Alternative for the True Color Option - Format

I’m following a tutorial, the tutor is using Unity 5 but I’m using Unity 5.5. Under the Inspector component, Format, the tutor selects True color but in Unity 5.5 the true color option is not available. Is there any other alternative to it?

Under compression, set to none

Based on the screenshot, the compression is grayed out. I would also know what to do in a case like this, which selection should be used as an alternative?89932-tru.png