An apparatus and method for identifying aberrant pixels in an image sensor. The apparatus includes a light sensitive element configured to detect a first signal value representing a first level of an incident light and a light sensitive region separate from the light sensitive element configured to detect a second signal value representing a second level of the incident light. Comparing circuitry is configured to compare the first signal value and the second signal value and to output a signal indicating the pixel is an aberrant pixel if the first and second signal values differ by more than a maximum threshold value or less than a minimum threshold value in a threshold value range.