- by Bjorn Roesbeke, 9 months agoRated 2 out of 5TLDR: This addon genuinly tries to do what it promises but Firefox defaults + servers = useless addon.
The addon does something, but it's not resulting in refusal of webp images.
By clicking the "W" button on the toolbar, the sent "Accept" headers either include or don't include "image/webp", but it's of no use at all if the default following is "*/*".
It's possible to change the value of the "image.http.accept" key in "about:config" to (for example)
but this addon will then not be able to change this value anymore.
Furthermore, websites such as Youtube (Google in general) just plain refuse to offer anything but webp, even if Firefox does not indicate support for it in the "Accept" header. You may need to fool these websites in assuming you're using an old browser by changing or emptying the "general.useragent.override" key.
Developer responseposted 9 months ago> The addon does something, but it's not resulting in refusal of webp images. ...
> Furthermore, websites such as Youtube (Google in general) just plain refuse to offer anything but webp, even if Firefox does not indicate support for it in the "Accept" header.
Hi Bjorn, the purpose of this extension is to discourage server farms from re-compressing PNG and JPEG images as WebP images on the fly to save bandwidth, since this complicates saving in the original formats. It is not a goal of this extension to prevent sites designed to serve WebP images from doing so.
> You may need to fool these websites in assuming you're using an old browser by changing or emptying the "general.useragent.override" key.
That might work, but some sites might serve less useful pages, so you'll have to test and see what is the best compromise.
- by Firefox user 12363114, 9 months agoRated 2 out of 5Worked for about 5 minutes and then failed, allowing webp files through. I thought it was great while it lasted. It might be that the web site anticipated the add-in and bypassed it's functionality of not recommending webp images.
Developer responseposted 9 months agoThe extension should discourage servers from recompressing JPG and PNG images as WebP images -- typically without changing the file name/extension. Can you share a URL of a page that recompresses JPG and PNG images despite the extension? Perhaps I can figure out a workaround.
In case the problem is cached images from a previous visit to the page, you can clear Firefox's web cache: https://support.mozilla.org/kb/how-clear-firefox-cache
Note: the extension doesn't block pages like https://developers.google.com/speed/webp/gallery1 from using WebP images when they are part of the design.