# MipSmooth

## Abstract

author: Klaus Post (Sh0dan)
version: 1.11
download: http://cultact-server.novi.dk/kpo/avisynth/mipsmooth.html
category: Spatio-Temporal Smoothers
requirements:

- YV12 & YUY2 & RGB Colorspace
- ISSE support
- width divisible by 4 for YV12 and by 8 for YUY2

## Description

This is the MipSmoother - a reinvention of SmoothHiQ and Convolution3D. MipSmooth was made to enable smoothing of larger pixel areas than 3x3(x3), to remove blocks and smoothing out low-frequency noise. It is my hope that when this filter has been tweaked it will be better than C3D at smoothing out flat surfaces and gradients. This should be good for cartoons/anime, but it actually also helps film footage quite nicely.

## Syntax

Basic syntax: `MipSmooth` - all parameters are optional.

Extended syntax:

`MipSmooth` (clip, optional arguments)

There are a number of arguments that control how much smoothing will be applied:

preset = "MovieHQ" / "MovieLQ" / "AnimeHQ" / "AnimeLQ" / "VHS" / "Rainbow" / "Custom"

Loads a built-in preset as new defaults. See the preset section for more information.

    spatial = 5,
    temporal = 4,
    spatial_chroma =6,
    temporal_chroma =54,
    scenechange = 2.0

All numbers are valid in the ranges 0 - 255 and this defines the threshold for each mode of blending.
The thresholds can be compared to the ones of C3D, except higher thresholds smooth much less than C3D.
The default settings are quite conservative, and only slightly smooths out surfaces.

"Temporal influence" is replaced by overall scenechange detection. Scenechanges will disable temporal processing in either direction. Use "show = true" to display the values on each frame.

method = "strong" / "soft" / "supersoft" / "superstrong" - default: "supersoft"
This setting controls how much blurring is applied. The strong settings makes the filter have a larger impact, whereas soft is more gentle. In general strong should give best results on anime, and soft should be best for filmed material.
SuperSoft / SuperStrong uses a slightly different approach, and in general leads to fewer artifacts. These two are an general a bit softer than non-super modes.

downsizer = "reduce", "point", "bilinear", "bicubic", "lanczos" - default: "reduce"
upsizer = "point", "bilinear", "bicubic", "lanczos" - default: "bilinear"
These two parameters control how the lower resolution maps are created. There might not be a very big visual impact, when using different resizers. Experiments are welcome!

scalefactor = 0.5
This option sets the scale of each mipmap. This is how much each frame is reduced in each iteration. The original resolution is multiplied by this value. Usable values are from 0.2 to 4.0, however only values between 0.4 and 1.5 are recommended. When this setting is 1.0 no spatial blurring is done, but this isn't recommended - use spatial = 0 instead. Experiment with values above 1.0 - they might be useful.
This affects the radius of the blur. The lower the scalefactor is, the bigger the radius of the blur - and the more crosstalk you'll get.

    MipSmooth(downsizer="lanczos", upsizer="bilinear", scalefactor=1.5, method = "strong")

The above script produces very nice gentle smoothing for instance, but is very slow.

weigh = true / false
This option selects whether mips should be weighed based on how blurred they are. The most blurred mips are weighed the lowest. This option is equal to "Weighed Average" in SmoothHiQ, or "soft" matrix in Convolution3D.

This option has only effect if SuperMip-mode is used. It reduces the amount of blur when turned on, so it can be used to achieve higher thresholds without artifacts.

show = true / false
Shows information about scenechange differences, and the settings being used.
This setting will have no effect in RGB24 mode - use RGB32 instead!

storecustom = true / false
This will store the settings being used in the registry.
To reinvoke these presets later, use preset = "custom" parameter.
This will not automatically become the default parameters.

## Presets

Presets are a set of builtin settings to help you get started. The names of the parameters are not case sensitive.

All presets are loaded as default values. That means that it is still possible to finetune preset settings by setting individual parameters.

For example: MipSmooth(preset = "movieHQ", scenechange = 8) will use the MovieHQ, but with scenechange set to 8.

MovieHQ

This preset is for natual movies in high quality.

    Spatial: 4
    Temporal: 5
    Spatial Chroma: 5
    Temporal Chroma: 7
    Scenechange: 2.0
    Method: SuperSoft
    Downsizer: Bilinear
    Upsizer: Bilinear
    Scalefactor: 0.85
    Weigh = true

MovieHQ2

This preset is for natual movies in high quality.

    Spatial: 2
    Temporal: 2
    Spatial Chroma: 3
    Temporal Chroma: 3
    Scenechange: 2.5
    Method: SuperSoft
    Downsizer: Bilinear
    Upsizer: Bilinear
    Scalefactor: 0.75
    Weigh = true

MovieLQ

This preset is for natural movies that need more smoothing, to have more blocks and noise removed.

