Image pick-up device reads image pick-up signals of all the pixels of CCD2 once when an optical system is in light intercepted state. By comparing the image pick-up signal from each pixel with a first threshold value THL1, a possibly defective pixels are extracted. Thereafter, by reading the...http://www.google.com.tw/patents/US5854655?utm_source=gb-gplus-share專利 US5854655 - Defective pixel detecting circuit of a solid state image pick-up device capable of detecting defective pixels with low power consumption and high precision, and image pick-up device having such detecting circuit 
