A pixel array includes an array of pixels to receive light, a first pixel to be blocked from receiving the light, and a circuit to adjust signals output from pixels in the array based on a signal from the first pixel. The signals output from the pixels in the array include a first error value. The circuit reduces the first error value in the signals from the pixels in the array based on the signal from the first pixel. The circuit may also reduce a second error value in the signals output from the pixels in the array based on a signal from a second pixel. The first and second pixels may be outside of the pixel array. The first and second error values may be storage diode leakage value and a dark current value.