    Spatial: 8
    Temporal: 7
    Spatial Chroma: 10
    Temporal Chroma: 8
    Scenechange: 3.5
    Method: SuperSoft
    Downsizer: Bilinear
    Upsizer: Bilinear
    Scalefactor: 0.65
    Weigh = true

MovieLQ2

This preset is for natural movies that need more smoothing, to have more blocks and noise removed.

    Spatial: 4
    Temporal: 4
    Spatial Chroma: 5
    Temporal Chroma: 5
    Scenechange: 3.5
    Method: SuperStrong
    Downsizer: Bilinear
    Upsizer: Bilinear
    Scalefactor: 0.65
    Weigh = true

VHS

    Spatial: 9
    Temporal: 6
    Spatial Chroma: 10
    Temporal Chroma: 9
    Scenechange: 5.0
    Method: SuperStrong
    Downsizer: Bilinear
    Upsizer: Bilinear
    Scalefactor: 0.60
    Weigh = true

AnimeHQ

This is for slight blockremoval and gradient restoration. It has more spatial smoothing than ordinary video to help recreate flat and gradient surfaces.

    Spatial: 6
    Temporal: 8
    Spatial Chroma: 6
    Temporal Chroma: 8
    Scenechange: 5.0
    Method: SuperSoft
    Downsizer: Bicubic
    Upsizer: Bicubic
    Scalefactor: 0.60
    Weigh = true

AnimeLQ

This is for more noisy material with more blocks and noise.

    Spatial: 5
    Temporal: 5
    Spatial Chroma: 5
    Temporal Chroma: 7
    Scenechange: 5.5
    Method: SuperStrong
    Downsizer: Bilinear
    Upsizer: Bicubic
    Scalefactor: 0.5
    Weigh = true

Rainbow

This might help removing rainbow flicker. See this thread at Doom9 for info and alternatives. Reduce scalefactor for even more rainbow removal, but more chroma blurring.

    Spatial: 0
    Temporal: 0
    Spatial Chroma: 255
    Temporal Chroma: 255
    Scenechange: 2.0
    Method: SuperStrong
    Downsizer: Bilinear
    Upsizer: Bilinear
    Scalefactor: 0.65
    Weigh = true

Custom

This will read settings that has been stored in the registry, and use these as default settings.
If there is no settings stored in the registry, an error will be thrown.
At any time it is possible to use "storecustom = true" this will then store the current settings in the registry, and these will then be used as the custom parameters

## Examples & Tricks:

Try experimenting with quite hard softening with very low thresholds. For example:

    MipSmooth(spatial=2, temporal=2, method="superstrong", scalefactor=0.75, weigh=true)

This is a quite good setting for high quality material, which will stabilize the image and give much better compression and still retaining a quite high amount of detail. These modes are implemented as "MovieHQ2" and "MovieLQ2" presets.

    MipSmooth(spatial=255, scenechange=0, method="soft")
    # This will give a very soft image - seen in some commercials and soap operas.

    MipSmooth(spatial=255, scenechange=0, method="strong", scalefactor=0.65)
    # This will smooth the image very much like a soft gaussian blur.

    MipSmooth(spatial=255, scenechange=255, temporal=255, method="superstrong", scalefactor=0.6, weigh=false)
    # This will also give a very soft image with some temporal blurring.

When cropping right before this filter, use "align=true" parameter, available in AviSynth 2.5.3 and later. This will in most cases give a slight speedup.

## Background information

"Mip" comes from "MipMap", which is a term used in the realtime 3D-graphics world, and basicly describes a downsampled version of a texture (bitmap surfaces of 3D objects), that is used, when the object is far away. MipMaps are always half the size of the original image.

What MipSmooth does is actually very simple:

It takes the source frame, and creates three new versions, each half the size of the previous. This is done by using ReduceBy2, or a selectable resizer. These frames are then all scaled back up to original size using BilinearResize. These frames are then compared to the original, and if the difference is below the threshold, the information is used to form the final pixel.

The same is done to the previous and the next frame - and all these three frames and their "blurred" mipmaps are used to reconstruct each pixel.
Threshold is adjusted to that more blurred images are given a lower threshold than the sharper versions.

Supermip first creates three frames (supermips) from spatially blurred images and does a temporal softening on these three framres. This greatly reduces artifacts on heavy denoising/blurring.

## Further possible improvements

- Adjustable number of mips.
- Image examples in documentation.
- GUI.

`$Date: 2004/08/13 21:57:25 $`