It seems the current favicon is missing other sizes resources in it, see:
https://github.com/audreyr/favicon-cheat-sheet

Following that logic a number of other resources need to be created for Piwik to look perfect in other devices (mobile, etc.).

I confirm. All icons in dashboard also need to be updated (folders, browsers, OS, etc.).

Footer icons in data tables are very unsharp as well

Same for Piwik update screen. The logo on top is not SVG and therefore blurry.

It is also not displaying a custom logo at the top of the update screen which is not related to this one though. (maybe it can be changed it one step)

Maybe it is as easy as replacing the 16x16 favicon by our 32x32 favicon http://piwik.org/favicon.png ?

Yep, that would be already better I reckon. Probably we need to specify the favicon in different sizes though in meta see eg https://github.com/audreyr/favicon-cheat-sheet not sure if needed though.

Many other icons and images are blurry too, shall we create separate issue for them?

Many other icons and images are blurry too, shall we create separate issue for them?

Yes, this is bigger project, but do-able (need to coordinate with designers)

done #9292

I reckon we need to favicon.png as ico @mattab