You might see everywhere mentioning CryTek SSAO is "gray": https://learnopengl.com/Advanced-Lighting/SSAO​

OK, let me assume the following facts:

• There is no absolute correctness in AO.
• I am not talking about the later improvement of using hemi-sphere kernel.

By x2, flat walls of 0.5 and corners of 0.25 would become the more correct 1.0 and 0.5 (at least, hemi-sphere results in these). So, the question, why didn't CryTek simply multiply it by 2.

Thanks.

RTR4: “edges being brighter than their surroundings”. Edges were 0.75, by x2 and clamping to 1.0 they would be the more correct 1.0.

1 possible answer from RTR4: "Doing so causes a flat surface to be darkened, with edges being brighter than their surroundings. Nonetheless, the results are often visually pleasing."