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Old April 13th, 2006, 12:47 PM   #1
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JVC HD100 or Canon XL H1 for green screen?

Greetings,

Has anyone had experience shooting green screen with tracking markers with both of these cameras? Would you recommend one over the other? The higher resolution of the XL H1 would be helpful, but as the progressive mode is interpolated I do not know if it will actually resolve higher resolution than the JVC. All opinions are welcome.

We will be shooting 30p.

Thanks
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Old April 13th, 2006, 01:43 PM   #2
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Quote:
Originally Posted by Brad Abrahams
Has anyone had experience shooting green screen with tracking markers with both of these cameras? Would you recommend one over the other?
Hi Brad.
I didn't try the Canon but I just finished shooting about 20 minutes of footage with GS with the HD100. The results are good, I can pull clean keys very fast with the green spill being the only issue and that one is pretty easy to fix too.
It's a pretty safe assumption that progressive scan is the best way of shooting GS.

Cheers.
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Old April 13th, 2006, 03:53 PM   #3
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Yes, true progressive recording will yield a better key than interlaced footage.
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Old April 13th, 2006, 04:06 PM   #4
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When the TX Shootout results become available, I suspect the answer will be, "It really depends on your price point."

My early impression is that the F modes in the Canon (which are put onto tape as true progressive) have at least as much picture detail as the JVC when both are using HDV. So keying HDV material probably isn't hugely different in the two cameras. If you have the extra dollars to do HD-SDI out (1920x1080p24 or p30 at 4:2:2) from the Canon to a high-end computer, that will unquestionably result in a better key. But again, your getting into a LOT more money.
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Old April 13th, 2006, 04:51 PM   #5
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The Canon will produce results at least as good as the HD100, provided you're able to get at the progressive frames correctly. The XLH definitely is a higher res camera...in 24F it becomes a bit softer though.

The XLH writes the frames as progressive to tape, it's the MPEG decoder that adds the interlace. The DSP leading to the HD-SDI out also adds interlace, but it's in an uncompressed state. So the two paths would be:

1-Use a firewire/HDV capture that either re-encapsulates to progressive frames, or writes raw .m2v to tape. If the raw mpeg2 data is recompressed to an intermediate codec, make sure that decoder step doesn't add interlace.

2-Capture via uncompressed HD-SDI, then remove pulldown to another uncompressed file.
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Old April 13th, 2006, 11:34 PM   #6
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From Tape the HD100 will be better but don't foget that you can go out of the HD100 at true progressive and 4:2:2.
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Old April 14th, 2006, 11:48 AM   #7
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The best way to do it with the HD100 ultimately would be a live capture out of the component outputs, thus completely bypassing the HDV compression step.

One thing a lot of people don't consider about the 720 vs 1080 for the JVC is that it is FULL 1280x720 with absolutely no sub sampling going on. That cannot be said for any other camera in this price range as far as i know.

I admit I'm biased towards 720 but I do for good reason and not "just because."

In HD broadcast, I've seen football games on CBS which is 1080i. I've also seen them on ABC (superbowl) Because of the 720P image and 60p that is ABC's HD Format, the superbowl looked awesome! Even with fast moving action, the picture quality is maintained. What does it do on CBS with 1080i? A mess of pixelated garbage.

I'd rather have a stable picture personally. :)

But thats just me.
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Old April 14th, 2006, 11:49 AM   #8
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Well yes and no ;)

If you need 1080i then the HD100 shouldn't even be in the discussion. If we want to talk about a level playing field (720p) then I give the edge to the HD100.

The Canon at 24F degrades verticle resolution and shows aliasing at around 540 lines. (Per tests I've read). Now I'm not saying that the image doesn't look good or that it can't beat the HD100 in some areas. I'm just saying that when strictly talking about trying to shoot Green Screen to tape that the HD100 will give you a better key.

If we go out uncompressed from both cameras to some other device then it's a toss up. Canon might have an edge? However, going out uncompressed as interlaced or progressive, I'll take the progressive. We also forget that the HD100 can go out uncompressed at 4:2:2.

If you have DV Magazine there is a recent article about progressive images doing better than interlace captured footage with compositing. This thread is not about which camera is the better camera over all. It was regarding trying to shoot footage that must be keyed. Considering that I spent years as a 3D Supervisor and Digital Compositor for a Matte Painting house in Hollywood, I can tell you that I've seen my share of the best and worse shot green/bluee screen footage. Often times we had to shoot small inserts on video to blend with the actual film elements and interlace was always a problem. I've tried some HD100 green screen material and was very impressed of what I could pull with Ultimatte. They were not 2K or 4K Cineon files but still impressive.

Edit: I found that sample: http://i.cmpnet.com/dv/magazine/2006...605hd10001.jpg
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Old April 14th, 2006, 01:43 PM   #9
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If you read the latest DV.com review of the HD100 they mention in their bottom line "True 24p without resolution loss: great for film-outs".

http://www.dv.com/reviews/reviews_it...leId=185301200
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Old April 14th, 2006, 03:05 PM   #10
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Thank you very much Tim. Actually I was looking for this article as I posted before and you gave it to me.

