Levels - Revision history

Reel.Deal: add link to avs+ documentation

2022-09-17T07:35:04Z

add link to avs+ documentation

Reel.Deal: /* Syntax and Parameters */ fix dead link

2022-02-22T00:08:22Z

‎Syntax and Parameters: fix dead link

Raffriff42: typo

2018-09-14T03:42:44Z

typo

Raffriff42: tweak table

2018-01-15T15:51:56Z

tweak table

Raffriff42: rephrase & add "bit depth equivalent color value" table

2018-01-13T03:11:30Z

rephrase & add "bit depth equivalent color value" table

Raffriff42: AVS+ arguments are float as of r2580

2018-01-12T23:06:37Z

AVS+ arguments are float as of r2580

Raffriff42: coring note

2017-12-09T01:04:31Z

coring note

Raffriff42: note AVS+ differences

2017-04-28T20:46:34Z

note AVS+ differences

Raffriff42: formatting

2016-02-28T09:14:19Z

formatting

Raffriff42: format ''coring'', remove redundant example #5

2016-01-19T11:54:40Z

format ''coring'', remove redundant example #5

@@ Line 1: / Line 1: @@
 <div style="max-width:62em" >
 Adjusts brightness, contrast, and gamma. This is done using the following ''transfer function'':
 :''output'' = ( (''input'' - {{FuncArg|input_low}}) / ({{FuncArg|input_high}} - {{FuncArg|input_low}}) )<sup>(1 / {{FuncArg|gamma}})</sup> * ({{FuncArg|output_high}} - {{FuncArg|output_low}}) + {{FuncArg|output_low}}

@@ Line 102: / Line 102: @@
 ::{{FuncArg|coring}} was created for VirtualDub compatibility, and it remains true by default for compatibility with older scripts.
-::In the opinion of some, you should [http://forum.doom9.org/showthread.php?p=1722885#post1722885 always use ''coring=false''] if you are working directly with luma values (whether or not your input is 16{{D}}-235{{D}}).
+::In the opinion of some, you should [https://web.archive.org/web/20160825211112/http://forum.doom9.org/showthread.php?p=1722885#post1722885 always use ''coring=false''] if you are working directly with luma values (whether or not your input is 16{{D}}-235{{D}}).
 ::'''Note''' TV-range video ''can'' be correctly processed with {{FuncArg|coring}}=false; for example,
@@ Line 113: / Line 113: @@
 :{{Par2|dither|bool|false}}
 ::When ''true'', [[ordered dithering]] is applied to combat [http://en.wikipedia.org/wiki/Colour_banding banding]. Default is ''false''.
 ==== Examples ====

@@ Line 37: / Line 37: @@
 |style="text-align:right"|256
 |style="text-align:right"|2048
-|style="text-align:right"|3670
+|style="text-align:right"|3760
 |style="text-align:right"|4080
 |-

@@ Line 56: / Line 56: @@
 !32
 |style="text-align:right"|0.0
-|style="text-align:right"|0.0625
+|style="text-align:right"|<sup>16</sup>/<sub>256</sub>
-|style="text-align:right"|0.5000
+|style="text-align:right"|<sup>128</sup>/<sub>256</sub>
-|style="text-align:right"|0.9179
+|style="text-align:right"|<sup>235</sup>/<sub>256</sub>
-|style="text-align:right"|0.9961
+|style="text-align:right"|<sup>255</sup>/<sub>256</sub>
 |}

@@ Line 12: / Line 12: @@
 When processing data in [[YUV]] mode, '''Levels''' only gamma-corrects the luma information, not the chroma. Gamma correction is really an RGB concept, and is only approximated here in YUV. If ''{{FuncArg|gamma}}=1.0'' (unity), the filter should have the same effect in both RGB and YUV modes. For adjusting brightness or contrast in YUV mode, it ''may'' be better (depending on the effect you are looking for) to use [[Tweak]] or [[ColorYUV]], because '''Levels''' changes the chroma of the clip.
-{{AvsPluscon}} all parameters except {{FuncArg|gamma}} are ''non''-[[Autoscale_parameter|autoscaling]] &ndash; they must be scaled to the target bit depth.
+Note in {{AvsPluscon}}, the parameters {{FuncArg|input_low}}, {{FuncArg|input_high}}, {{FuncArg|output_low}} and {{FuncArg|output_high}}
 ==== Syntax and Parameters ====
 {{FuncDef|Levels(clip ''input'', <br>
-&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; int ''input_low'', float ''gamma'', int ''input_high'', <br>
+&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; int ''input_low'', float ''gamma'', int ''input_high'', int ''output_low'', int ''output_high''<br>
-&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; int ''output_low'', int ''output_high''<br>
+&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; [, bool ''coring'' , bool ''dither'' ] )}}<br>
-&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; [, bool ''coring'' , bool ''dither'' ] )}}
+{{FuncDef|Levels(clip ''input'', <br>
 :{{Par2|clip|clip|(required)}}
 ::Source video.
-:{{Par2|input_low|int*|(required)}}
+:{{Par2|input_low|int/float*|(required)}}
 ::Input values at {{FuncArg|input_low}} or lower are treated as ''black'', and lighter colors are darkened proportionally.
 ::Therefore raising {{FuncArg|input_low}} darkens the output.
-:: <big>*</big> {{AvsPluscon}} only &ndash; all arguments marked ''int*'' are floating point (from version r2580)
+:: <big>*</big> = <tt>int</tt> in AviSynth, <tt>float</tt> in AviSynth+
 :{{Par2|gamma|float|(required)}}
@@ Line 33: / Line 83: @@
 ::Higher {{FuncArg|gamma}} brightens the output; lower {{FuncArg|gamma}} darkens the output.
-:{{Par2|input_high|int*|(required)}}
+:{{Par2|input_high|int/float|(required)}}
 ::Input values at {{FuncArg|input_high}} or higher are treated as ''white'', and darker colors are brightened proportionally.
 ::Therefore lowering {{FuncArg|input_high}} brightens the output.
-:{{Par2|output_low|int*|(required)}}
+:{{Par2|output_low|int/float|(required)}}
 ::Dark values brighten to gray as {{FuncArg|output_low}} becomes larger.
-:{{Par2|output_high|int*|(required)}}
+:{{Par2|output_high|int/float|(required)}}
 ::Light values darken to gray as {{FuncArg|output_high}} becomes smaller.

