DeDot

Revision as of 05:49, 20 May 2020

Description

Spatial and temporal plugin to reduce cross-luminance (dot crawl) and cross-color (rainbows). The official name of this plugin is DeDot_YV12 and is based on DeDot v0.3 by thejam79.

The luma and the chroma are filtered completely independently from each other. It doesn't filter moving objects.

Requirements

• [x86] AviSynth+ or AviSynth 2.60
• [x64] AviSynth+
• Supported color formats: Y8, YV12, YV16, YV24

• Microsoft Visual C++ 2019 Redistributable Package (x86 / x64)

*** vc_redist.x86.exe is required for DeDot-x86

*** vc_redist.x64.exe is required for DeDot-x64

Syntax and Parameters

DeDot (clip, int "luma2d", int "lumaT", int "chromaT1", int "chromaT2")

clip   =

Input clip. It must have constant format and dimensions and it must be 8 bit Gray or YUV.

int  luma2d = 20

Spatial luma threshold. Must be between 0 and 510.

Lower values consider more pixels as cross-luminance.

If luma_2d=510, the luma is returned without any processing.

int  lumaT = 20

Tolerance for temporal variation in the luma channel (Y). Must be between 0 and 255.

Higher values consider more pixels as cross-luminance.

If luma_t=0, the luma is returned without any processing.

int  chromaT1 = 15

Tolerance for temporal variation in the chroma channels (U,V). Must be between 0 and 255.

Higher values consider more pixels as cross-color.

int  chromaT2 = 5

Temporal chroma threshold. Must be between 0 and 255.

Lower values consider more pixels as cross-color.

If chroma_t2=255, the chroma is returned without any processing.

Examples

DeDot with all default values:

MPEG2Source("DotCrawl.d2v")
DeDot(luma2d=20, lumaT=20, chromaT1=15, chromaT2=5) 

Reduce dot crawl only:

• Adjust luma2d and lumaT accordingly.

MPEG2Source("DotCrawl.d2v")
DeDot(luma2d=20, lumaT=20, chromaT1=0, chromaT2=255) 

Reduce rainbows only:

• Adjust chromaT1 and chromaT2 accordingly.

MPEG2Source("Rainbows.d2v")
DeDot(luma2d=510, lumaT=0, chromaT1=15, chromaT2=5) 

How it works

Written by tritical

I'll give a quick explanation of how the parameters are used in relation to pixel values (this is all taken simply from reading the source code).
Its operation is quite simple, which is why it is very fast and is able to be written completely in MMX.


For filtering luma (dot crawl) it uses luma2d and lumaT... Consider 'e' to be the current pixel and a,b,c,d,f,g,h,i to be its spatial neighbors in the current frame:

a	b	c
d	e	f
g	h	i

DeDot first uses the following two tests:

abs(b+h-2*e) > luma2d

abs(d+f-2*e) > luma2d

If either of those conditions is met it goes on and tests the following conditions else it drops out w/o doing any filtering on that luma pixel.
For the next tests consider pixel 'c' to be the pixel in the current frame and a,b,d,e to be its temporal neighbors in adjacent frames:

a

b

c

d

e

abs(c-a) <= lumaT

abs(c-e) <= lumaT

abs(b-d) <= lumaT

If all three of those conditions are met it decides that the pixel needs to be filtered and it either averages the current pixel 'c' with 'b' or 'd' based on whichever one is closer to the value of 'c'.


Chroma filtering (rainbow removal) works in the following way. First it tests the following conditions... Again assume 'c' is from the current frame and a,b,d,e are the temporal neighbors:

a

b

c

d

e

abs(c-a) <= chromaT1

abs(c-e) <= chromaT1

abs(b-d) <= chromaT1

abs(c-b) > chromaT2

abs(c-d) > chromaT2

If all five of those conditions are met then it does filtering on the pixel. For the filtering it either averages the current pixel 'c' with 'b' or 'd' based on whichever one is closer to the value of 'c'.

Hope that helps explain the parameters a little bit better.

Changelog

 2020/05/15 v1.1.0
     - Move project to GitHub

 2019/06/07 
     - Backport DeDot from VapourSynth port by Dubhater
     - Add Y8, YV16, YV24 and drop YUY2 support
     - x64 version
     - Compiled with Microsoft Visual Studio C++ 2017
     - Author: Asd

 v0.0.01:
     - Initial release

External Links

• Doom9 Forum - DeDot discussion and English translation by niiyan.
• Doom9 Forum - DeDot discussion and English translation by helix. In the last post, tritical explains how DeDot works.
• Doom9 Forum - DeDot discussion about correct usage, English translation, and some history of DeDot by niiyan.
• Scintilla's Guide - English documentation by Scintilla.
• GitHub - Source code repository.
• GitHub - Source code repository (VapourSynth version).

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