Max VFB output with artifacts with sharpen/blur enabled (CIE output is fine)

[pokoy]

So this is something that dates way back to the first stable releases. It was mentioned a few times and reported afaik but it seems to be still there. Output shown here is from Corona 3 RC4.

If you enable sharpen/blur in Corona's VFB in Max, the output (saved to 16bit TIF here) will show serious artifacts. However, the same output, saved to CXR from Max, opened in CIE and saved to TIF will how no artifacts. See attached images and scene file (images were made brighter in PS to display the problem, max file is 2018).

Can we make sure this is fixed for v3? Basically, it means that all output from Max VFB to anything else than CXR (or TIF in any case, didn't test other formats) will show this artifacts when using sharpen/blur.

[maru]

It could be a 3ds Max issue, but we will look into it.
Please see if the same thing happens when saving to EXR.

[pokoy]

Sorry, I won't have the time. I think it should be made sure from your side that the VFB saves correct output, after all there's a lot to test, I really can't go through this due to time restrictions.

[romullus]

Is this only TIFF related? I'm using sharpen in VFB quite often, but never saw artifacts in saved pictures (8bit PNGs mostly).

[pokoy]

Is this only TIFF related? I'm using sharpen in VFB quite often, but never saw artifacts in saved pictures (8bit PNGs mostly).

Can't say, tested TIF output only so far.

[TomG]

Seems to happen regardless of format - I tried TIFF, PNG (24 bit and 48 bit), and even JPG, and the same "dark haloing to the edge" was visible on brightening in Photoshop (Brighten adjustment layer, Brightness to 150) for VFB saved images vs CIE saved versions.

EDIT - including the JPGs here in case the banding in them, which is also different from CIE and VFB, might be a clue? Not that the banding is there, that's expected, but rather than the VFB and CIE are giving different results :)

[romullus]

Hmm, i tried to reproduce it, but i don't get any artifacts, just very subtle difference.

[pokoy]

Now it's getting interesting!
Romullus, you are applying the level shift in PS, right? The issue is invisible without any heavy gamma shift/brightness + contrast.

[romullus]

I did like Tom said - added brigthness adjustment layer and increased brightness.

Maybe it has to do something with sharpness settings in Corona, or maybe it matters how you save the file? I tried with default sharpening settings and i saved image from VFB to PNG and to CXR and then CXR to PNG in CIE.

[TomG]

The sharpening here in the example file is pretty extreme, set to 7 (I didn't see any obvious difference with a quick test scene with the default values). Of course even when extreme, I'd expect VFB and CIE to give the same results :)

[pokoy]

Romullus - could you open the original scene, make sure sharpening is enabled, save out a TIF from Max VFB, save as CXR, open the CXR in CIE and safe out a TIF and compare then, or even post the results here? If you are unable to reproduce, maybe the issue is elsewhere... who knows.

Tom, I also noticed the different banding... really strange, do you have any clue what might be at work here?

Also, I have exaggerated sharpening in the example scene but I'm seeing the problem on production scenes with only subtle sharpening, too. The more highlights and reflections in the image the worse it gets. I'm attaching two examples with subtle sharpening, the problem is very much visible here.

In any case, the problem might be close to invisible in normal circumstances but I now remember that I had a hard time composing a few projects with AE in 32bits because of this. I'd get problematic alpha cutouts when using plugins or blurring highlights, pixelated artifacts around object, all kinds of headaches.

[romullus]

Romullus - could you open the original scene, make sure sharpening is enabled, save out a TIF from Max VFB, save as CXR, open the CXR in CIE and safe out a TIF and compare then, or even post the results here? If you are unable to reproduce, maybe the issue is elsewhere... who knows.

Unfortunately max 2016 can't open your scene - it is saved in more recent version.

[pokoy]

Ah sorry, max 2016 file is attached, Corona 3 RC4.

[romullus]

Ok, i can confirm - with your file, i get those artifacts too.

[pokoy]

Many thanks! Hopefully dev will be able to track this down.