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Old 23rd February 2020, 07:51   #1  |  Link
Sakura
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AreaResize

Hello! I port AreaResize to VapourSynth, based on the original AviSynth verison by Chikuzen and the modified AviSynth version by Aktan.

AreaResize is an area average downscale resizer:
  • Support 8-16 bit and 32 bit sample type.
  • Support YUV and RGB color family.
  • Downscaling in 8-16 bit RGB with gamma corrected.

Usage
Code:
core.area.AreaResize(clip clip, int width, int height[, float gamma=2.2])

# Parameter "gamma" is for gamma corrected, only using for 8-16 bit RGB input
Github: https://github.com/Kiyamou/VapourSynth-AreaResize
Download: https://github.com/Kiyamou/VapourSyn...esize/releases

There is known bug for special target size, such as 1920x1080 -> 1200x700 for 8~16bit YUV and 8bit RGB.
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Last edited by Sakura; 21st March 2020 at 09:04.
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Old 24th February 2020, 02:29   #2  |  Link
Lypheo
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Could you perhaps explain the algorithm behind this? How does it differ from conventional convolution-based resizers?
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Old 25th February 2020, 15:05   #3  |  Link
Sakura
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Quote:
Originally Posted by Lypheo View Post
Could you perhaps explain the algorithm behind this? How does it differ from conventional convolution-based resizers?
I have something, causing me reply slowly.

This algorithm is simple, just calculating the average of pixel. (So it is fast.)
For example, 1080p->720p, greatest common divisor: (1920,1280)=640, 1920/640=3, 1280/640=2.
So calculate the value of dst like this:
Code:
y_dst[0] = (y_src[0] + y_src[0] + y_src[1]) / 3
y_dst[1] = (y_src[1] + y_src[2] + y_src[2]) / 3
...
After calculating, the width of clip is changed from 1920 to 1280. And then use the same method to calcuate for height.

Compared other conventional convolution-based resizers, firstly it can be only used to downscale.
From the aspect of effect, I think AreaResize is better than Bicubic, while Spline and Lanczos is better than AreaResize.
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Last edited by Sakura; 21st March 2020 at 09:04.
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