[Per Holmes]

Hi Dan,

Great! I mean Great 🙁

Please leave the PNG file on your server, I’ll leave mine as well so this thread may serve some value for a while.

I’m also always seeing the halo on the right side. I’m noticing one thing quite clearly on your shot because of the contrast between the shirt and the background, that your left side has a corresponding white rim which I’m sure is not a backlight. This therefore reeks of a chroma-shift of a couple of pixels. However, when I convert to YUV and shift the UV channels to the left two pixels, it doesn’t look right.

I think that at least one possibility is that it is the result of how a higher resolution image is assembled from lower resolution CCDs, which is usually photographically irrelevant, except when you do dramatic color and contrast shifts as you do around subject edges on a green screen.

Another thing that has struck me is the possibility of the infra-red light used to run the auto-focus, that it somehow front projects on the green screen and comes back as a shadow, like a flash on a camera. I think this theory is not really plausible, but I’m grasping at straws to come up with an explanation.

For sure, I think the ‘lighting explanation’ is bankrupt, that lighting is somehow the cause. There is no law of physics that allows that kind of ‘dark matter absorbtion’ literally outside the subject. That’s total science fiction. If different lighting for some people makes it go away or minimizes it, then they’re really just suppressing the effects of the problem — dark clothes transition with the black halo so much that you can’t see the halo. It’s not really gone.

Anyway, thanks for posting! I hope we figure out what it is. And if it’s fundamental to the design at this fairly low price point, then I’m totally fine. But if it’s a bug, it should be fixed for the benefit of everyone.

Per

[Per Holmes]

Hi Dean,

Thanks for your post. Yes, it’s very common to use even 5 or 6 keyers, one optimized for hair, other keyers optimized body, shadows, contact shadows etc. Also, several keyers is the way to handle a green screen that is not evenly lit, and with a cyc, it’s almost impossible it to get it completely even.

Several keyers don’t actually fix this particular problem, because since the issue affects one entire side of the actor, including their hair, there’s almost no way to avoid some sort of rim with the keyer alone, without eating considerably into the edges. The edge itself needs to be evened out before it’s fed to the keyer, and treating the halo as if it’s a chroma echo, as described earlier I’ve been quite successful doing a sort of ‘reverse chroma echo’.

I still can’t figure out this issue, although I’ve determined that the HVX-200 is not the only camera to exhibit it. My Nikon D70s also has it, but since I have no way of knowing what kind of edge treatment they do, I don’t want to use it as an absolute reference, or even say for sure that it has the problem natively.

The D70s uses a Bayer pattern on the CCD, meaning that the RGB image is assembled from underlying CCDs that themselves have lower resolution than the final image, and for most types of photography, this is perceptually irrelevant. The HVX also assembles an image from CCDs of lesser resolution, and although what the HVX does is completely different. But the bottom line still is that the color channels from the CCDs (or single Bayer CCD) are assembled in unique ways to produce a resolution that is higher than the native CCDs. Normally, it’s not a problem, but it may give these cameras a hard time with extreme changes in color.

Regardless, since I’ve seen DVX-100 Andromeda (4:4:4 10-bit) footage that didn’t have the halo, I’m still extremely curious what the actual native data from the CCD in the HVX looks like. I’m not completely convinced that the halo is not an artifact from some DSP processing, something that could possibly be disabled, yielding a yet more powerful camera basically for free.

Best,

Per

[Per Holmes]

Thanks!

Per

[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

[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

[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

[Per Holmes]

What a bizarre response some people have to a perfectly legitimate inquiry.

[Per Holmes]

Dear Jan,

Thanks for responding.

Well, it’s not very hard to find other people. Searching for ‘hvx green screen halo’ on Google, here are a couple of links. I’m just grabbing these without reading them again, so maybe one of them is something else.

https://dvinfo.net/conf/showthread.php?t=86997&page=2

https://www.dvxuser.com/V6/archive/index.php/t-88916.html

I communicated privately with the DV Info poster, who I think finally had talked himself into lighting being the cause (an even easier solution is to have everyone wear black, it matches the halo making it invisible), and had made what I consider a hefty (as a solution) 50 node Shake setup to remove this chroma echo thing. His setup included rotoscoping the halo, and my line of thinking then, why bother shooting on green screen at all, why not just roto the whole thing.

