Feature suggestion: Dither removal

[internetakias]

Hey, I'd like to suggest dither removal or undithering for waifu2x.
By the way, what prompted me to suggest this was the discovery that earlier versions of waifu2xcaffee, and I presume waifu2x were quite good at removing the dither from iDOLM@STER Cinderella Girls Starlight Stage cards using noise removal, but no so much anymore:
Original image:

2x Upscale w/ Level 2(High) Noise Removal using waifu2xcaffe 1.0.5:

2x Upscale w/ Level 2 Noise Removal using latest waifu2x (waifu2x caffe 1.0.7 gives similar results)

Actually, one interesting thing to note is that Level 2 noise removal actually removes less dither now than Level 1:

[nagadomi]

It seems that dither is not from JPEG compression. In latest filters, It is a detail.
However, I know that dither removal is very useful in this area.
I will add the level3 noise reduction filter that does not retain a detail, removing JPEG artifact and dithering noise.

You can get old filters at http://www.udp.jp/misc/waifu2x_models/v0.9/anime_style_art_rgb/ .

[internetakias]

Actually, would it be possible for dither removal to be separate from artifact removal, or would that not make that much of a difference?

[nagadomi]

Maybe it is possible. Of course, it has its limits.
I am planning to add -undither option.

[internetakias]

Thanks a lot, nagadomi!
Have some Starlight Stage card art to test the -undither option on https://icebluenoshunkan.kirara.ca/temp/ss/card_bg_png/200.html