An image sensor may be provided. The image sensor may be a high-capacitance image sensor or a dual-mode image sensor having a high-capacitance operational mode. A high-capacitance image sensor may include image detectors and associated unit cells. During operation, the image sensor may integrate image signals from each detector row using unit cells in multiple unit cell rows. The image sensor may integrate and readout image signals in an interleaved process that allows each detector row to capture image data using multiple unit cells. A dual-mode image sensor may operate in a similar manner to a high-capacitance image sensor when operated in the high-capacitance mode. The dual-mode image sensor may have switches interposed between unit cells to selectively couple and decouple the unit cells for switching between the high-capacitance mode and a normal operational mode.