Limiter

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m (one more touch-up)
m ('show)
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! style="text-align:left;width:12em;"|{{FuncArg|show}}="luma"
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! style="text-align:left;width:12em;"| {{FuncArg|show}}="luma"
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! style="text-align:left;width:12em;"|{{FuncArg|show}}="luma_grey"
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! style="text-align:left;width:12em;"| {{FuncArg|show}}="luma_grey"
 
|-  
 
|-  
 
| ''Y''j < {{FuncArg|min_luma}}
 
| ''Y''j < {{FuncArg|min_luma}}
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| red (pj)
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| &nbsp;{{BoldColor|#FF0000|120|&diams;}} red (pj)
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| red (pj)
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| &nbsp;{{BoldColor|#FF0000|120|&diams;}} red (pj)
 
|-  
 
|-  
 
| ''Y''j > {{FuncArg|max_luma}}
 
| ''Y''j > {{FuncArg|max_luma}}
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| green (pj)
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| &nbsp;{{BoldColor|#00FF00|120|&diams;}} green (pj)
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| green (pj)
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| &nbsp;{{BoldColor|#00FF00|120|&diams;}} green (pj)
 
|-  
 
|-  
 
| ''Y''j < {{FuncArg|min_luma}}&nbsp;and ''Y''k&nbsp;>&nbsp;{{FuncArg|max_luma}}
 
| ''Y''j < {{FuncArg|min_luma}}&nbsp;and ''Y''k&nbsp;>&nbsp;{{FuncArg|max_luma}}
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| yellow (pj and pk)
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| &nbsp;{{BoldColor|#FFFF00|120|&diams;}} yellow (pj and pk)
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| puke (pj), olive (pk)
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| &nbsp;{{BoldColor|#555501|120|&diams;}}&nbsp;puke&nbsp;(pj) {{BoldColor|#A0A04A|120|&diams;}}&nbsp;olive&nbsp;(pk)
 
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! style="text-align:left;"|{{FuncArg|show}}="chroma"
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! style="text-align:left;"|&nbsp;{{FuncArg|show}}="chroma"
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! style="text-align:left;"|{{FuncArg|show}}="chroma_grey"
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! style="text-align:left;"|&nbsp;{{FuncArg|show}}="chroma_grey"
 
|-  
 
|-  
 
| ''U'' < {{FuncArg|min_chroma}}
 
| ''U'' < {{FuncArg|min_chroma}}
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| yellow
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| &nbsp;{{BoldColor|#FFFF00|120|&diams;}} yellow
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| yellow
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| &nbsp;{{BoldColor|#FFFF00|120|&diams;}} yellow
 
|-  
 
|-  
 
| ''U'' > {{FuncArg|max_chroma}}
 
| ''U'' > {{FuncArg|max_chroma}}
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| yellow
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| &nbsp;{{BoldColor|#FFFF00|120|&diams;}} yellow
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| blue
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| &nbsp;{{BoldColor|#0000FF|120|&diams;}} blue
 
|-  
 
|-  
 
| ''V'' < {{FuncArg|min_chroma}}
 
| ''V'' < {{FuncArg|min_chroma}}
−
| yellow
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| &nbsp;{{BoldColor|#FFFF00|120|&diams;}} yellow
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| cyan
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| &nbsp;{{BoldColor|#00FFFF|120|&diams;}} cyan
 
|-  
 
|-  
 
| ''V'' > {{FuncArg|max_chroma}}
 
| ''V'' > {{FuncArg|max_chroma}}
−
| yellow
+
| &nbsp;{{BoldColor|#FFFF00|120|&diams;}} yellow
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| red
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| &nbsp;{{BoldColor|#FF0000|120|&diams;}} red
 
|-  
 
|-  
 
| ''U'' < {{FuncArg|min_chroma}}&nbsp;and ''V''&nbsp;<&nbsp;{{FuncArg|min_chroma}}
 
| ''U'' < {{FuncArg|min_chroma}}&nbsp;and ''V''&nbsp;<&nbsp;{{FuncArg|min_chroma}}
−
| yellow
+
| &nbsp;{{BoldColor|#FFFF00|120|&diams;}} yellow
−
| green
+
| &nbsp;{{BoldColor|#00FF00|120|&diams;}} green
 
|-  
 
|-  
 
| ''U'' > {{FuncArg|max_chroma}}&nbsp;and ''V''&nbsp;<&nbsp;{{FuncArg|min_chroma}}
 
| ''U'' > {{FuncArg|max_chroma}}&nbsp;and ''V''&nbsp;<&nbsp;{{FuncArg|min_chroma}}
−
| yellow
+
| &nbsp;{{BoldColor|#FFFF00|120|&diams;}} yellow
−
| teal
+
| &nbsp;{{BoldColor|#008080|120|&diams;}} teal
 
|-  
 
|-  
 
| ''U'' < {{FuncArg|min_chroma}}&nbsp;and ''V''&nbsp;>&nbsp;{{FuncArg|max_chroma}}
 
