Corona 8 Interactive render becomes blurry after a few passes

[Erik1974]

When i start IR the image appears crisp as usual but after a few passes the image becomes very blurry making the IR unusable.

Anyone else notices this?

[romullus]

That's denoiser kicking in action. If you don't like this, go to render setup>performance>interactive rendering and disable fast preview denoise.

[Erik1974]

Thank you, that was it! Why would you want this anyway, the image is way to blurry like this.

[maru]

It just removes the noise using neural networks. The "blurriness" depends on the specific case and sometimes it does a great job.
Here is more info: https://support.chaos.com/hc/en-us/articles/4528588388113-How-to-use-denoising-

[romullus]

Thank you, that was it! Why would you want this anyway, the image is way to blurry like this.

It depends on one's preferences and also on specific scene. Sometimes you're constantly changing scene and render parameters and want to see result as quickly as possible, then denoising is distracting and you want to turn it away, but sometimes you are willing to wait a bit longer for updates and want to see clean picture that closely resembles final output, in that case IR denoising is very useful. Personally i leave it on 9 times out of 10 and only occasionally turn it off when i really need very fast response.