Old 04-07-2019, 09:12 AM   #1
hermbot
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Default Image overlay zoom very poor quality

Hello,

When overlaying an image in my video, I am using the Video Processor opacity / zoom / location plugin to move my image over to the right in front of some video.

When I use the zoom functionality to reduce the size of the picture, however, the quality of the image goes way down, it gets very pixelated and blurry. Is this normal?

Example: https://imgur.com/Howmbrc

It's a .PNG file, if that matters.
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Old 04-08-2019, 05:23 AM   #2
David Else
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I just had a look at this, and it seems there is some massive problem with Reaper image resize quality. I assuming that the fullscreen preview is the same as the full slow render, here is my very quick rough test:

https://www.learndigitalaudio.com/wp...om-quality.png

Look at the top of the plane in the Reaper render, it is jagged and really bad looking.

I have a horrible feeling we are seeing Nearest-neighbor interpolation, the lowest quality resize algo. If this is the case I am praying we can get at least Bicubic asap:

https://en.wikipedia.org/wiki/Image_scaling

Quote:
Bicubic interpolation yields substantially better results, with only a small increase in computational complexity.
Justin, could you set the record straight on this? I thought FFMPEG used bicubic scaling by default?
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Last edited by David Else; 04-08-2019 at 05:29 AM.
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Old 04-08-2019, 03:58 PM   #3
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Thanks for the reply, at least I know it's not just me!
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Old 04-08-2019, 08:20 PM   #4
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Did you turn the filter parameter to 1 (on)?

You can also use "image overlay" preset (and you'll probably have to enable the filter). This preset will allow you to use PNG which have transparent/alpha.
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Old 04-09-2019, 02:47 AM   #5
David Else
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Quote:
Originally Posted by JamesPeters View Post
Did you turn the filter parameter to 1 (on)?

You can also use "image overlay" preset (and you'll probably have to enable the filter). This preset will allow you to use PNG which have transparent/alpha.
OMG you did it again! Thanks. I did not see the "image overlay", it is not obvious that it is needed as the .png image just displays anyway and the other presets with zoom work too. "image overlay" + filter 1 and results are much better

@hermbot, how about you?
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Old 04-10-2019, 09:08 AM   #6
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with the filter parameter set to "on", overlay zooming results are still far from smooth. The same is true when zooming text overlays. I hope that these issue will get addressed soon.

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Old 05-05-2019, 03:52 AM   #7
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I find the quality with the filter on enough, but the problem is when it comes to animating the zoom parameter with envelope or lfo. The zoom movement is not smooth, it stops for some frames, then zooms it a bit and stops again for some frames. This is clearly visible when the zoom is slow and just a bit. Try to animate the zoom in for example from 3.0 to 3.1 in 30 seconds. If you zoom enough and fast you don't notice. But I cannot figure out how to zoom slowly and smoothly.
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Old 05-05-2019, 06:14 AM   #8
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Quote:
Originally Posted by heda View Post
I find the quality with the filter on enough, but the problem is when it comes to animating the zoom parameter with envelope or lfo. The zoom movement is not smooth, it stops for some frames, then zooms it a bit and stops again for some frames. This is clearly visible when the zoom is slow and just a bit. Try to animate the zoom in for example from 3.0 to 3.1 in 30 seconds. If you zoom enough and fast you don't notice. But I cannot figure out how to zoom slowly and smoothly.
It seems that is exactly the same problem I already discovered here: https://forum.cockos.com/showthread.php?t=214903

This issue even prevented me from creating an example project with a slide show to give an idea whats possible with blend over, zooming, panning etc. I made some tests with Adobe Premiere and it never happened there. But at the moment I'm not into it so ...

Greetings
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Old 05-05-2019, 01:31 PM   #9
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Thank you Eliseat
I am starting to catch up with all the video processing.
Thanks for the link to that thread. It is exactly the problem I have.
I was using the preset "Basic helpers: Track/opacity/zoom/pan" and in RGB colorspace in project settings. Now I changed to YUY2 or to I420/YV12 and it zooms much smoother. I'll keep investigating. So far changing &-2 to $-1 as Justin said in that thread doesn't seem to help in RGB colorspace. I'll just use YUY2 for now

edit: I was testing on a new project and it seemed ok with a normal image. back with the project with the problem which has larger images, larger than the project resolution, and it is not smooth movement/zooming. I need to work with large images to zoom in. So this may not work... I really wanted to generate the video in REAPER

Last edited by heda; 05-05-2019 at 01:40 PM.
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Old 05-07-2019, 12:48 AM   #10
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In fact the "panning while zooming problem" makes it impossible to use Reaper for serious video editing anymore, as I need this very often. That's a bummer because I like the concept of editing video like audio.

But what I didn't know is that it behaves differently in other color spaces. How could that even be?

I will test that in the next days. But it still needs to get fixed somehow, because its very obvious especially for people who come from other video editors. I was pretty surprised when I realized the first time how bad the interpolation works. There must be something overlapping between pan and zoom. I don't know.
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Old 05-08-2019, 04:58 PM   #11
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I posted some examples on that thread you told me. But I am ready to give up now.. and I am just zooming without panning.
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