Half Quad Photodiode (QPD) for improving QPD channel imbalance. In one embodiment, an image sensor includes a plurality of pixels arranged in rows and columns of a pixel array that is disposed in a semiconductor material. Each pixel includes a plurality of subpixels. Each subpixel comprises a plurality of first photodiodes, a plurality of second photodiodes and a plurality of third photodiodes. The plurality of pixels are configured to receive incoming light through an illuminated surface of the semiconductor material. A plurality of small microlenses are individually distributed over individual first photodiodes and individual second photodiodes of each subpixel. A plurality of large microlenses are each distributed over a plurality of third photodiodes of each subpixel. A diameter of the small microlenses is smaller than a diameter of the large microlenses.