Max Image size?

Sorry, i can’t find this in the help. Actually, i can’t find the help!

What’s the max image size that can be uploaded and what formats? Is there a file size limit or a max resolution or both?

What about offsite links to images, are they OK?



The maximum image size and file attachment/upload size is 4096 KB.

Authorized file extensions:
Screen Shot 2022-01-25 at 8.39.08 PM

This is a link to an image on Wikipedia.

The link is

Awesome. Could .webp be added to the list of image formats?


This is possible, but I’m curious about the reason for your inquiry. Is there a specific reason you’re wanting to upload this specific file format and asking about file size limits? I now know it’s Google’s image format, but I have never heard anything about it until I just looked it up.

Good question.

Firstly, this is more of a browser issue than a forum issue. Asuming, that the forum would just accept the format and create a link, it’s really whether users’ browsers can handle it?

A while back there was a bit of a tiff :slight_smile: between Apple and webp. At one point they put it into their browser, then they took it out, then back in. Now i don’t know. Perhaps someone here knows if Apple’s browser can display webp nowadays. That would be the main reason not to allow it, if it doesn’t work with Apple.

Otherwise I’m seeing wide compatibility with webp. All my mobile devices handle it without issue. Same for other desktops.

In answer to your question;

For about 2 years now, i switched to webp as my main lossy format for images. I use png for authoring/editing and webp for deployment/demos/web. I’ve got to the point where jpeg really annoys me. Every time i zoom in, there are those annoying artefacts; blocks, halos, rings, marks and noise - even on, so-called, high quality. Even the most moderately compressed webp has none of those and 95% webp’s are really quite nice.

Webps are smaller, but for me it’s more about an acceptable quality in a distributable format. When you’ve spent 8 hours rendering an image, converting it to jpeg feels like drawing a moustache on the Mona Lisa.

Just to point out, there are other formats that claim to be better than webp. Accepted, there probably are. But Webp has reached a certain level of compatibility and has wide support, except possibly with Apple.

Exactly. I’ve allowed it as an extension for upload here, but it will be based on the viewer’s browser whether the image can be displayed or not.

Excellent! thanks for that.

Just checked, the iPhone browser seems OK with Webp.

This is a tangent, but do you have an example handy showing a jpeg with problems that can be solved by webp? When I’ve seen direct comparisons between webp and jpeg (e.g. here) the webp often looks (to my inexpert eye) clearly worse at comparable compression levels, eliminating artifacts at the cost of eliminating all texture and detail from low-frequency areas of the image, and sometimes getting the colors wrong too. Obviously you have far more experience in this area than I do and so do many others who swear by webp, but I can’t help feeling doubtful.


I actually already saw that article. It’s correct in a technical sense (like signal to noise), but ignores how bad artefacts can look.

I’m going to use a picture of a palace. original is here.

JPG (1095k) compressed 95%
also here

WEBP (996k) compressed 95%
also here

Look at the detail of the pagoda dome roof against the sky and also the tree leaves. You’ll see the appalling artefacts in the JPG.



Feel free to take the original png (linked above) and experiment for yourself. You can reduce the worst and still keep JPG at 100%, but there are still some and the picture is large.

I’d be interested if you can make a ~1M jpg with no visible artefacts.

All these images appear correctly for me using Safari on MacOSX, both in the forum and the notification email sent to me via gmail viewed in Safari as well.

Other browsers may not show .webp - I’ve heard IE likely doesn’t work and I’d suspect Opera might have a problem also.

The image details look relatively the same to my eyes, although if I look closely I think I see what you mean by artifacting in the sky above the pixelated curve of the dome.

I personally wouldn’t have noticed any difference on casual view if it wasn’t pointed out directly, but if you can save space in file size that’s a good thing.

At least this post can work as a browser test!

IE is discontinued. I tried in Edge and everything’s fine. Not tested Opera.

Just to add regarding image format comparisons, it’s important not to use an image that’s started life already lossy compressed. For example, most phone pictures are already JPG. RAW would be a good format to start from, for example.

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I’m being kind to JPG here, by using 95% Quality. The default is usually around 85% and, with that, the artefacting is just horrible!

JPG 85% detail (642k)

WEB 85% detail (591k). You can start to see problems with webp here, but not nearly as bad as jpg

For the record, I’m not expressly pushing webp here, but looking for a broadly supported format for lossy images with good quality for file size.

I can see what you mean, and that’s what’s going to happen with any kind of compression.

I imagine in most usage hopefully the player isn’t zoomed in quite this far and won’t notice, but I have seen this happen when creating logos when I’m adjusting text that I’ve downloaded from a style site when it’s converted from PNG and then moving it around and making it bigger it can create those weird edges.

A problem with JPG is the way it works; first split the picture into 8x8 pixel tiles then compress. There’s just no way you’re not going to get problems on the edges of those tiles between them.

Of course, this wasn’t a design mistake, it was an innovation! It allowed images to be compressed in hardware available back in 1990.

You could use a C-Cube CL550 processor to compress images in real time ! For instance, video compression as motion-jpeg.

Yes, Safari on Mac and iOS are both on board.

Everyone should become acquainted with WebP image format | Can I use... Support tables for HTML5, CSS3, etc

Fair point, the webp does come off better in that comparison. I can’t make a JPEG look that good except at much larger file size (more than half the size of the original, in fact, which kind of makes it pointless to use compression at all). All the edges against a clear blue sky make the difference clearer than it would be in many images, but still, if you have a sensitive eye for compression artifacts, that makes a preference for webp quite understandable.