AviSynth Levels - "operate in luma instead of RGB"?

[tat2jr]

I'm VERY new to using AviSynth. I want to use the levels settings I use in VirtualDubMod. I always UNCHECK "operate in luma instead of RGB" in Vdub. How do I specify that in AviSynth?

So far I got (no change):
Levels(0, 1, 255, 0, 255,?)

Not sure what my clip value should be to match vdub, and I have no idea how to duplicate the unchecking of "operate in luma instead of RGB" in vdub.

Thanks in advance.

[jagabo]

From the AVISynth docs:

This is one of those filters for which it would really be nice to have a GUI. Since I can't offer a GUI (at least not in AviSynth's current form), I decided I could at least make this filter compatible with VirtualDub's when the clip is RGB. In that case you should be able to take the numbers from VirtualDub's Levels dialog and pass them as parameters to the Levels filter and get the same results.

The results are pretty close: