WebP Image Quality Issues

[zed140]

Just a question, it's me or the webp format also destroy image quality?

[Pickysaurus]

Webp can be "lossy" or "lossless" depending on if file size or quality is prioritised. It also varies depending on the quality of the original image. Because we're serving images for the web, small file size is slightly higher priority than quality. Otherwise the pages on the site will take a very long time to load.

[zed140]

In this case if I want post an image, it's preferable I post the original png instead of a already compressed jpg to reduce the final quality loss. Thank.

[lancegeis]

quite a bump on this subject, the webp compression borks the black level, artifacting pictures, but there is no real solution for this, others algos wont do better.

 

an example with a difficult picture to compress, the black is at the very limit, even downsizing gives crushed blacks. It's original size is fine however, so watch it in fullscreen by clicking the link

https://i.ibb.co/wLrh3ZG/2k-Skyrim-SE-2023-07-21-16-12-21-upscayl-4x-remacri.png -png

 

 

https://staticdelivery.nexusmods.com/images/1704/1798547-1717309647.png  - Webp

 

some artifacts.

 

 

Jpg max compression 4:2:0 84% quality has better shadow details, for the same size ! because it compresses the shadows progressively, reducing the perceivable black aureolas. Technically degrading the picture more, perceptually it is more correct. (but the rest of the picture is degraded much more than webp)

https://i.ibb.co/CtHFrfZ/2k-Skyrim-SE-2023-07-21-16-12-21-upscayl-4x-remacri.jpg -jpg 4:2:0 84% quality same size than webp, 290kb

 

Avif is slightly better but it has a server cost to compress for acceptable result, it's clearly less efficient.

JPEG XR preserves the black better without very annoying (still there, less perceivable) artifacts but at slightly higher size, 380 kb, at a specific compression ratio, too much and it breaks black, too high and it artifacts even more. Also, it cannot be read by some browsers.

 

After testing, webp is a logical choice for compression.

HOWEVER, we could have an option for a webp lossless hosting and browsing (nexus would always provide lossless pics when available, if someone hosted a lossless pic), at a price on top of the actual premium service. Like lossless audio on streaming platforms. If i remember correctly, many years ago, (2015-2017?) the pictures werent compressed that much and looked better. But it's maybe my memory.

I know, there is many 3rd party websites to host lossless pics, but it's a pain in the ass, to say the least. It would be comfortable to handle lossless pics on nexus and it could be another way to support this amazing modding platform.

2kSkyrimSE 2023-07-21 16-12-21_upscayl_4x_remacri.jxr

[SirCadsimar]

WebP is pain.

[NevverSWL]

The webp compression is either awful or Nexus is setting the amount with a very heavy hand. I upload my images as jpgs but, recently, have noticed a lot of artifacting in my uploaded images that were automatically converted to webp.  As an example, a jpg I uploaded at 783 kb got smashed down to an 101 kb webp file for a 1920x1080 image; that's excessive. Is this something that came about since the recent web site changes? I didn't have problems with images until fairly recently and what is going on now kind of defeats the purpose of even bothering to upload screenshots in the first place since they end up looking like trash.

 

My original jpg:

 

Nexus webp:

[JimboUK]

Look at this, the artifacts are painfully obvious, to be expected when a 1440p image is reduced from 1.6MB to 103KB, whatever setting is being used it's way too aggressive.  

https://www.nexusmods.com/newvegas/images/137127

It's so overdone that the image looks like the file was corrupt. 

If bandwidth savings need to be made wouldn't it be preferable to reduce the max upload size to 1MB and have people optimise their own images?

The original image for comparison. 

 

[NevverSWL]

On 12/5/2023 at 2:33 AM, Pickysaurus said:

Webp can be "lossy" or "lossless" depending on if file size or quality is prioritised. It also varies depending on the quality of the original image. Because we're serving images for the web, small file size is slightly higher priority than quality. Otherwise the pages on the site will take a very long time to load.

But it seems to me that the amount of compression is overdone. I understand about wanting to keep pages loading quickly, but this is excessive. I mean, Nexus is in the business of hosting files, mods and images, and the image part is falling far short. What's the point of posting an image I spent time on only to have it look like hell once it is uploaded to the web site? 

Here's an example where I uploaded a 377 kb 1920x1080 jpeg and Nexus crushed it down to 49 kb webp. It looks very bad. The image linked in the description is the original hosted on Imgur, originally 377 kb but 325 kb after Imgur processed it and they look the same to me, it's the Nexus webp compared to the original that looks awful. 

https://www.nexusmods.com/cyberpunk2077/images/103453

[LenaWolfBravil]

It may be my eyesight... but could you please highlight the differences? Because I don't see any.

This is not a joke, nor am I trying to troll you. Rather, I would like to determine where I am losing quality because I don't see any difference between your original and processed image. Is it my screen resolution? I use 1600x900. But even so, I should be able to zoom in and see the detail that looks different to you.

[NevverSWL]

Sure thing! I'm sure it's not as easy for you to pick out as they're not your images so you're not as familiar with them as I am. So, here are two sections of the one from that post with the Nexus webp image on the left and Imgur version on the right; I literally opened them full size in my browser from my post and took screenshots of the browser window and outputted them as 100% quality jpegs so you can get the most accurate look at what I am seeing, just open each image in a new window and magnify to 100% to see them full size. What I'm seeing is blurring, washed out and shifted color (most noticeable in the face) and compression artifacts (most noticeable in the second image on the toon's chest). Its face looks like mashed potatoes compared to the less compressed version and the prominence of the artifacts (look like squares) is very bad.

It might just be screenshots of a video game and not an online or print article, but I still take pride in what I produce here too; I spend time setting up the poses and lights and then doing whatever I feel I need to in Photoshop to get the results I want and to have the images compressed like this... ugh.