View source for Ylevels

{{FilterCat|External_filters|Adjustment_filters|Levels_and_Chroma_filters}}
{{Filter
|Did&eacute;e
|1.0
|
* [[Media:YLevels.avsi|MaskTools version]]
* [[Media:YLevels_mt.avsi|MaskTools2 version]]
|Levels and Chroma filters
|
* [[YV12]]
|?
}}

== Required Plugins ==

* Original version: [[MaskTools]]
* MaskTools2-updated version: [[MaskTools2]]

== Description ==

YLevels is a set of filters to replace the internal AviSynth [[Levels]] filter using the mask manipulation facilities provided by [[MaskTools]].  

It lets you choose different gamma curves, e.g. to boost dark areas without washing out bright ones. Unlike Levels it does not clip values outside the given range; it also uses named/optional parameters, negating the need for wrappers.  

== Filters ==

All functions are called the same way as AviSynth's [[Levels]] command, except for the <tt>coring</tt> parameter. Coring is not available with the Ylevels() functions. They will always work on the full [0,255] value range.

* {{FuncDef|Ylevels}} 
: A simple replacement for Avisynth's internal levels() command, with a few neat differences:
:* processes only luma. This makes it faster and allows better preservation of color saturation.
:* no clipping: Ylevels(40,1.0,220, 40, 220) will not clip the output to [40,220] as Levels() does. Values below 40 / above 220 will be scaled accordingly to the correct vales. This means, one can use any values for IN_LOW, IN_HIGH as "control points" without getting the input clipped at those values.

*{{FuncDef|YlevelsG}}, {{FuncDef|YlevelsS}}
: Apply the given levels conversion by 100% @ Luma==0, by 0% @ Luma=255, and accordingly in-between. YlevelsG() does a linear sweep (G = Gradient), while YlevelsS() does a sine sweep (S = Sine). Try those with gamma values 1.5 ~ 4.0.
: ''Note:'' YlevelsG (not YlevelsS) does "inverse" scaling for gamma values < 1.0, but that's not that great. It's just for completeness.

* {{FuncDef|YlevelsC}}
: For this one, 2.0 < gamma < 16.0 is reasonable.

== Links ==
* [http://forum.doom9.org/showthread.php?t=79898 YLevels thread in doom9]
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