Topic: Automatic replacement of images from Bluesky results in lower-quality uploads? (Resolved)

Posted under General

Today I looked at what replaced the images that I once posted and noticed that in a couple of cases the new files are noticeably smaller than the originals I uploaded:

https://e621.net/post_replacements?search%5Bpost_id%5D=5397634
https://e621.net/post_replacements?search%5Bpost_id%5D=5310046

I'm not sure exactly, but it seems that these bots are for some reason configured to consider files with a certain link to be the best version, although in fact it's the other way around

Updated

nikopol said:
Today I looked at what replaced the images that I once posted and noticed that in a couple of cases the new files are noticeably smaller than the originals I uploaded:

https://e621.net/post_replacements?search%5Bpost_id%5D=5397634
https://e621.net/post_replacements?search%5Bpost_id%5D=5310046

I'm not sure exactly, but it seems that these bots are for some reason configured to consider files with a certain link to be the best version, although in fact it's the other way around

Hello! This is explained in the Bluesky sites and sources entry, as well as a stickied thread:
https://e621.net/wiki_pages/31895#bluesky
https://e621.net/forum_topics/56919

Bluesky is recompressing the original blob image again for the thumbnail view. This adds additional compression artifacts and actually increases the file size in some cases. You can see regions of visual difference using tools like Idem's Sourcing Suite: https://i.ibb.co/MzrWnyS/Untitled.png

Unfortunately, file size does not correlate neatly to quality due to a variety of reasons. We try to preserve files "as is" with exact data matches to the best quality public source, as any modifications will typically either needlessly increase file size, lose quality, or both. Any posts that lose visible information or change file types from the original are considered inferior versions and will be replaced.

song said:
Hello! This is explained in the Bluesky sites and sources entry, as well as a stickied thread:
https://e621.net/wiki_pages/31895#bluesky
https://e621.net/forum_topics/56919

Bluesky is recompressing the original blob image again for the thumbnail view. This adds additional compression artifacts and actually increases the file size in some cases. You can see regions of visual difference using tools like Idem's Sourcing Suite: https://i.ibb.co/MzrWnyS/Untitled.png

Unfortunately, file size does not correlate neatly to quality due to a variety of reasons. We try to preserve files "as is" with exact data matches to the best quality public source, as any modifications will typically either needlessly increase file size, lose quality, or both. Any posts that lose visible information or change file types from the original are considered inferior versions and will be replaced.

Oh, sorry, from the description of the replacement I thought that everything was done automatically. TIL, that BlueSky does such strange manipulations with files, and that the correlation between quality and file size is not direct. Next time I will try to extract truly original files with your method

nikopol said:
Oh, sorry, from the description of the replacement I thought that everything was done automatically. TIL, that BlueSky does such strange manipulations with files, and that the correlation between quality and file size is not direct. Next time I will try to extract truly original files with your method

The only way to get the true truly original files is to ask for them from the artist themselves.
Otherwise, you'd have to look elsewhere since social media sites like Twitter & Bluesky will always destroy the original files through compression (see howto:sites and sources for more info).