"Some RGBC patterns increase sensitivity but can suffer from color aliasing. Color aliasing results in the wrong color appearing in an area of the image. For example, a color such as red or blue can appear in a part of the image that should be green. In another example of color aliasing, a small white line on a black or otherwise dark background that registers on individual pixels will be interpreted as a line containing single pixels of each of the primary colors registered. Color aliasing occurs at least partly due to the alignment of clear filters within an RGBC pattern. Image sensors with clear pixels are more prone to color aliasing because clear pixels do not produce any color information of their own other than the intensity of light."
So, the authors propose to reduce clear color filter from the prior art on Fig. 9A to one on Fig. 9B:
The company patent application US20160240579 "Stacked embedded SPAD image sensor for attached 3D information" by Tianjia Sun, Rui Wang, Tiejun Dai proposes to combine SPADs and regular RGB pixels in the same array:
