[HELP] $100 seeking paid filter to remove purple fringing in old videos

[Selur]

Here's a quick fix:

• Start Hybrid
  
• load source
  
• enable "Filtering->Vapoursynth->Custom->Insert before DeCross" and enter:
  
  # create edgemask edges = core.std.Prewitt(clip.std.ShufflePlanes(0, vs.GRAY)) bits = clip.format.bits_per_sample thr = 32 << (bits - 8) # scale threshold to bitdepth mask = core.std.Binarize(edges, threshold=thr) # increase width of mask, by using higher integer values, depending on source and resolution increase = 0 for _ in range(increase): mask = core.std.Maximum(mask) # optional: soften mask edges mask = core.std.BoxBlur(mask, hradius=1, vradius=1) # create desaturated version mid = 1 << (bits - 1) mult = 0.5 # 0.0 = grayscale chroma, 1.0 = unchanged desat = core.std.Expr( [clip], expr=[ "", # keep luma unchanged f"x {mid} - {mult} * {mid} +", f"x {mid} - {mult} * {mid} +" ] ) # merge original with desaturated version around edges clip = core.std.MaskedMerge(clip, desat, mask)

To see what happens and tweaking the values depending on your source:

• enable "Filtering->Vapoursynth->Misc->Preview->Split Compare View" and set "FilterView mode" to "orginal|filtered|diff"
  
• enabled "Filtering->Compare view" (lower right corner)
  
• enabled "Filtering->Synth auto refresh" (lower right corner)
  
• open Vapoursynth Preview (lower right corner)
  

then adjust the parameters, i.e. thr, increase, mult, if your source differs from the sample.

The filtering should be fast, on any machine.
No filters used that do no come with Vapoursynth itself, so any tool which allows you to add custom Vapoursynth code should work fine.
(+ works on Linux, Mac, Windows)
Side note: if processing speed is an issue, external filters can replace the used filters:

• core.std.Prewitt => core.edgemasks.Prewitt
  
• core.std.BoxBlur => core.vszip.BoxBlur
  
• core.std.Expr => core.akarin.Expr
  

Cu Selur