Could someone please explain what the basis is for tagging something with waifu2x? Are there certain tell-tale image artifacts?

Because it seems to me that the tag is widely misused. In this case it seems more likely to be a patreon reward, since the artist advertises it on pixiv #52731284.

Arcana55 said:

Could someone please explain what the basis is for tagging something with waifu2x? Are there certain tell-tale image artifacts?

Because it seems to me that the tag is widely misused. In this case it seems more likely to be a patreon reward, since the artist advertises it on pixiv #52731284.

@Arcana55 Generally you can tell something is upscaled using waifu2x when lines become kind of fuzzy at places. In this case, I can tell you 100% that the image at this resolution is not the reward, as I have that month's set. When downscaling the full-size rewards to compare with this one at a 1:1 ratio, I found that this one has blurring of details in places reminiscent of waifu2x upscales.

Also, basically any unsourced image that is exactly 2x larger than the sample is highly likely to be an upscale from waifu2x (which upscales in 1.6 to 2x).