Original pics extracted directly from the game's assets.
Game CG included inside the game “淫紋の獅子騎士” (v1.4)”, all images were originally in 816×624 size, which is quite small.
The latest Real-ESRGAN image restoration model was used to upscale (4.0x, as the training model was designed for) and restore (denoise, restore details) most of the images.
It took Real-ESRGAN around 2 hours to crunch down all 275 images on my machine (Small input, shorter time).
All uploaded pics were compressed with PNG compression level 9.