the interpolated signal in accordance with the position data.
-
Citations
4 Claims
-
1. A solid state image pickup apparatus comprising:
-
a solid state imager having a plurality of pixels which output analog signals corresponding to light incident thereon; a sample and hold circuit for sampling and holding said analog signals output from respective pixels of said solid state imager in response to a sampling signal; a low-pass filter connected to said sample and hold circuit for eliminating a high frequency component from the analog output signal of said sample and hold circuit so as to output a filtered signal; an analog-to-digital converter connected to said low-pass filter for converting the filtered signal to a digital filtered signal; a memory for storing position data indicative of a position of a defective pixel; means for stopping supplying of said sampling signal to said sample and hold circuit in accordance with said position data so that the analog output signal from a respective defective pixel is replaced with the analog output signal from the pixel which is read immediately prior to the defective pixel; interpolating means connected to said analog-to-digital converter for interpolating a digital signal in place of the digital signal corresponding to the position data indicating a defective pixel from digital signals corresponding to other pixels in surrounding relation to the defective pixel so as to generate an interpolated digital signal; and switching means for selectively outputting the digital filtered signal and the interpolated digital signal in accordance with said position data. - View Dependent Claims (2, 3, 4)
-
Specification