Re: Standardisation of thumbnail sizes

Sam Wilson via Wikitech-l <[email protected]> Sun, 25 Jan 2026 13:02:33 +0800
Newsgroups gmane.science.linguistics.wikipedia.technical
Message-ID <[email protected]>
Looks great, thanks!

On 25/1/26 12:32, Travis Briggs wrote:
> Added an "FAQ" section to that article. How does it look now? 
> https://www.mediawiki.org/wiki/Common_thumbnail_sizes
>
> Cheers,
> -Travis
>
> On Fri, Jan 23, 2026 at 10:38 PM Sam Wilson via Wikitech-l 
> <[email protected]> wrote:
>
>     This is great, and I'm sure many 3rd party installs will be glad
>     of it too (to reduce their thumb storage requirements).
>
>     A couple of times lately I've had the "429 Use thumbnail steps
>     listed on https://w.wiki/GHai" message, and because I'm a bit slow
>     on the uptake I went looking for the steps to follow to get
>     thumbnails. Has anyone else been confused by this? If it's just
>     me, ignore this, but perhaps we could update the message to say
>     "Use the values of $wgThumbnailSteps listed on…" instead.
>
>
>     On 24/1/26 02:27, Amir Sarabadani via Wikitech-l wrote:
>>     Thumbnails shown on-wiki are already quantized to a set of
>>     standard sizes (if a non-standard size is requested, the
>>     next-larger standard size is used, and scaled to the requested
>>     size by the browser). We have recently extended the set of
>>     standard sizes, and are now moving to only allow standard sizes
>>     to be used. Regular editing and viewing will not be impacted by
>>     this change at all.
>>
>>     * What isn't changing?
>>
>>     Thumbnails served on wiki (via the "thumb" argument to File:, and
>>     via the Media API) will continue to behave as they do now - if
>>     you request a non-standard size, the next-larger standard size
>>     will be provided, and scaled in-browser if appropriate.
>>
>>     * What is changing?
>>
>>     Requests for non-standard thumbnail sizes using other methods
>>     (e.g. constructing an upload.wikimedia.org
>>     <http://upload.wikimedia.org> URL with a non-standard thumbnail
>>     size) will be blocked by our CDN. These are already being
>>     rate-limited for requests that we assess are not coming from a
>>     web-browser.
>>
>>     During this quarter, we will be broadening the scope of the
>>     existing rate-limiting and making it increasingly strict, with
>>     the aim being to refuse such requests entirely by the end of
>>     March 2026.
>>
>>     * Why are WMF doing this?
>>
>>     Historically, we have generated thumbnails of whatever size was
>>     requested; this has been a drain on our thumbnailing
>>     infrastructure and cost us in network bandwidth and storage
>>     volume. With the increasing prevalence of highly aggressive
>>     scrapers, this has become an intolerable burden on our network,
>>     infrastructure, and staff, who have spent a lot of time over the
>>     holiday period working hard to keep the wikis available for
>>     people to read in the face of automated abuse.
>>
>>     * What do I need to do?
>>
>>     Most likely, nothing: we have already tracked down some of the
>>     more widely-deployed sources of nonstandard thumbnail requests
>>     (e.g. Popups extension) and fixed them. If you own or operate
>>     something that requests thumbnails by constructing a thumbnail
>>     URI directly, then now is the time to either use the Media API
>>     instead or to make sure you only request standard thumbnail sizes.
>>
>>     * What are the standard thumbnail sizes?
>>
>>     They are: 20px, 40px, 60px, 120px, 250px, 330px, 500px, 960px,
>>     1280px, 1920px, 3840px
>>
>>     They are defined in config as $wgThumbnailSteps -
>>     https://gerrit.wikimedia.org/r/plugins/gitiles/operations/mediawiki-config/+/refs/heads/master/wmf-config/CommonSettings.php
>>
>>     And also documented on MetaWiki -
>>     https://www.mediawiki.org/wiki/Common_thumbnail_sizes
>>
>>     To help fix the existing instances, please see
>>     https://phabricator.wikimedia.org/T414805 for search-links, and
>>     examples of how to fix them.
>>
>>     Best
>>     --
>>     *Amir Sarabadani (he/him)*
>>     Staff Database Architect
>>     Wikimedia Foundation <https://wikimediafoundation.org/>
>>
>>     	
>>
>>
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