Regarding the Detail settings, I can say with certainty that the Detail -3 advice is not good advice. -3 simply has more edge sharpening than -7. If you read all these posts, I agree that -7 is actually OFF, at least on the Luma signal. The halo is still there in the chroma signal.

I have followed everyone’s large and small ideas to the utmost. There is no lighting solution that takes it away. There is no resolution and no setting that takes it away. Everyone who has uploaded footage that supposedly is without a halo CONTAINS a halo, or keying where the matte has been shrunk too much. In that case, I like my solution better, to reverse the chroma echo by 2 pixels as I described and then doing light wrap over bright areas. This actually produces a fully respectable key and retains practically all hair detail and semi-transparency.

I would absolutely LOVE to see a 1080p uncompressed still of a green screen that is without halo, and where the subject has a non-black edge, which would conceal the halo. Please send still to sales@hollywoodcamerawork.us.

I do still strongly believe the conclusions I have arrived at in this discussion, that this halo is a consequence of that pixel manipulation that is taking place to produce an image that is not a one-to-one pixel copy of what the CCD is seeing. All kinds of processing is taking place to do that, which is usually perceptually irrelevant.

And I’m not saying that this is wrong. You’re obviously providing amazing value for money with this camera, no doubt, and it’s OK to pull a few tricks to make it happen. If it is native to the way it designed, then I’m fine. I just don’t want it to be a bug, or something we’re all in denial about.

All I started out saying was that if this is simply caused by a detail generator not turned all the way down, even with the lowest settings, then I would spearhead a petition-drive to get a firmware that allows it to be completely disabled.

Best,

Per

[Per Holmes]

Hi Marcus,

I should only add, that the halo could also be caused by the pixel shifting process. As I understand it, the native CCDs in the HVX are actually not very high resolution, and the higher resolution is gained by interleaving these signals, which logically implies that some technical assumptions about being made about a certain chroma value the same way 4:2:2 makes assumptions about chroms that 4:4:4 does not (same chroma every two pixels). The pixel shifting process would necessarily do something similar to create 1280×1080 from 3 540×540 sensors (if that’s the exact number).

If that’s the case, then the halo is physically part of the camera design, and possibly most visible on a hefty change in color information such as going from a green screen to a person’s arm.

But if it’s physically part of the signal after the pixel shift, then I have no quarrel, because then that’s how Panasonic was able to deliver a camera with this resolution at this price. In that case, you get what you pay for, and that’s fine. I just want to make sure that we’re not dealing with some engineer not seeing the need for completely disabling an Unsharp Mask algorithm, which could eventually be fixed in software.

I’m going to do a little research on my Nikon D70s and find out if it does any pixel shifting, or resolution extrapolation. Probably not, as it is a 1 CCD camera, naturally, it’s a DSLR, but you never know. Otherwise, the Nikon is producing the halo as a function of a sharpness generator that is not completely off, but I don’t feel like starting to analyze a whole new camera.

But if the halo is inherent to the design, I have no beef. And it could well be. Raylight should then consider doing as an option what I did in Fusion, which does a quite good job at removing the halo by echoing the UV channels two pixels in the opposite direction and adding them back on top of they hold higher values.

Anyway, thanks for all your attention.

Cheers,

Per

[Per Holmes]

Hi Steve,

I’m split between Los Angeles and Seattle.

But what a curious comment. I’ve done everything Jan suggests times a thousand. Before she asked. She suggested to change the detail settings. I told her that I’ve done meticulous and graphed analysis of over 60 combinations of the Detail and V Detail settings. I have done EVERY SINGLE COMBINATION. Jan’s answer was down the same alley as ‘are you sure you’ve plugged in the power?’.

But it appears you’ve not read the entire thread, which is still there for your perusal.

Best,

Per