The indicates that the Levels filter should be compatible with the one from VirtualDub, but I'm not getting the same results. I made the following script: Code:

AFAIK the conversion RGB->YUY2 itself implements a level transform for the luminance from 0...255 to 16...240

235 max for Y, 240 for U and V (just to be picky).

Okay, therefore what should I be doing to go reliably from VirtualDub values to Avisynth ones in YUY2?

Am I to assume, then, that if I want to use VirtualDub's Levels dialog to determine settings to use in Avisynth, I'm restricted to using RGB? Therefore, in my script, I'd need to convert to RGB, apply Levels, and then convert back to YUY2? Ick...

Maybe this one could help (colorYUY2 is an external plugin)? ColorYUY2(Levels="TV->PC") I think that will enable you to get same basic levels than using RGB.

No, this actually DOES a conversion. What stickboy wants is a conversion of the settings only.

I suppose this must just be a stupid question. What does everyone else do? Do you all: A. not use Levels B. use the guess-and-check method for finding appropriate values C. convert to RGB before using Levels (and similarly using RGB mode in the VirtualDub Levels dialog) D. use something other than VirtualDub's Levels dialog for generating a histogram and for dynamic previews E. ...? (Obviously I don't have a solid grasp of how luminance works; could anyone point me to a good guide?)

Luminance 

There are two histogram functions available in Avisynth: Histogram() bulit-in, Y-channel only Videoscope() - more options Does anybody (meaning neuron2 :) ) know how to get the "intensity" function from the Hue/Saturation/Intensity Filter for VirtualDub in AviSynth??