An image processing system which processes an image signal, and determines, extracts and corrects defective pixel signals from defective pixels in a sensor array including a plurality of pixels. A given pixel signal from a pixel in the array is determined to be defective if it has a signal level below a threshold value, as determined by an extraction unit which then extracts each defective pixel signal from the defective pixels in the array. A block-forming unit forms positional information for each defective pixel having a defective pixel signal extracted by the extraction unit, with positional information for a group of such extracted defective pixel signals being formed into a block. A storage units stores, in units of blocks, positional information for the defective pixel signals. A correction unit corrects the defective pixel signals by using the positional information, in units of blocks, stored in the storage unit.