Understanding Levels in Firesledge's Dither

[j7n]

I am using Dither 1.19.0 and AviSynth 2.5.8 to downscale, deband and add dither noise to videos. I got Dither from here a long time ago, and have been happy with the results.

However, I am still using basic Levels() from AviSynth, even though I realize increased precision would be needed for this task more than anywhere else. I find the level adjustment in Dither difficult to understand.

The documentation mentions working with curves and converting sample range between TV and PC. So the plug-in is most certainly capable of basic level adjustment.

The docs mention "lut", which I understand stands for look-up table, as well as "reverse polish notation". These terms appear rather intimidating.

I'd like to insert level adjustment, while the picture is still in 16-bits, and avoid installing any new plug-ins to prevent conflicts with my existing stuff.

Could someone please give me a few examples of shifting the histogram up or down, or multiplying it to stretch it? No linear light, or gamma, or anything like that, yet.