Thread:Talk:Requests for comment/Standardized thumbnails sizes/Browser scaling/reply (3)

@Brion: Your hi-res image serving has been very effective. But editors do notice blurriness and complain at VPT when they accidentally change their zoom on desktop browsers, so optimal rendering at 100% zoom on desktop browsers should continue to be a key requirement for the foreseeable future.

The proposal has the following drawbacks:


 * 1) Browser scaling of a server-scaled image will generally produce a worse result than a single scaling, unless the cache-scaled image is more than about 200% the display dimensions; but serving 200%+ images for browsers to downscale is unlikely to be acceptable to low-bandwidth users, so quality or speed would be sacrificed.
 * 2) Many images are used as icons, where precise pixel control is necessary.
 * 3) Serving images at higher-than-displayed resolutions would increase bandwidth.
 * 4) There is no evidence that the current flexibility is causing adverse results.
 * 5) Conversely, the proposal would still permit numerous different sizes to be cached for any uploaded image. So the thumbnail servers would remain just as vulnerable to DOS requests for rare-but-permitted large scalings of numerous different images.

Therefore served sizes should be identical to rendered size (as now) or at least the lesser of original size and 200% of the intended size (but only if low-bandwidth users do not object).

If DOS mitigation is an intended result, it requires a completely different approach. (Possibilities might be indentifying pathological request patterns; or serving unscaled images for uncached thumbnails that have not been generated within a set interval.)