Searching for anti-aliasing information

Hi,
I am conformer and colour grading assistant on the Davinci Resolve station for Eclair Cinéma d'Ymagis, I am looking for an anti-aliasing solution.

Currently on the realization of several series fiction we are looking for a tool or an anti-aliasing method that does not apply globally on a project but on a case by case basis. A solution of the clip type attribute that would correct the aliasing of the desired plans. Currently realized by DVNR on some program plans, we are looking to modify our workflow to integrate it into our main tool.
Is there a method in Resolve or an OFX plugins?

Not speaking English, I translate with Google translation and apologize in advance for translation concerns.


Bonjour,
Conformateur et assistant étalonneur sur station Davinci Resolve pour la société Eclair Cinéma d’Ymagis, je recherche une solution d’anti-aliasing.

Actuellement sur la réalisation de plusieurs séries fiction nous sommes à la recherche d’un outil ou d’une méthode d’anti-aliasing qui ne s’applique pas de manière globale sur un projet mais au cas par cas. Une solution du type clip attribut qui permettrait de corriger l’aliasing des plans souhaités. Actuellement réalisé par le DVNR sur certains plans des programmes, nous cherchons à modifier notre workflow pour l’intégrer à notre outil principal.

Existe-t-il une méthode dans Resolve ou un plugins OFX ?

Ne parlant pas Anglais, je traduis avec Google translation et m’excuse par avance des soucis de traduction.

You can currently apply de interlacing logic to media files in the media pool by just right clicking the media file or files and choosing Clip attributes and then clicking the check box for "Enable Deinterlacing".

I have seen that work well on truly interlaced media files to give them a progressive feel, it is not a true progressive conversion in my experience so your milage may vary depending on your source.

I don't think he is talking about "interlaced" material, but legit aliasing one...

Hi,
Actually I'm talking about anti-aliasing and not the interlaced.
I'm looking for an OFX that allows me to do that.
Aliasing appears after conversion of RED, ALEXA and others native UHD to HD.
The UHD version is perfect but the HD version is not clean with the scaling output to Resolve.
We transform the UHD version of the Resolve into HD through the Vantage software to have a clean version.

try to set the scaling option to "smoother" when you do the HD pass.

I would bet that not every shot suffers from aliasing. Be aware that sometimes your monitor may be exaggerating the aliasing and giving you a false impression of how severe it is. What kind of display are you using and how is it calibrated?

Hi,
Actually I'm talking about anti-aliasing and not the interlaced.
I'm looking for an OFX that allows me to do that.
Aliasing appears after conversion of RED, ALEXA and others native UHD to HD.
The UHD version is perfect but the HD version is not clean with the scaling output to Resolve.
We transform the UHD version of the Resolve into HD through the Vantage software to have a clean version.

Most resizing algorithms that I've observed either do not employ low pass filtering when down-sampling or employ only a very small amount. So the result is aliasing.

Applying a small amount of blur prior to re-sampling may be all you need to reduce the aliasing to an acceptable level. Note that this is NOT the same as trying to use blur on footage that already has aliasing artifacts. When you do that, you simply get blurred artifacts. Blurring prior to down-sampling reduces the aliasing at the root cause. I'd suggest trying blurs between .7 and 1.5 pixels. There is no perfect number because there is no perfect low pass filter. You simply pick the best compromise for you footage and preference. You may find that it is also desirable to apply a very small amount of sharpening to the footage once it has been down-sampled.

Hi,
Actually I'm talking about anti-aliasing and not the interlaced.
I'm looking for an OFX that allows me to do that.
Aliasing appears after conversion of RED, ALEXA and others native UHD to HD.
The UHD version is perfect but the HD version is not clean with the scaling output to Resolve.
We transform the UHD version of the Resolve into HD through the Vantage software to have a clean version.

I looked up Vantage software and they claim to be a high quality service. So it seemed odd that they wouldn't low pass filter the footage. So I peeked into their manual and found that they have low pass options to use when scaling down. Go to page 340 for details. I suggest dealing with the problem at its source. Trying to deal with it downstream is sub-optimal. You don't really want to remove aliasing. You want to prevent it from showing up to begin with.

http://www.telestream.net/pdfs/user-gui ... -Guide.pdf

Oh - and take Marc's advise. Make sure that your footage actually has the aliasing and that source of the observed aliasing is not your monitor/display chain.

Hi waltervolpatto,
The smoother option degrades the image too much in quality. Currently we go out in UHD sharper and realize the downscaling UHD to HD with the vantage which degrades less the quality than the smoother of the Resolve.
We use the smoother only for the SD of DVDs

Hi Marc Wielage,
We use a SONY X300 monitor for color grading, a LG 31MU97 computer monitor for conformation and mastering, and a BON BXM-323L3G monitor for verification and aliasing correction at DVNR.
The three monitors reveal the aliasing more or less present.

Hi Jay Turberville,
Thank you for your approach. For lack of effective anti-aliasing in the Resolve, I will try this approach and try to fix the problem with a blur on the affected areas. I would keep you informed of my research

Do you monitor over progressive signal, 24p, 25p etc. or over interlaced?
Working with progressive footage but monitoring over interlaced chain will show this problem. It's actually good to see it, if you know your master will go over broadcast which will most likely use interlaced chain. You should make special version for this use which is less sharp.

To sharp HD is nothing that good. Looks digital. As you said you need low pass filter. From pro solutions Nucoda has one in their DVO plugins pack.
One of the solutions is to blu/sharpen/blur/sharpen as this creates low pass filter.

You also have to be prepared that in order to avoid aliasing on interlaced chains footage has to be less sharp and there is no way around it. Same applies for HD to SD conversion, e.g. DVD. You always have to make compromise.

Episode's low pass is to strong- I never managed to convince Telestream to make it adjustable (now to late as Episode is discontinued).

We changed our workflow.
The program is checked in the Resolve after calibration. The BON BXM-323L3G monitor and an oled LG TV allow you to watch the sequences to go to Nucoda. We export aliased sequences (1 to 2% of the program) and process them at Nucoda. The Nucoda has a superior quality of treatment with its low-pass filter.

Nucoda low pass filter should be decent.

I have dealt successfully with RED based aliasing at the debayering stage. I can't remember the specific parameters though. Most of it can be arrested before data is converted from RAW to RGB. On occasion I'd use a bit of low pass filtering to soften some high frequency detail like leaves in the tree or tiles on a roof. However, none of this was in Resolve, but the same debayering techniques should apply.

Debayering setting is not going to directly help (if you want to debayer at full resolution). Problem happens when you start with high resolution image (e.g. 6K RED) and going to lower resolution, e.g. HD, specially for interlaced standards. Depending on the actual footage it can have simply way to sharp details (to high frequencies).

better check out if it is actually necessary,
so first "generate optimized media"?