Imager readout circuit comprising: an active reset stage of the integration capacitor equipped with a first current amplifier, a buffered direct injection bias stage of the photodetector equipped with transistors forming a second current amplifier, a switching circuit comprising a coupling stage integrated in the readout circuit, the switching circuit being controlled by control signals and being configured to: during a reset phase of the integration capacitor corresponding to a first state of said control signals: couple said first current source to the integration capacitor and activate the first current amplifier while uncoupling said second current source of the photodetector and deactivating the second amplifier, during an integration phase of a current from the photodiode and corresponding to a second state of said control signals, couple said second current source to the photodetector and activate the second current amplifier while uncoupling said first current source of the integration capacitor and deactivating the first amplifier.