# Plum ©2021 IFeelBloated, Plum Python Module for VapourSynth

License

LGPL v3.0

Description

Plum is a sharpening/blind deconvolution suite with certain advanced features like Non-Local error, Block Matching, etc..

Requirements

• NNEDI3
• KNLMeansCL
• BM3D
• FMTConv
• VCM
• MVTools (floating point ver)

Function List

• Super
• Basic
• Final

Formats

• Bit Depth: 32bits floating point
• Color Space: Gray, RGB, YUV4XXPS
• Scan Type: Progressive

Notes

• Only Y will be processed when the input is YUV, UV will be simply copied from the input
• RGB input will be converted to an opponent color space(YUV alike) and only luma will be processed
• NO scene change policy provided, take Wobbly and cut each scene out and process them individually
• QUALITY: cutting edge
• PERFORMANCE: close to abysmal

Details

Super

Optional, it helps improve the precision of sub-pixel motion estimation and compensation, use it and get a quality boost or don't and get a performance boost

Super(src, pel=4)

• src
  clip to be processed
• pel
  sub-pixel precision, could be 2 or 4, 2 = precision by half a pixel, 4 = precision by quarter a pixel.

Basic

The basic estimation performs sharpening with spatial self similarity to cancel out ringing, the sharpening kernel is not unsharpen masking, it's a blind deconvolution filter (assuming PSF is a circle).

workflow:

• do the blind deconvolution to enhance the overall sharpness.
• filter the result of deconvolution with supersampled Non-Local Errors, which shifts high frequency components from the deconvolved clip to the source clip without any new ringing/aliasing (could enhance the existing ringing/aliasing).
• clamp the result with a Local Errors unsharpen masking since most videos are not completely ringing-free, this makes sure the existing ringing won't be enhanced (at least won't be enhanced much).
• shrink the result down by 1 pixel
• repeat all steps above a few times
• do another Non-Local Errors filtering to remove all residual ringing. (ringing inherited from the source clip)
• apply a cutoff filter to restore low frequency components.

Basic(src, strength=3.20, a=32, h=[6.4, 64.0], radius=1, wn=0.48, scale=0.28, cutoff=24)

• strength
  controls the iterating process, repeat floor(strength) and ceil(strength) times and blend them according to the fractional part of the strength.
• a
  window size of the non-local error filtering.
• h
  h[0]: standard deviation of the non-local error filtering, default value is pretty balanced.
  h[1]: strength of the local errors filtering, greater value = more relaxed clamping.
• radius
  radius of the deconvolution filter
• wn, scale
  refer to VCFreq doc for more details.
• cutoff
  strength of the cutoff filter, ranges from 0 (no low frequency protection) to 100 (almost no filtering)

Final

The final estimation adjusts the basic estimation using temporal self similarity to cancel out noise and residual aliasing.

workflow:

• do a motion compensated temporal averaging to the difference between the basic estimation and the source clip, then apply the stabilized difference back to the source clip.
• clamp the result temporally with motion compensation.
• get the difference between the result and the source clip and amplify it non-linearly, then apply it back.
• apply a cutoff filter to restore low frequency components.

Final(src, super=[None, None], radius=6, pel=4, sad=400.0, flexibility=0.64, strength=3.20, constants=[1.49, 1.272, None], cutoff=12, freq_margin=20)

• super
  optional, clips generated by Plum.Super
• radius
  temporal radius, frames that fall in [current frame - radius, current frame + radius] will be referenced
• sad
  SAD threshold of the motion compensation, refer to MVTools doc for more details
• flexibility
  flexibility of the motion compensated temporal clamping, on a scale of [0.0, 1.0], greater value = more relaxed clamping
• strength
  general amplitude of the non-linear amplification function.
• constants
  parameters related to the non-linear amplification function
  constants[0]: modifier for the amplification function
  constants[1]: exponent for the amplification function
  constants[2]: suppression to the very small differences, default = strength + 0.1
• freq_margin
  frequency margin of the cutoff threshold, larger value = more delicate and less agressive sharpening

Demos

• A

  ref = Plum.Basic(clip, strength=6.4, cutoff=32)
  clip = Plum.Final([clip, ref], [Plum.Super(clip), Plum.Super(ref)], strength=1.8, freq_margin=12)

  

• B

  ref = Plum.Basic(clip)
  clip = Plum.Final([clip, ref], [Plum.Super(clip), Plum.Super(ref)], cutoff=8, freq_margin=12)

  

• C

  ref = Plum.Basic(clip)
  clip = Plum.Final([clip, ref], [Plum.Super(clip), Plum.Super(ref)])