A photo-detecting circuit including a photosensitive detector configured to accumulate photo-generated charges at a first node upon irradiation by light, a transfer circuit configured to establish a current path to the first node in response to a first scan signal being active, an integrating circuit configured to selectively operate in a first mode in which the integrating circuit operates as an integrator to integrate a photocurrent and transfer an integration result to a second node for readout or a second mode in which the first input terminal of the integrating circuit is in conduction with the second node, and a reset circuit configured to selectively supply a first voltage or a second voltage to the second input terminal of the integrating circuit as a reference voltage. The second voltage is greater than the first voltage.