HistogramAdjust

Abstract
Author	V.C.Mohan
Version	25 Aug 2017
Download	modPlus.7z
Category	External filters
License	GPLv2
Discussion	HistogramAdjust plugin

Description

This function adjusts the histogram of a frame by either equalizing it or by matching with histogram of another image, or with given histogram table of values.

The function accepts RGB, YUY2 and Planar color formats. Clip to be processed and to be used for matching need not have identical color formats and dimensions. For example processing clip can be YV12 , 720 X 480 pixels while matching clip is YUY2, 256 X 16 pixels. However their bit depths must be same.

If matching with given table values, then matching clip need not be specified. The second parameter is a table of integer pairs.Each pair consists of Luma ( intensity)value and the second number is %population (type = 3) or %cummulative population (type = 4) at this value.The table is normalized by the function and so approximate values are OK. Not more than 25 pairs can be specified. It will be possible to input by table any desired histogram shape. The plugin linearly interpolates and extrapolates to construct a full normalized histogram from these values. In case of RGB input the selected color histogram is tweaked ( in case all 3 color components of RGB input are to be tweaked the function may be invoked in the script 3 times). For other formats only Y value histogram is tweaked.

Requirements

• AviSynth+ r2347 or greater
• source video: progressive
• color formats -->Supported color formats: YUY2, YV12,YV16, YV24, YV411, Y8

Syntax and Parameters

HistogramAdjust(clip, int array "", string "type", bool "table ",clip mclip",int mf",bool window",int w",int h",int limit")

clip   =

Input clip.

  int array =

table of luma and population pairs in case table is true .

type  string = "equal"

"equal" or "match"

table  bool = false

Whether table of values are specified for matching Histogram.

mclip  clip = clip

Clip with which input clip histogram is to be matched .

mf  int = 0

frame number of mclip with which clip histogram is to be matched .

window  bool = false

Whether windowed equalization is to be done .

w  int = frame width/4

If window is true, width of window (odd number) to be used.

h  int = frame height/4

If window is true, height of window (odd number) to be used.

limit  int = 100

percentage of deviation from original value of luma to be allowed .

Examples

Usage examples:-

TweakHist()

TweakHist(c, type=2, mclip=mm, mf=26)

TweakHist(c, 15, 2, 30, 12, 50, 33, 90, 12, 150, 35, 200, 10, type=3, limit=50)

TweakHist(20, 1, 150, 100, 255, 110, type=4, limit=70)

RGB input. Repeated for each color

TweakHist(limit = 70, rgb = 0)

TweakHist(limit = 70, rgb = 1)

TweakHist(limit = 50, rgb = 2)

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