Blue noise integration for bloom

[werner.poetzelberger]

We discovered that the blue noise integration for the bloom in te composite.frag shader is not perfect. 

It brightens up the background slightly that you cannot get a 100 black color. 

When commenting out in the shader it is perfect. Maybe there should be an render option for that or a different integration. 

Found that out on an ledwall when cranking up the gamma. 

Attached an image where u can see the pattern. 

Best. Werner 

[silent]

Hi Werner,

That's pretty interesting observation :)

Can you show us modified composite.frag shader?

 

Quote

Found that out on an ledwall when cranking up the gamma. 

How did you adjust gamma in this case, could you please give us some additional information about this?

Thanks!

[werner.poetzelberger]

Just commented out the last line, 136 i think, where the noise is added to out. 

The result is perfect black, but the bloom is visible geberating bands. Therefore we use the post material, noise. That helps to minimize the banding visibility. 

Gamma... We turned up te gamma of the led wall itself, which made the very dim color values to appear. 

Interesting is, that we use the hdr option of windows, as the led supports that. 

How do we get Unigine to render a hdr image output? 

The final render output is still 8bpc isn't it? 

B w. 

[silent]

Yeah, the final output from the Engine is not and actual 10-bit HDR image.

And it also looks like that there is very little we can do about. If we would not use dithering (in composite.frag), you will see banding and vice-versa. Maybe you can revert contrast back and adjust color via engine itself (not sure if it would be any better, but who knows).

How do you apply your noise, btw? Can you show us an example of your noise? It's pretty much strange that in case of your noise it can't be visible on LED wall, but in case of built-in noise you can clearly see it. Or you simply don't like the repeating patterns?

Thanks!

[werner.poetzelberger]

I used the 2dpost material color correction, which includes chromatic aberration and noise.
This noise was also visible if I turned it up too much, when using just with a very small amount it was working (0,05 or such factor).

It is animated as well. so it felt more like a white noise.

Basically the fact, that it was adjustable, helped. (with the slider). The other noise is fixed and we could only get rid of it, only by commenting it out.

The built in noise was always adding a small amount of brightness, which was visible on the wall (actually it was also visible on a usual screen, but only if you compare it with a 0,0,0 - black color).

Anyway. Good to find out these things, and that we could solve that mystery :)/ Shoutout to Helmut, our brilliant programmer.

The HDR pipeline is interesting I guess now with the possibility of HDR ability of displays. Learned that just now, but will look into that further.

I will discuss and investigate that further in house.

best. Werner

 

 

Edited October 22, 2021 by werner.poetzelberger