Image Quality

I uploaded some images and they got shrunk and converted to webp at a very low quality. What would be the best way to get the highest quality? I mean, in 2023, do we need to cut on kBs anymore? Is there a way to prevent the conversion?

The images are recompressed and scaled, that’s true, mostly to save storage space on our database (and the user’s quota).

Can you give me an example of the degradation? Like upload (or linking) the unscaled image in the forum and also a link to the scaled version of the site? I’d like to see the degradation myself.

webp in itself shouldn’t reduce the quality visibly, but the reduction of resolution will. Otoh, most users are using phones anyway and even when zoomed into the picture, they’re usually not sized so big that you can make out the difference.

In theory, I could offer an option for Sponsors to retain a better image quality. I had actually planned to add this when I implemented the image upload and scaling mechanism, but to my eyes, the image degradation was so minor, it didn’t seem necessary to me.

The third one is a webp of the same resolution I converted to webp myself. It takes less space and is much less jagged. It seems that maybe it’s the algorithm that shrinks the picture that is to blame.

Solved it. I downscaled and compressed the images myself before uploading and everything’s fine now.

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Indeed, the downscaling algorithm I’m using is certainly not the best available, so prescaling and converting it up front might be a better solution in some cases.

Your images are quite a challenge, the tie especially is revealing any flaw in an algorithm.

I wrote here because I thought there was something new. But the new thing is me actually creating collages like I used to a long time ago instead of inlining the pictures. Because the inlined pictures used to show up at their original size (which I think is the same on my mafistories site) I took the habit of prescaling them. So since they were already small, there was no issue. So I noticed this time because I didn’t prescale, and also because yes, the images were a bit challenging for nearest-neighbor sampling.

Images will only be scaled if you upload them to the site. If you link to them, they’ll not be scaled obviously.

And they have always been scaled, the algorithm hasn’t changed. I’m using the simple Java I/O which is rather bad, I agree (probably nearest neighbor).

I could replace it with a better library, though. Maybe you could add a Feature Request so I don’t forget about it…

It’s not a priority. What I meant was that even the images I uploaded here instead of linking to them had either already been scaled for my own site, or I had scaled them before uploading because I needed to scale them even more than you do to not mess up the formatting (in the previous way of integrating pictures).

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