Quote:
Originally Posted by Tim Holtermann
Well if you read the latest DV.com review of the HD100 they mention in their bottom line "True 24p without resolution loss: great for film-outs".
No doubts! But 1080/24F wouldn't be as well?* Both can be equally true.

But my concern carries on. About the jpg link, I'm thinking that it is Z1U footage and not the sharper Canon XL-H1. I'm not sure if you know this: http://www.eidomedia.com/test/out_test.htm

As matter of fact, I'd like to have the same test between XL-H1 at 24F & HD100 at 24P. Also because 2.35 wide it will be a possibility also to my work. Though I prefer the JVC film-like, I'm asking if the Canon isn't it higher res even at 24F. 1080/24F wouldn't be higher than 1080/24P?

* Or even better yet?
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Old April 14th, 2006, 03:43 PM   #11
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Aliasing

One of the things that I noticed in looking at my GS footage upclose is that there is quite a bit of aliasing along the shoulders of my talking head. Same thing for a lot of the hair edge. It can be fixed by blurring the matte but I rather fix it in the camera.
I'm not sure why this is happening but it might be related to the sharpening settings. I currently have my HD100 set to "MIN" but there might be a better solution by adjusting the horizontal sharpening. Unless, of course, the camera was doing antialiasing by using the green background and, when removing the green portion of it, the result is aliased pixels.

Anybody has noticed this? Any suggestion?

TIA
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Old April 14th, 2006, 03:49 PM   #12
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According to tests done with the Canon, when shooting 1080i at 24f you get far less resolution. (500lines?). Ouch. What ever magic mojo they are doing to get their 24f it's hurting the image. Ref: http://www.dv.com/news/news_item.jht...leId=184429497

Think about this - The Varicam is used on features (film out) and it records less resolution to tape than the HD100. This HD100 chip captures at true 1280x720 progressive and records true 1280x720 to tape.
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Old April 14th, 2006, 04:02 PM   #13
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Quote:
Originally Posted by Leuname Ereh
I already don't understand anything!

HD100 isn't it lower res (1280x720) than XL-H1 even at 24F (1440x1080 -> 1920x1080)?
The XL-H1 loses anywhere from 1/3 to 1/2 (depending on testing method/conditions) of its resolution in 24f mode. You can't deinterlace footage, especially on the fly with an on-camera chip, without throwing a good deal of your vertical resolution away.

Adam Wilt's 4 camera comparison over at DV.com had the XL-H1 showing a measurable resolution of 550 lines in 24f mode, while the HD100 measured at almost 700. Adam would probably be the first to tell you not to take those numbers as absolute gospel- but they do illustrate that there's more to consider than just the resolution being recorded to tape. For instance, the Sony FX and Z1 are both 1080i cameras- and they have a noticeably lower measurable res than the HD100.
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Old April 14th, 2006, 04:40 PM   #14
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Quote:
Originally Posted by Jake Strickbine
Adam Wilt's 4 camera comparison over at DV.com had the XL-H1 showing a measurable resolution of 550 lines in 24f mode, while the HD100 measured at almost 700. Adam would probably be the first to tell you not to take those numbers as absolute gospel- but they do illustrate that there's more to consider than just the resolution being recorded to tape. For instance, the Sony FX and Z1 are both 1080i cameras- and they have a noticeably lower measurable res than the HD100.
I also tested the XLH1 in 24F mode and got the same vertical resolution results - under 600 lines. The horizontal resolution seemed to come in between 700 and 800 lines.

The results from the Texas Shootout (when published) will probably confirm this finding. I like that Nate has said there is no one true winner, but in my personal opinion, when it comes to green screen I wouldn't use the XLH1 in 24F mode for greenscreen work to be posted in HD.
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Old April 14th, 2006, 09:40 PM   #15
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Well even though the Canon is only resolving around 540 line all of those lines have chroma detail. In 4:2:0 both the horizontal and vertical get cut in half. This means 720x540 of chroma.

While the JVC may be resolving more detail the Canon has many more chroma pixels. The JVC only has 640x360 chroma pixels. You can have all of the detail in the world but when keying if the chroma edges are dull your keyed edges will be dull. both cameras will of course have the same 2x2 pixel blocks but the Canon will be have more detail in chroma.

In 24F and 30F the Canon uses the same progresive encoding method as the JVC for perfect 2x2 chroam blocks. With 60i however it will have the crappy chroma of interlaced HDV.


Now if you plan on using component or SDI for capture well then JVC should have the edge because then it would get 640x720 while the Canon because it is only getting one field would still be at 720x540.

Of course all of this is just in theory. While one would think the SDI is still only 540 lines I have seen some 24F SDI greenscreen footage that had a heck of a lot more chroma detail than 540 lines.

Anyway I am actually a big fan of the JVC I just thought I wold bring up this one point about the chroma.
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