Random telegraph signal (RTS) and 1/f noises in source followers are becoming a most important issue for low-light level applications of CMOS image sensors.In this paper, we propose a column-parallel signal processing techniques for reducing RTS and 1/f noise of in-pixel source follower using a switched histogram based RTS noise suppression and averaging (HRNSA) and a switched correlated multiple sampling differential averaging (CMSDA) where, the source follower transistor is switched between two levels.Experimental results show that a noise reduction method using switched MOSFET circuit reduces the RTS and 1/f noise of CMOS image sensors.