| ''U'' < {{FuncArg|min_chroma}}&nbsp;and ''V''&nbsp;>&nbsp;{{FuncArg|max_chroma}}
−
| yellow
+
| &nbsp;{{BoldColor|#FFFF00|120|&diams;}} yellow
−
| orange
+
| &nbsp;{{BoldColor|#FFA500|120|&diams;}} orange
 
|-  
 
|-  
 
| ''U'' > {{FuncArg|max_chroma}}&nbsp;and ''V''&nbsp;>&nbsp;{{FuncArg|max_chroma}}
 
| ''U'' > {{FuncArg|max_chroma}}&nbsp;and ''V''&nbsp;>&nbsp;{{FuncArg|max_chroma}}
−
| yellow
+
| &nbsp;{{BoldColor|#FFFF00|120|&diams;}} yellow
−
| magenta
+
| &nbsp;{{BoldColor|#FF00FF|120|&diams;}} magenta
 
|}
 
|}
  

Revision as of 17:14, 23 January 2016

The standard known as Rec.601 or CCIR-601 (Studio Encoding Parameters of Digital Television...) defines standard quantization levels: for luminance, black is 16 and peak white is 235. This is the normal luminance range. For chrominance, the range is 16 to 240, or 128±112. "The signal may occasionally excurse beyond" these ranges according to Rec.601.BT.601-7 (Annex 1, Table 3)

Luminance or chrominance values outside their ranges are known to cause problems with some TV sets, so Limiter was created to clip them (or clamp them - both terms are used) to the ranges [min_luma, max_luma] and [min_chroma, max_chroma], which you may specify, but by default are the Rec.601 values listed above.

Limiter can also colorize out-of-range pixels (with show) to warn of a potential problem. See the example images below. Naturally, this option should not be enabled for final output.

Contents


Syntax and Parameters

Limiter(clip clip [, int min_luma, int max_luma, int min_chroma, int max_chroma, string show ] )

clip  clip = (required)
Source clip. YUV only.
int  min_luma = 16
Y (luma) lower clamping limit.
int  max_luma = 235
Y (luma) upper clamping limit.
int  min_chroma = 16
U & V (chroma) lower clamping limit.
int  max_chroma = 240
U & V (chroma) upper clamping limit.
string  show = (empty)
Colorizes the pixels outside the specified [min_X, max_X] range.
If set, show must take one of the following values:
show Effect
"luma" colorizes out of bound luma
"luma_grey" colorizes out of bound luma, and makes the remaining pixels grey
"chroma" colorizes out of bound chroma
"chroma_grey" colorizes out of bound chroma, and makes the remaining pixels grey
The colorizing is done as follows:
  • YUY2: j,k=1,2 (chroma shared between two horizontal pixels p1 and p2: Y1UY2V)
  • YV24: j,k=1 (no chroma shared)
  • YV12: j,k=11,12,21,22 (chroma shared between 2x2 pixels Y11UY12V: Y21UY22V)
Pixel Condition Colorization
 show="luma"  show="luma_grey"
Yj < min_luma  ♦ red (pj)  ♦ red (pj)
Yj > max_luma  ♦ green (pj)  ♦ green (pj)
Yj < min_luma and Yk > max_luma  ♦ yellow (pj and pk)  ♦ puke (pj) ♦ olive (pk)
 show="chroma"  show="chroma_grey"
U < min_chroma  ♦ yellow  ♦ yellow
U > max_chroma  ♦ yellow  ♦ blue
V < min_chroma  ♦ yellow  ♦ cyan
V > max_chroma  ♦ yellow  ♦ red
U < min_chroma and V < min_chroma  ♦ yellow  ♦ green
U > max_chroma and V < min_chroma  ♦ yellow  ♦ teal
U < min_chroma and V > max_chroma  ♦ yellow  ♦ orange
U > max_chroma and V > max_chroma  ♦ yellow  ♦ magenta


Examples 

# 1. Original image
FFmpegSource2("sintel.mp4")
Trim(4685, 4685)
ColorYUV(analyze=true)
Limit Ex01.jpg 
# 2. Exaggerated luma and chroma range
[...]
Levels(16, 1.0, 255-16, 0, 255, coring=false)
Tweak(sat=2.0, coring=false)
ColorYUV(analyze=true)
Limit Ex02.jpg 
# 3. Limiter("luma")
[...]
Limiter(16, 235, 16, 240, "luma")
ColorYUV(analyze=true)
Limit Ex03.jpg 
# 4. Limiter("luma_grey")
[...]
Limiter(16, 235, 16, 240, "luma_grey")
ColorYUV(analyze=true)
Limit Ex04.jpg 
# 5. Limiter("chroma")
[...]
Limiter(16, 235, 16, 240, "chroma")
ColorYUV(analyze=true)
Limit Ex05.jpg 
# 6. Limiter("chroma_grey")
[...]
Limiter(16, 235, 16, 240, "chroma_grey")
ColorYUV(analyze=true)
Limit Ex06.jpg

Changes

v2.60 Added support for YV24.
v2.56 Added show to show out of bound luma/chroma.
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