A method of reading out photocurrent. A readout integrate circuit (ROIC) is provided including an integration capacitor (Cint) having a charging electrode. The ROIC provides linear operation over a linear pixel output signal range when a voltage across Cint (Vint) is in a Vint range between Vlin1-cap and Vlin2-cap, and a non-linear operation range outside the Vint range. A reset voltage (Vrst) is applied to the charging electrode to reset Vint outside the Vint range. The photocurrent is integrated to generate integrated photocurrent during a frame including integrating from Vrst toward the Vint range to integrate background current into the non-linear operation range and integrating to a voltage within the Vint range to integrate scene current into the linear pixel output signal range. The integrated photocurrent is processed to generate a pixel output signal. The pixel output signal excludes some background current that was integrated into the non-linear operation range.