To study the degradation of remote-sensing cameras in terms of responsivity, dynamic range, and imaging performance due to exposure to space radiation, a y-irradiation experiment was performed on a large eight transistor (8T) complementary metal-oxide-semiconductor (CMOS) color image sensor. An in-depth investigation was thus conducted on the mechanisms by which ionization damage degrades radiation-sensitive parameters (i.e., dark current, dark signal non-uniformity, output signal, saturated output, and responsivity) of an image sensor, in its red, green, and blue channels. The findings of this study will serve as a theoretical and technical basis for the design of large radiation-hardened 8T-CMOS image sensors for space-based remote-sensing satellites.