Aspects of the subject technology relate to electronic devices with displays. The display includes an array of display pixels and one or more display-light sensors that monitor the display light generated by the display pixels. Using the display-light sensors, corrections to control signals for the display pixels can be provided to correct for array non-uniformities and/or pixel degradation over time. The display-light sensors may be provided in an array of display-light sensors mounted parallel to the array of display pixels. The array of display-light sensors can be in-plane with the display pixels or vertically displaced from the display pixels. The display-light sensors may be prevented from receiving non-display light such as ambient light.