1/2-inch 7.2MPixel CMOS Image Sensor with 2.25µm Pixels Using 4-Shared Pixel Structure for Pixel-Level Summation. - Young Chan Kim; Yi Tae Kim; Sung Ho Choi; Hae Kyung Kong; Sung In Hwang; Juhyun Ko; Bumsuk Kim; Tetsuo Asaba; Su Hun Lim; June Soo Hahn; Joon Hyuk Im; Tae Seok Oh; et al. (ISSCC, 2006)