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Apparatus for correcting for defective pixels in an image sensor

  • US 5,381,175 A
  • Filed: 04/06/1993
  • Issued: 01/10/1995
  • Est. Priority Date: 04/10/1992
  • Status: Expired due to Term
First Claim
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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.

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