An electronic imaging system includes a method for calibrating an image sensor having a array of pixels each used in capturing an image, the method comprising the steps of capturing first dark floor values at a first time from substantially all of the pixels in the array, storing the first dark floor values, capturing second dark floor values at a second time from substantially all of the pixels in the array, using the first and second dark floor values to compute third dark floor values, using the third dark floor values when processing the captured image.