Preview a voronoi/magic/clouds/other texture? Usually, when I am using a Displace modifier on an object and want to use a texture for it, I can get a preview in the texture tab:



However, when I use the texture in the node editor as a mix shader fac input (as I have been doing recently), I cannot preview the texture in the texture tab.



How can I preview the texture in the node editor and change the contrast/brightness as I can with the Displace textures?

Thank you in advance.
You can't currently preview cycles textures independently in the texture tab, as far as I know, they belong to a completely different rendering system.

You can however get some kind of preview of the texture by previewing the material itself in the Materials tab of the Properties Window by expanding the preview panel and switching to a Flat preview object.