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nagadomi / waifu2x

Image Super-Resolution for Anime-Style Art
http://waifu2x.udp.jp/
MIT License
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Feature suggestion: Dither removal #66

Open internetakias opened 8 years ago

internetakias commented 8 years ago

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: bg_200065 2x Upscale w/ Level 2(High) Noise Removal using waifu2xcaffe 1.0.5: bg_200065 noise_scale level2 x2 000000 2x Upscale w/ Level 2 Noise Removal using latest waifu2x (waifu2x caffe 1.0.7 gives similar results) ee3d1cda-1b8f-4dee-cd2e-bf344c7ef859 Actually, one interesting thing to note is that Level 2 noise removal actually removes less dither now than Level 1: f83df70d-b693-41e4-c119-e93a5789b270

nagadomi commented 8 years ago

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 commented 8 years ago

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 commented 8 years ago

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

internetakias commented 8 years ago

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