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Journey on Sudak / Путешествие по Судаку » Все о VirtualDub и его фильтрах » Полный список » Shadow Smoother v0.7 (Valentim Batista)
Shadow Smoother v0.7
ShedrinДата: Четверг, 19.07.2007, 10:32 | Сообщение # 1
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Spatial and temporal smoothing in the shadow areas of the picture.
Shadow Smoother version 0.7 corrects a bug with certain image widths.

Shadow Smoother Quick Cookbook !

* Start by selecting a threshold of 5/7, with strength as 1 and a difference of 2/3.

* Make a second pass and this time aim lower in the shadows but stronger with a threshold of 4/6, strength as 2/3 and a difference of 2/4.

* Difference of more than 4 tend to create artefacts with rough edges appearing on zones of transition. With high differences too much data can be kept from previous frames causing that, instead of reducing temporal noise (this noise is a compression reducer due to the increased data variation from frame to frame) it can introduce new noise thus creating sometimes visible artefacts.

* Keep temporal setting "pixel locking" and "noise locking" on as well as "post smoothing".

* Pixel locking occurs when difference between pixels on two frames (temporally) is roughly half of the configured maximum difference for temporal denoising. On normal temporal process the pixels are blended, on this special case the pixel from the previous frame is kept. This occurs only on the shadow area as by configured threshold.

* Noise locking is a special variation of pixel variation where if a pixel is horizontally sandwiched between two locked pixels then it becomes locked as well.

* Post smoothing enhances compression by applying a last step of horizontal smoothing (a strength 1 of "horizontal smoother") after temporal locking as a way of reducing high frequency components alien to the input material possibly created by the temporal process that would have a negative effect upon compression if they weren't smoothed.

* A third pass could be done over darker areas but this is normally not very productive.

* Warning: Threshold 8 is available and affects the entire picture which is normally not intended and causes a deep degradation of the perceived sharpness of the picture, keeping the smoothing to the darker areas of the pictures gives greater compression without sacrifying image quality so much. Reducing detail on shadows saves bitrate on areas where eye detail perception is physicaly reduced and on areas that are normally out of mind focus, so this can get very much unnoticed normally.

* After "shadow smoother", if your source is good and without noise you can apply a "Vertical Smoother" filter with strength 1, if by the contrary you have a noisy source you can go up to a 2/3 strength, reserving strength 4 to special occasions ...

Пространственное и временное сглаживание в теневых областях изображения
с целью снижения битрейта, необходимого для кодирования темных областей.
Процесс сглаживания производится непосредственно в строке, без вертикального сравнения.
Фильтр оперирует с областями переменного радиуса, чтобы достичь 3-х уровневого сглаживания.

Редирект на скачку фильтра


 
Journey on Sudak / Путешествие по Судаку » Все о VirtualDub и его фильтрах » Полный список » Shadow Smoother v0.7 (Valentim Batista)
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