Did a courtesy search of the forums and found nothing in the rules. I know we have the e6ai site, but is ai assisted upscaling permissible?

See ai_upscaled.

https://e621.net/help/uploading_guidelines

Bad Things To Upload:

[...]

• Low quality submissions: ... artificial upscales, AI/neural network edits, etc.
• Artificial upscales include anything like "normal" upscaling, waifu2x, neural network upscales, and similar.
• Sensible integer upscaling with nearest neighbor (a.k.a. without smoothing filters) is permitted for pixel artwork that would otherwise be too small to see well.

watsit said:
https://e621.net/help/uploading_guidelines

Another fine example of me skimming too hard. /o\

1 of those posts under ai_upscaled has been flagged as "previously deleted", i flagged 2 more since their source versions are already here (and they somehow still look better than the upscales), and then there's post #1585261 which i believe to be mistagged

I think it would be allowed in the same way that ai-generated artworks are rarely allowed due to very specific circumstances. For example, if someone generates an artwork using ai and then uses that as a reference I reckon this specific instance is allowed.

dripen_arn said:
1 of those posts under ai_upscaled has been flagged as "previously deleted", i flagged 2 more since their source versions are already here (and they somehow still look better than the upscales), and then there's post #1585261 which i believe to be mistagged

Perhaps, that post in particular, was upscaled using ai, and then it was manually edited by the artist to clean it up? I do say perhaps because I don't have no idea, this is not something I can see on the post.

wolfmanfur said:

Perhaps, that post in particular, was upscaled using ai, and then it was manually edited by the artist to clean it up? I do say perhaps because I don't have no idea, this is not something I can see on the post.

that post was uploaded in 2018, 5 years ago, and and even if there was a publicly available upscaler based on machine learning back then (which there wasn't) it wouldn'tv looked so good as to be debatable weather it's ai or not

while it would be nice to see the sort of people who use ai upscalers to touch up their art afterwards, what i think is more likely is that the source was simply really big and uncompressed to begin with and (evidenced by the source links ending in "raw.png")

dripen_arn said:
that post was uploaded in 2018, 5 years ago, and and even if there was a publicly available upscaler based on machine learning back then (which there wasn't) it wouldn'tv looked so good as to be debatable weather it's ai or not

while it would be nice to see the sort of people who use ai upscalers to touch up their art afterwards, what i think is more likely is that the source was simply really big and uncompressed to begin with and (evidenced by the source links ending in "raw.png")

Waifu2x has been around since at least 2015.

votp said:
Waifu2x has been around since at least 2015.

ah. i admit i didn't know that

i'm still convinced that it was tagged just because it was exceptionally high-res and lossless + the art style being a bit soft on the edges

watsit said:
https://e621.net/help/uploading_guidelines

I don't like to stir the pot to say but.. some artists are using AI to enhance their images. Proof is right on their twitter page, written by them, under their main account. A lot of their stuff is already posted on this site but it seems like the great war on AI is starting. I wont share names or posts publicly to cause drama but if mods or admins are interested (or janitors if they can do it) I can give proof to get AI art off this site.

an AI upscale would pretty much only ever be allowed in the extremely rare case if the original image had been lost and the upscale was the only remaining artifact.
I'd assume the hierarchy of quality is probably something like: full res original png >>> full res jpeg > lower res sample png/jpg > upres of original > upres of sample, there's obviously going to be exceptions to this, like 10 quality jpgs regardless of resolution and animations that use sick-inducing frame interpolation.

darryus said:
I'd assume the hierarchy of quality is probably something like: full res original png >>> full res jpeg > lower res sample png/jpg

The other way around. A lower res png is preferable to a full size jpg, unless the size disparity is really really significant (in which case, it may be best to have both). The color information alone on a jpg is 1/4th the resolution (half width and half height), but even at 4x the size, there can be additional noise, color shifting, and banding on a jpg.