Video Quality Lost - Input to Output

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Zyper
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Video Quality Lost - Input to Output

Post by Zyper »

Hello,

I'm actually triyng a lot of setup to check the overall video quality on the output.

Before going into the complex slice transform setup I'm trying to understand this :

I put 4 squares of 250x250 next to each other, and make 4 250x250 slices that fit perfectly on it.

Image

But on the Output I always have a 1 pixel fade around each slice.

Image

Is there a way to have a perfect edge on the output ?
Attachments
INPUT.PNG
Output.PNG

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He2neg
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Re: Video Quality Lost - Input to Output

Post by He2neg »

For me the edge looks like a softedge enebled thing.... are you sure there is no softedge going on on slice lvl?
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Zoltán
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Re: Video Quality Lost - Input to Output

Post by Zoltán »

You're at 4700x zoom...
These are two 1x1 px sources 1 pixel apart at the same zoom level (input)
Képernyőfotó 2020-03-09 - 9.01.05.png
Output:
Képernyőfotó 2020-03-09 - 9.07.14.png
Actual output:
Képernyőfotó 2020-03-09 - 9.09.03 (2).png

You see the fades on the slice edges because of how the algorithm of the scaling works.

Do you see the gap on our actual output?
Are your slices positioned at whole pixel, or a fraction?
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He2neg
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Re: Video Quality Lost - Input to Output

Post by He2neg »

achievement unlock *eagle eye*
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ludodo01
Met Resolume in a bar the other day
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Re: Video Quality Lost - Input to Output

Post by ludodo01 »

Hi everybody !

Why do we lose in quality with Resolume ?

A simple example : I have the same image as my desktop wallpaper and in Resolume.
So I send this image on my LED screen via 2 different ways but it's the same image, same resolution and no transformation.
Why do I lose in quality ? Check the images : the first one is the output of my desktop straight from Windows and the second is throught Resolume. The difference in quality is huge !

Desktop :
Desktop.jpg
Resolume :
Resolume.jpg


Second example :
I have 2 LED panels, 168x168 px each.
I send a "Solid Color" via a "slice transform" in the first panel.
Why does it spill on the second panel ? It shouldn't !
2.png
3.png
IMG_20200309_161541.jpg
Even if I move the panel by 10px in the "Input Selection", the issue seems fixed in the "Output Transformation" but it doesn't ! It still appears on the second panel !

Do you have any solution ?
Thank you for any help you can provide !

Zoltán
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Re: Video Quality Lost - Input to Output

Post by Zoltán »

ludodo01 wrote:
Mon Mar 09, 2020 17:14
Why do we lose in quality with Resolume ?
Windows and the second is throught Resolume. The difference in quality is huge !
Check windows display scaling, make sure it's set to 100% for your output.
Check that you have the slices sized and positioned /sized to whole pixels, and not a fraction of pixels.
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Joris
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Re: Video Quality Lost - Input to Output

Post by Joris »

You see the fades on the slice edges because of how the algorithm of the scaling works.
Why is there scaling involved? A 1 pixel square is getting translated to a 1 pixel square. What we're seeing in your image on the output transformation is interpolation of a pixel with its neighbouring pixels. What we're seeing in Zyper's image on the output transformation is the same interpolation of a pixel with its neighbouring pixels. I don't understand why this interpolation happens. If I'm sampling a single pixel, I shouldn't see that pixel mixed with the color of its neighbour.

Joris
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Re: Video Quality Lost - Input to Output

Post by Joris »

- make two solids on two layers
- make each 10px by 10px
- make the first red and move it to -5 on the x
- make the second green and move it to +5 on the x
- open the ass
- make two slices, 10px by 10px
- put the first on 955 on x
- put the second on 965 on x
- they will now each sample the solid perfectly
- on the output, match input shape and move the slices apart by let's say 10 pixels
- now zoom in and examine the edges

Expected result: each slice contains only the color of the solid it is sampling
Actual result: at the edges, each slice will contain the color of the solid its sampling, interpolated with its neighbour. This result in visible errors and unwanted bleed.
input.png
output.png
Notice especially the green bleed on the right side of the left slice. That's bad.

ludodo01
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Re: Video Quality Lost - Input to Output

Post by ludodo01 »

Zoltán wrote:
Mon Mar 09, 2020 18:11
Check windows display scaling, make sure it's set to 100% for your output.
Check that you have the slices sized and positioned /sized to whole pixels, and not a fraction of pixels.
Fucking display scaling.....

Thanks !!!!

Joris
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Re: Video Quality Lost - Input to Output

Post by Joris »

So I've been doing some reading on this. Turns out this is indeed 'just how scaling works'. The GPU looks at the neighbours of the original texture to guess what the newly created extra pixels should be colored. And zooming in on the output preview like that is in fact applying scaling.

As long as there is no scaling applied on the slice itself, and the slice is positioned on whole pixels, there is no bleed and no problem. I stand corrected.

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