Detective quantum efficiency ($\mathrm{DQE}(q)={\mathrm{SNR}}_{\mathrm{out}}^2(q)/{\mathrm{SNR}}_{\mathrm{in}}^2(q)$)

detective quantum efficiency is the ratio of output to input squared signal-to-noise ratio for a specified measurement convention, often evaluated by spatial frequency. It describes information preservation by a detector rather than just its pixel size.