Questions on YUV to RGB conversion & using Color Tools histograms
 

I think I read somewhere where VirtualDub does a good job of converting to RGB before applying filters. Why do many scripts convert from YUV to RGB in AviSynth before using VirtualDub?

I've been working on various videos using VirtualDub's filters. I think I've been misusing the Color Tools histograms. I assumed that I needed to keep levels within the 16 to 235 range. But, in rereading some of the material here, I read that the conversion from YUV to RGB expands the YUV 16 to 235 levels to RGB 0 to 255. Therefore, I need to work in the full 0 to 255 range while in VirtualDub--true?

Thanks,
Steve