Does Unity Care is a texture is a power of 2?

This have been a topic of debate between my coworkers with no clear answer.

For optimization/performance purposes does UNITY care if a texture is a power of two or not. It seems that it re sizes the texture internally. My opinion is that it does not, but other people I work with think otherwise. It would be nice to get a final answer for this.

Thanks

It is possible to use other (non power
of two) texture sizes with Unity. Non
power of two texture sizes work best
when used on GUI Textures, however if
used on anything else they will be
converted to an uncompressed RGBA 32
bit format. That means they will take
up more video memory (compared to
PVRT(iOS)/DXT(Desktop) compressed
textures), will be slower to load and
slower to render (if you are on iOS
mode). In general you’ll use non power
of two sizes only for GUI purposes.

Non power of two texture assets can be
scaled up at import time using the Non
Power of 2 option in the advanced
texture type in the import settings.
Unity will scale texture contents as
requested, and in the game they will
behave just like any other texture, so
they can still be compressed and very
fast to load.

So in essence, yes, Unity does care as it will automatically assign properties to the texture unless you override it to do differently. When using a compressed format, you’ll see that all textures are scaled automatically to a square power of 2 texture size. With a compressed format, this is done automatically because compression rates typically will only work well with power of 2 sizes. If they are not, they will be practically double the size, which is why this is automatically done for you.

Also, compression and power of 2 sizes can be hardware dependent, as well as the algorithm used (such as PVRTC on iOS). Non Power of Two (NPOT) texture capability can vary, say from the PowerVR chipset in the iPhones to something else on an Android phone.

Power of 2 textures nowadays are typically requested by the Game Engine strictly for mip-mapping purposes. If the texture is not in the dimensions of power of 2, then processing for mip-mapping won’t be able to take place.