Ubuntu – Do some icon themes have so many different sizes

iconslubuntuthemes

[12:24 PM] /usr/share/icons/hicolor $ ls
128x128  192x192  24x24    32x32  48x48    64x64  96x96             index.theme
16x16    22x22    256x256  36x36  512x512  72x72  icon-theme.cache  scalable
[12:24 PM] /usr/share/icons/hicolor $

By trial and error, I've figured out that 16×16, 22×22, 24×24, and 48×48 icons are used in Lubuntu 13.04. I may have seen icons corresponding to 64×64 and 128×128 being used but I'm not sure.
But what are all the other sizes for? Are they needed for very large screens?

Best Answer

The icons are used by multiple features in the unity system, and in all desktop environments, each choosing the size of the icon best suitable.

The sidebar, for example, uses a smaller icon than used by the application switcher (pressing alt+tab shows very large icons, it uses 256x256).

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