flickering or "wavy" artifacts along the edges of objects

John-H wrote on 8/23/2025, 6:16 PM

I'm experiencing an issue while editing in Vegas Pro 20. I took a PNG screenshot from a 4K progressive video and applied a slow zoom motion using the Event Pan/Crop tool under Video Event FX. However, in both the preview window when editing and the final rendered footage, the image shows flickering or "wavy" artifacts along the edges of objects during the zoom.

This issue is most noticeable around detailed edges, such as windows, doors, roofs, and similar structures. You can see the problem in the video sample - pay attention to the windows click here https://drive.google.com/file/d/1SFM0vhIqt3H96LqHIIrpClzdekWn7kvY/view?usp=sharing

In my project properties:

Resample mode is set to Disabled

Deinterlace method is set to None

Render output is 1080P 59.94

Video source properties: 4K 59.94

Any suggestions on how to fix or reduce this effect would be greatly appreciated.

Comments

zzzzzz9125 wrote on 8/23/2025, 8:22 PM

@John-H This is the moire pattern produced during scaling. To solve it, add a "Quick Blur" FX to your event.

John-H wrote on 8/23/2025, 9:23 PM

Quick Blur FX dont help😞

EricLNZ wrote on 8/23/2025, 9:51 PM

Try Gaussian Blur with very low values and add as a Media FX, not Event FX.

John-H wrote on 8/24/2025, 11:09 AM

I tried it, and this Gaussian Blur method helped. So I applied it to all affected media, and the final render looks good.
But now the question is: why did this issue happen? The moiré patterns caused by scaling appear on almost all the media in my project.

EricLNZ wrote on 8/24/2025, 5:31 PM

Why does it happen? Basically it's the nature of video images which are represented by pixels in fixed positions. When you have fine sharp lines which are moving the "drawing" of the image is constantly changing which can give a flickering effect. The greater the number of pixels in the image the greater the ability to show the image clearly.

When you scale down from 4K to 1080 you have only 25% of the original number of pixels so your image is struggling to show fine detail like it did in 4K which had four times the number of pixels.

So short answer it's caused by the downgrading from 4K and the reduced number of pixels.

As you've discovered slight softening, reducing detail, can help reduce the problem.