To Jan Crittenden: HVX-200 Green Screen Halo Problem

[John Cummings]

I’m sorry, Per.

After spending a fair amount of bandwidth reading the entire thread, I felt I was entitled to inject a little subtle humor into it. Perhaps I was too subtle.

My point is that the HVX is (arguably) a prosumer camcorder, and perhaps you are tad bit unrealistic in your expectations.

My apologies and feel free to continue your harangue.

Happy Holidays-
John

J Cummings
DP/Chicago
http://www.cameralogic.tv

[Cowdog]

[ChicagoShootr] “Or, it may indeed be that the flux capacitors are out of sync with the holographic emitters.”

Yes, but as any good Star Trek fan knows, all you have to do is reverse the polarity of the quantum flux and then all is right with the world…

:o)

Yer pal,

Cowdog

visit my homepage

[Jeremy Garchow]

[Cowdog] “[ChicagoShootr] “Or, it may indeed be that the flux capacitors are out of sync with the holographic emitters.”

Yes, but as any good Star Trek fan knows, all you have to do is reverse the polarity of the quantum flux and then all is right with the world…
“

Great Scott!

[Per Holmes]

Hi John,

I’m sorry! In that case, no problem!

All my green screen experience is 35mm through a beautiful telecine direct to disk at 10 bit log, so admittedly, my expectations are at the high end of the spectrum.

I actually bought this HVX for the sole purpose of doing a specific green screen thing, so this is sort of my first non-casual green screen experience with a prosumer device. Discovering this halo phenomenon, and believing it to be an edge enhancement because it looks exactly like it, has the same width in pixels, and is increased by increasing the detail settings, I wanted to get rid of it.

Even though the HVX is prosumer, I don’t think there’s any real reason for there to be a halo, unless it’s simply inherent to the design and what makes that camera possible at that price. And especially if it is not native from the CCD, the DSP code really should be tweaked on the spot to get rid of it.

I wasn’t expecting this from the HVX, especially because I’m doing SD and would be downsampling DVXPROHD 4:2:2 to uncompressed 4:4:4 in SD res, so I thought I would actually be working at a lower resolution than the native CCD and therefore be in great shape. From a prosumer camera, I was expecting higher noise, more chromatic aberation, more fisheye distortion, more compression artifacts. I didn’t, and still don’t, necessarily believe that the halo has to be there.

But even if it’s a bug, I’ll be long done before it’s fixed, so I’m happy that all this yielding a couple of hacks that essentially kills the halo. That’s why it would be much better for me if this were user-error — then I could simply do it differently and be fine.

Anyway, thanks for your attention!

Cheers,

Per

[Steve Wargo]

You’re right, I did not read every detail and I should have. My apologies. Good luck.

Steve Wargo
Tempe, Arizona
It’s a dry heat!

Sony HDCAM F-900 & HDW-2000/1 deck
5 Final Cut (not quite PRO) systems
Sony HVR-M25 HDV deck
Sony EX-1 on the way.

[Jan Crittenden livingston]

Per,

If you read the responses to the original post you will see that many point to the potential issues that the poster was not paying attention to in his original green screen work, like lighting, scene file set up. Nowhere in the thread does it show that there are lots of people having the problem, it is one guy that has something out of whack in his set-up and the rest are suggestions on how to fix his set-up. And some of the suggestions are to use a different keyer, as they are not all built equally.

I do not have an uncompressed still as all of the green screen I have is in the DVCPRO HD codec.

You can choose to believe what you wish about the pixel offset, but your assumptions may not be correct. Turning the detail all the way down on a key is a mistake.

All the best,
Jan

Jan Crittenden Livingston
Product Manager, HPX500, HVX200, DVX100
Panasonic Broadcast & TV Systems

[Per Holmes]

Hi Jan,

Thanks for responding, but again, this is a somewhat dismissive response that gives little or no credit to the very detailed information collected and posted in this thread.

Regarding more people having trouble, those were the post where people complained. To find some references, I scoured the internet for people’s HVX green screen uploads, and found identifiable halos on essentially everyone’s shots. I exclude some shots because with black clothes and black hair, it’s hard to see whether there’s a halo or not, and some shots were like that.

Regarding settings being out of whack, or the subject somehow lit wrong, I find your explanation bizarre. Unless there’s some magic pixie dust refracting some light OUTSIDE the actor, CLEARLY TO THE SIDE OF THE ACTOR, this just not physically possible, like anti-gravity or teleportation or tractor-beams are not possible. The only possibility that lighting can even be a factor is if certain lighting scenarios trigger a design limitation or a technical limitations in CCDs, and also in the HVX.

I have literally gigabytes upon gigabytes of proof. There’s no lighting setup that change the halo. There’s no scene file setting that can change the halo, and I have meticulously shot elaborate test using all scene file settings.

I find it fantastic that you have ignored essentially everything I have posted, and brushed it off as some sort of user-error. My intelligence is very offended.

I would SO LOVE TO BE WRONG, because then I could push a button and have everything be great. If there was a software or a design problem, and it could be fixed, it would likely take a very long time to receive a fix. I have therefore ZERO INTEREST in there actually being a problem.

But shooting probably all together 30 P2 cards worth of test footage, going through every value for every settings and every possible lighting scenario, there halo is the only constant.

I’m disappointed that you did not upload any green screen footage as evidence that there’s no halo. If anyone could show me a single green screen still shot on the HVX that does not have a halo, I would apologize and shut up immediately. But such a green screen shot appears elusive.

But alas, there is no willingness, and I really don’t care anymore because I have a fix that essentially works, with not a lot of tweaking.

So, anyway, thanks for your time, although I’m disappointed that you did not take a serious and scientific inquiry more seriously.

Best,

Per

[Jon Kline]

I’ve heard that the detail settings are relative, depending on gamma settings. Just thought I’d add that to throw a monkey wrench in the works.
reference: https://www.dv.com/columns/columns_item.php?articleId=193001363

P2 Drivers and Utilities for Mac and PC

[Per Holmes]

Yes, I read that the Cine gamma curves make the detail settings relatively less impactful. I confirmed this by doing Detail -7 to 0 and V Detail -7 to 0 for several different gammas.

Best,

Per

[Gunleik Groven]

Hi Per

Interesting to read this post!

And I can only concur with all your findings.

Started a similar thread over @ dvuser and was pointed here.

https://www.dvxuser.com/V6/showthread.php?t=118788

Not as well documented as yours, but basically describing the same symptoms -:)

Thanks for your time in describing this issue!

Gunleik