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Comment by dorianj | Hacker News Reader

This is needlessly complex. I really don't see pixel ratios of anything more than 2x being useful. Having two versions of assets is painful enough.

The apple convention, of having images with "@2x" appended, works quite well. The server could look for a http header indicating DPI and serve accordingly. This gives the developer to provide either one single HiDPI that's served to all clients, or separate files for HiDPI and normal resolution.

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It is short-sighted to assume that 2x will be the limit of high-resolution images. If we're making browser developers add support for this, we might as well have it be at least somewhat future-proof.

Meaning of "1x" has changed from 72dpi to 100-130dpi over time.

It's not unreasonable to assume that same will happen with "2x" as screen densities gradually improve, and over time it will shift from 220dpi to 300dpi-400dpi (for desktop viewing distances).

Density doesn't need to improve indefinitely, it just needs to cross the "retina" threshold (which arguably 2x does already).

I mistakenly included a great deal of peripheral detail in the first draft. It's not as complex as all that. It is sufficient to provide only 2 versions of each asset: the 1:1 default and a higher-res version, whether it's 2x or 15MP.

You mention an HTTP header indicating DPI. Sending device pixel ratio is already a major part of the HAIR proposal; see Example 2. If that's all that got added to browsers and servers, it would eliminate most of the app-level solutions out there.

There are already ratios of 1.5, 1.33 and 2.25 in the wild.

See Android

Wait, are you saying there's a version of Android somewhere that ships with a web browser which actually specifies its device pixel ratio as a non-integer? I am dubious, since I assume that would force rough anti-aliasing on everything and look like crap.

Some power users with 2880x1800 MBPs are using them at 1920x1200. Sounds crazy but I looked at it and found it almost bearable.

The device pixel ratio is simply the conversion ratio between device pixels and css pixels. It is on the device makers to determine how to interpolate image data into CSS pixels in the browser. There are many devices that have non-integer based DPRs. From what I recall, earlier devices even have DPRs of 0.75

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