1. A method comprising: reading a reset level of an active pixel with a first readout circuit, and concurrently, reading a reset level of a reference pixel with a second readout circuit, wherein the active pixel and the reference pixel are in a same column of a pixel array, and wherein the first readout circuit is not coupled to readout the reference pixel and the second readout circuit is not coupled to readout the active pixel; reading an image signal level of the active pixel with a first readout circuit, and concurrently, reading an image signal level of the reference pixel with a second readout circuit, wherein the image signal level of the active pixel is read during a concurrent readout of image signal levels of all active pixels in a row including an active pixel for each column of the pixel array; and generating a reduced noise image signal level of the active pixel with noise reduction circuitry based on the reset levels and the image signal levels of the active and reference pixels, wherein the first readout circuitry is coupled to transfer the reset level of the active pixel and the image signal level of the active pixel to the noise reduction circuitry through the first readout circuitry, and wherein the second readout circuitry is coupled to transfer the reset level of the reference pixel and the image signal level of the reference pixel to the noise reduction circuitry through the second readout circuit.