[X] My Assistant

Hello, new uploder here.
I've already uploaded a couple of galleries so far but, both times, the uploaded images come out blurrier than what the original files look like on my PC.
I understand that some amount of compression is inevitable when uploading pictures on the web but I was wondering if there was somenthing wrong in the way that I uploaded the images.
More specifically I was wondering which file format was best when pubblishing the galleries.
So far I have always uploaded PNG files thinking that they held details better, so whenever I collected artwork online I always saved it on my PC, or later converted it, to a PNG format from its original JPG format.
But considering that the images come out blurry anyway, I was wondering if it was better to just leave them, and upload them, in their original JPG format.

Converting a lossy image to PNG will literally just make the file size bigger in 99.9% of cases.

Always upload the original files.

The gallery images always use rescaled lower-quality images unless the source image is a below a certain resolution and file size already (which is fairly low), so no matter the format you're likely to see slightly worse versions unless you use the archive/torrent to download the original files. That'll be the blurring you see. So just upload the original jpgs.

Don't needlessly convert between lossy and lossless (either ruins the quality or bloats the filesize), or lossy to lossy (worsens the quality rapidly).

Re-encoding lossless files (i.e. png>png) can sometimes be worth it for unnecessarily large files (i.e. black and white images encoded in a color format, unused alpha channels), but it's only with lossless-to-lossless that you're both not introducing quality loss or potentially increasingly the file size. Converting jpg>png or png>jpg (unless the file size is so massive that this is necessary) are pretty much always going to make things worse for other users though.

Never convert JPEG to PNG. The only thing this does is make the files larger.

I recommend keeping the original format.
If you want to reduce the file size, you can consider converting png into lossless webp (please note that it is lossless, not lossy webp).
Converting the jpeg will only reduce quality or increase file size, so keep it as is.