Twitter converts images into JPEGs. It's a lossy compression scheme that drastically reduces the filesize but with a slight drop in image quality. A lot of artists post to Twitter hours or days before they upload the unaltered files to Pixiv, so the lower-quality images tend to find their way here first. In a perfect world, we would always just be able to wait a little while and only post the Pixiv versions to Danbooru, but unfortunately, there's always the chance that the artist never cross-posts the image to Pixiv, so it's usually better to upload the Twitter version anyway just in case we lose our opportunity to archive it.
Twitter converts images into JPEGs. It's a lossy compression scheme that drastically reduces the filesize but with a slight drop in image quality. A lot of artists post to Twitter hours or days before they upload the unaltered files to Pixiv, so the lower-quality images tend to find their way here first. In a perfect world, we would always just be able to wait a little while and only post the Pixiv versions to Danbooru, but unfortunately, there's always the chance that the artist never cross-posts the image to Pixiv, so it's usually better to upload the Twitter version anyway just in case we lose our opportunity to archive it.
Twitter recently implemented a change and was explained on a Tweet the past month. While I am no expert or even in the slightest bit knowledgeable about this subject, I assumed that some images have little difference now vs the Pixiv counterparts to warrant re-uploading. I'll just take the opportunity to present this here, in case some users with ample knowledge can determine whether such images do not need to be uploaded.
At this point I'd like to ask. Do people really need to post from twitter and pixiv? Seems like one pic should be enough unless it's a revision.
Edit: If its a file size or fidelity thing I still think a conclusive reason to only post one of the pics can be agreed upon.
As to the first I know not enough to comment; but as to the last point I utterly agree; one version, the best, is always just enough.
If more than one version, or a number of useless variants, is presented at the same time, I cut the Gordian Knot by ignoring all of them. It is merely bad art not to know which is the final and best result one has achieved.
I'm no expert on the subject either, so hopefully someone more knowledgeable can offer some useful insight, but for now it looks like that change only applies to images that were originally uploaded as JPEGs. According to your source, PNGs bigger than 900x900 are still being converted into JPEG with slight reduction in quality.
Case in point: this image was compressed from the 2.34 MB PNG you see here to the 237 kB JPEG that is post #3738911. The differences are very subtle — the only one I noticed is some slight artifacting along the top/front of UMP45's hair, and it would be hard to spot anything else without using image tools to highlight the altered pixels. I'm not prepared to say whether such a minor difference is enough to matter.
Case in point: this image was compressed from the 2.34 MB PNG you see here to the 237 kB JPEG that is post #3738911. The differences are very subtle — the only one I noticed is some slight artifacting along the top/front of UMP45's hair, and it would be hard to spot anything else without using image tools to highlight the altered pixels. I'm not prepared to say whether such a minor difference is enough to matter.
This is the Twitter we all know and love, it is the clear-cut presentation of what you have mentioned on your first comment here, especially since the comparison is a PNG vs JPEG. The artifacts on the child can be easily seen for the most part.
post #3716904 & child - Here is an example affected with the new update implemented by Twitter, and another one by the same artist - post #3702309 and its Twitter counterpart. Now here is an example before the change got implemented - post #3692451 and Twitter. This what we are used to seeing from Twitter, a heavily compressed image enough to justify reuploading the Pixiv version if such compression is not present (the same as this post and the child).
These new Twitter posts seemed almost exactly identical to their Pixiv counterparts. My question now is, do such images need to be reuploaded? An unofficial tie-breaking rule was suggested in forum #160957 in the hopes of discouraging uploaders from uploading unnecessary duplicates. The post relationships wiki seems very outdated IMO. I want to know what anyone else thinks of this new update from Twitter.