@@ Line 5: / Line 5: @@
 *{{FuncArg|input_low}} and {{FuncArg|input_high}} determine what ''input'' pixel values are treated as pure black and pure white.
 *{{FuncArg|output_low}} and {{FuncArg|output_high}} determine what ''output'' values are treated as pure black and pure white.
 *{{FuncArg|gamma}} controls the degree of non-linearity in the conversion.
-This is one of those filters for which it would really be nice to have a GUI. Since we can't offer a GUI (though [http://forum.doom9.org/showthread.php?t=153248 AvsP] does), we at least make this filter '''compatible''' with [[VirtualDub|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. Unlike VirtualDub's filter however, the input and output parameters can be larger than 255.
+This is one of those filters for which it would really be nice to have a GUI. Since we can't offer a GUI (though [http://forum.doom9.org/showthread.php?t=153248 AvsP] does), we at least make this filter '''compatible''' with [[VirtualDub|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. Unlike VirtualDub's filter however, the input and output parameters can be larger than 255{{D}}.
 When processing data in [[YUV]] mode, '''Levels''' only gamma-corrects the luma information, not the chroma. Gamma correction is really an RGB concept, and is only approximated here in YUV. If ''{{FuncArg|gamma}}=1.0'' (unity), the filter should have the same effect in both RGB and YUV modes. For adjusting brightness or contrast in YUV mode, it ''may'' be better (depending on the effect you are looking for) to use [[Tweak]] or [[ColorYUV]], because '''Levels''' changes the chroma of the clip.
@@ Line 42: / Line 44: @@
 :{{Par2|coring|bool|true}}
 ::When ''true'' (the default),
-::#input luma is ''clamped'' to the range 16-235 and the chroma to 16-240;
+::#input luma is ''clamped'' to the range 16{{D}}-235{{D}} and the chroma to 16{{D}}-240{{D}};
-::#this clamped input is ''scaled'' from 16-235 to 0-255,
+::#this clamped input is ''scaled'' from 16{{D}}-235{{D}} to 0{{D}}-255{{D}},
 ::#the conversion takes place according to the transfer function above, and then
-::#output is scaled back to 16-235.
+::#output is scaled back to 16{{D}}-235{{D}}.
 ::When ''false'', the conversion takes place according to the transfer function, without any scaling.
 ::{{FuncArg|coring}} was created for VirtualDub compatibility, and it remains true by default for compatibility with older scripts.
-::In the opinion of some, you should [http://forum.doom9.org/showthread.php?p=1722885#post1722885 always use ''coring=false''] if you are working directly with luma values (whether or not your input is 16-235).
+::In the opinion of some, you should [http://forum.doom9.org/showthread.php?p=1722885#post1722885 always use ''coring=false''] if you are working directly with luma values (whether or not your input is 16{{D}}-235{{D}}).
 :{{Par2|dither|bool|false}}
@@ Line 62: / Line 64: @@
 <div {{BoxWidthIndent|64|2}} >
-  # the input is scaled from [16,235] to [0,255], the conversion [0,255]->[16,235] takes place
+  # the input is scaled from [16,235] to [0,255],
- # (accordingly to the formula), and the output is scaled back from [0,255] to [16,235]
+ # the conversion [0,255]->[16,235] takes place (according to the formula),
   # (for example: the luma values in [0,16] are all converted to 30)
   Levels(0, 1, 255, 16, 235)

@@ Line 39: / Line 39: @@
 ::Light values darken to gray as {{FuncArg|output_high}} becomes smaller.
-:{{Par2|coring|bool|false}}
+:{{Par2|coring|bool|true}}
-::When ''true'' (the default), input luma is ''clamped'' to [16,235] and the chroma to [16,240]; this clamped input is scaled from [16,235] to [0,255], the conversion takes place according to the transfer function above, and then output is scaled back from [0,255] to [16,235]. When ''false'', the conversion takes place according to the transfer function, without any scaling.
+::When ''true'' (the default),
-::{{FuncArg|coring}} was created for VirtualDub compatibility, and it remains true by default for compatibility with older scripts. In the opinion of some, you should [http://forum.doom9.org/showthread.php?p=1722885#post1722885 always use ''coring=false''] if you are working directly with luma values (whether or not your input is [16,235]).
+::{{FuncArg|coring}} was created for VirtualDub compatibility, and it remains true by default for compatibility with older scripts. In the opinion of some, you should [http://forum.doom9.org/showthread.php?p=1722885#post1722885 always use ''coring=false''] if you are working directly with luma values (whether or not your input is 16-235).
 :{{Par2|dither|bool|false}}
@@ Line 71: / Line 76: @@
   # example: luma of 16 is converted to 235
   Levels(0, 1, 255, 255, 0)
 </div>
@@ Line 98: / Line 98: @@
 <div {{BoxWidthIndent|64|2}} >
-  # apply fading on gamma corrected source (same holds for resizing and smoothing else well)
+  # apply fading on gamma corrected source (same holds for resizing and smoothing)
   clip = ...
   gamma = 2.2