Following the review of Jinkou Gakuen 2 (Artificial Academy 2) and Custom Maid 3D 2 from Froi, I decided to compare the image quality of Custom Maid 3D 2 from different resolutions at the highest and lowest quality. The sample is as below. Check the image at 100% size to see the differences.
On the top is highest settings in the game and on the bottom is the lowest settings in the game. Each picture is rendered at 4K resolution. Full HD image is upscaled by 400% (200% horizontal and 200% vertical). HD image is upscaled by 900% (300% horizontal and 300% vertical.
The difference between each resolution is only on sharpness, unlike most other games which also shows deeper detail at 4K. However, due to the native of this game which uses 3D Anime Shader to render the character, the sharpness difference is very visible.The same applies with Anti Aliasing between No AA and 8x AA.