digitalFAQ.com Forum - Script for cleaning right border stain on PAL VHS

I use a script for cleaning the green staining on the right edge that typically occurs when Hi8 tapes are digitized with Sony Handycams.

Today I have a VHS tape, which as far as I am aware is a master recording, on Fuji Super XG Pro 180 VHS Tape, PAL. I am 95% certain it is the original and did not come from Hi8. Anyway, it has green staining on the right border.

The script I normally use to clean the stain is causing magenta staining. Most noticeable on frames 430 to 440 in the attached clip. This is the script:-

Code:

U = UtoY() # separate U channel

V = VtoY() # separate V channel

V = Crop(V,0,0,-16,-0) #remove discoloured portion and black border

extra=FlipHorizontal(V).Crop(0,0,12,-0) # the last 12 pixels of the V channel reflected 

  ###ALTERNATIVELY stretch the last good pixels of chroma rather than reflecting, by changing the "extra" line to: 

#extra=Crop(V,342,0,2,-0).PointResize(12,V.height)

V=StackHorizontal(V,extra).AddBorders(0,0,4,0,$808080) # add the extra, pad to 720 with grey

YtoUV(U, V, last) # mix the separate U and V with the original Y

If I unhash and use the Alternative 'extra' it produces better results but the magenta staining is still apparent:-

Code:

U = UtoY() # separate U channel

V = VtoY() # separate V channel

V = Crop(V,0,0,-16,-0) #remove discoloured portion and black border

extra=Crop(V,342,0,2,-0).PointResize(12,V.height)

V=StackHorizontal(V,extra).AddBorders(0,0,4,0,$808080) # add the extra, pad to 720 with grey

YtoUV(U, V, last) # mix the separate U and V with the original Y

I have temporarily hashed out the Crop and Add Borders at the end of my full script (below) to show the staining more clearly.

I have never understood what this script is doing or how it works, but I would really like some advise on what values I can change. If I change a single number it creates an error so I am lost for what I can change in that script. A breakdown explanation of what the above script is doing would be very helpful.

My full script:-

Code:

function Levels_mod(clip c, int "input_low", float "gamma", int "input_high", int "output_low", int "output_high", bool "coring", bool "dither")

{

return c.Levels(default(input_low, 0),

\                default(gamma, 1.0),

\                default(input_high, 255),

\                default(output_low, 0),

\                default(output_high, 255),

\                default(coring, true),

\                default(dither, false))

}



function LevelsLumaOnly(clip c,

\                       int "input_low", float "gamma", int "input_high",

\                       int "output_low", int "output_high", bool "coring", bool "dither")

{

    return MergeChroma(c.Levels_mod(input_low=input_low, gamma=gamma, input_high=input_high,

    \                           output_low=output_low, output_high=output_high, coring=coring, dither=dither),

    \                  c)

}



# Classic Histogram and Levels Histogram

function ClassicAndLevelsHistogram(clip video)

{

  classic = video.TurnRight().Histogram().TurnLeft().crop(0,0,-0,256)

  levels = video.Histogram("levels").crop(video.width,0,-0,256)

  classic_and_levels = stackhorizontal(classic, levels) # stack classic and levels horizontally

  video2 = video.addborders(0,0,classic_and_levels.width-video.width,0) # add a black border to side of the video to match the width of "both"

  stackvertical(classic_and_levels, video2) # stack the analytics over the video

}







SetFilterMTMode("QTGMC", 2) 

AviSource("2022.04.25a - Lagarith Clip.avi", atrack=0)

AssumeTFF() 



### ----------REMOVE GREEN STAINING FROM THE RIGHT HAND EDGE

U = UtoY() # separate U channel

V = VtoY() # separate V channel

V = Crop(V,0,0,-16,-0) #remove discoloured portion and black border

extra=FlipHorizontal(V).Crop(0,0,12,-0) # the last 12 pixels of the V channel reflected 

  ###ALTERNATIVELY stretch the last good pixels of chroma rather than reflecting, by changing the "extra" line to: 

#extra=Crop(V,342,0,2,-0).PointResize(12,V.height)

V=StackHorizontal(V,extra).AddBorders(0,0,4,0,$808080) # add the extra, pad to 720 with grey

YtoUV(U, V, last) # mix the separate U and V with the original Y



### ----------ADJUST LEVELS  

#Levels(10, 1.0, 245, 16, 235, coring=false, dither=true) 

LevelsLumaOnly(5, 1.0, 240, 16, 235, coring=false, dither=true) 



### ----------ADJUST BRIGHTNESS, SATURATION AND HUE  

Tweak(hue=0.0, sat=1.05, bright=-8, cont=1.05, coring=False, sse=False, startHue=0, endHue=360, maxSat=150, minSat=0, interp=16)



###  ----------DEINTERLACE 

QTGMC(Preset="Slower", Edithreads=4) 



### ----------CROP TEMPORARILY FOR HISTOGRAM CHECK

#Crop(20,12,-20,-20) # HASH OUT THIS TEMPORARY CROP AFTER HISTOGRAM CHECK

#

### ----------CONVERT TO YV12 COLOURSPACE 

#ConvertToYV12(interlaced=false, matrix="PC.601")  

#

###  ----------ADJUST LUMA, RED, GREEN AND BLUE WHILST VIEWING HISTOGRAMS 

#ColorYUV(analyze=true)  

#ColorYUV(off_y=0, off_u=0, off_v=-5) 

#

#ClassicAndLevelsHistogram()





#Crop(12,0,-12,-12) 

#AddBorders(4,4,4,8) 



#ClassicAndLevelsHistogram() # (final check of levels with Crop and Add Borders) 



Prefetch(14)