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REVISED: Calculated Estimate of HVX200 CCD Resolution
A post in another thread asked:
"I was a bit confused about the resolution test. What do the many question marks in the HVX200 column mean? 1080i AND 720p camera resolutions at 24F: TVL/ph (H rez.) TVL (V rez.) 550? 540? My initial response: The HVX200 resolution seems very low. It's a shame if these numbers are accurate." -------- For past work, I've built a math model that estimates measured resolution given CCD resolution. It incorporates: an Interlace Factor, a Kell Factor, a Green-shift Factor, and a De-interlacer Factor. For existing HD cameras -- including those in the test except the HVX200 -- the total (horizontal and vertical) AVERAGE error of my model's estimates is zero lines. (The vertical average error is zero. The horizontal average error is zero.) So I plugged in the measured HX200 resolution numbers -- assuming they were valid -- and solved for the minimum error. The solution indicated the three CCDs were 1080 by 812. Hmmm! 1080x810 is a perfect 4:3 ratio. Putting in 1080x810 yielded a total (horizontal and vertical) average error, for ALL HD cameras, of -9-lines. This estimate did not use Green-shift which it is rumored the HVX200 chips use. So next I plugged in 960x720 (which I have always believed is the CCDs resolution) and turned ON Vertical and Horizontal Green-shift, and the total (horizontal and vertical) average error for ALL HD cameras was +6-lines. This model assumed 720p and 1080 24F is obtained by de-interlacing the chips' output. If this is correct -- there should be little difference in sensitivity between 720p/1080f24 and 1080i modes because the chips are always running in interlace mode. Two other CCD resolutions have been proposed: 960x576 and 960x480. These is are widescreen PAL or NTSC CCD's resolutions. Running the model with these resolutions, and assuming the CCDs could run in both interlace and progressive modes, indicated the 960x480 option was a possible option. It yielded a total (horizontal and vertical) average error of 2-lines. If this option is valid, there should be a sensitivity difference between progressive and interlace modes -- with 720p24/1080f24 being 1-stop less sensitive. The Vertical resolutions estimated by the models: INTERLACED 960x720 CCDs (720p and 1080 24F mode) = 567 TVL SWITCHABLE 960x480 CCDs (720p and 1080 24F mode) = 540 TVL MEASURED (720p) = 540 TVL Given that my model predicts Vertical resolution across all HD cameras (without the HVX200) with ZERO error, my model's estimate should be very close. The obvious best match, to the measured vertical resolution, is the SWITCHABLE 960x480 CCDs model. HOWEVER: Using 960x480, the estimate for 1080i60 vertical resolution is only 378-lines which is way too low. (This mode was not tested!) Using 960x576 increases estimated vertical resolution for 1080i60 to 454-lines which is better, but still low. But, with 960x576 the 1080 24F and 720p vertical resolution estimates are too high at 648-lines. For this reason, neither of these options seem valid to me. -------------------- Now to your question about the question marks. I think the reason why the measures were so hard to get is that Panasonic is not using a typical design. I believe that using INTERLACED 960x720 CCDs running with both vertical and horizontal Green-shift AND that significantly under-sample 1080 AND that de-interlace for 720p and 1080 24F -- output resolution patterns that are quite unusual looking. Hence the question marks. -------- Five more points: 1) Although not tested, the INTERLACED 960x720 CCDs option estimates that in 1080i60 mode (not tested) the resolution measures will be the same as when running at 1080 24F. This result support the INTERLACED 960x720 CCDs option. 2) Panasonic does not have SSE so we can speculate they avoided this by using a much lower rez. CCD than did JVC. Both options use a lower rez. than the JVC pixels. 3) The NTSC 960x480 CCDs would make the HVX200 more sensitive than any of the other low-cost HD camcorders. And, that's exactly what the test found. However, because the 960x720 is also lower resolution than the other low-cost HD camcorders, one would expect it to also be more sensitive. Both options are supported by the data. 4) Panasonic refuses to give us the CCD spec. and were they to be using PAL or NTSC CCDs one can see why they would really not want that fact known. This favors the SWITCHABLE 960x576/480 CCDs options. Although, because of the flack Sony got for not using HD resolution CCDs, Panasonic may have wanted to hide even 960x720 since it is not the 1280x720 resolution offered by JVC. 5) The sensitivity in 720p verses 1080i will tell us which option is correct -- not tested, unfortunately! |
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First, it's pretty well accepted that the EIA resolution charts don't hold up all that well with resolutions in excess of about 800 to 900 lines. Even with cameras like the Viper or F950U CineAlta with their full 1920x1080 censors. So, resolution chart tests with these new 1/3" HD cameras are a little sketchy... Looking at the limited res chart tests done with the HVX and XLH1, we seem to be seeing 650 to 700 lines out of the HVX and about 750 to 800 lines out of the XLH1. But looking at footage from both cameras, especially the HVX footage, I don't think those res chart tests are telling the whole truth - nowhere close. It's difficult to judge CCD resolution from this when there are obviously limiting factors with the glass and with the chart and test methods. We have other ways to determine CCD resolution and how it may be sampled. One approach may be simply looking at the specs we do know and trying to match that up with available CCD components. We also know that the HVX CCD block does in fact scan progressively all the way up to 60Hz. It is also a native 16:9 CCD. I suppose we could start cross referencing that and other little tidbits along with known component suppliers to Panasonic and see what we come up with. This is also speculation on my part, but I am of the opinion that the CCD block is a 16:9 1024x768 imager. The pixel shift would effectively allow for a scanning area of up to 1536x1152. Which is a very nice fit for interpolating a 960x720 (DVCPRO 720p) or 1280x1080 (DVCPRO 1080) image. It is possible that the censor is 960x720. That would in fact give them an equivalent scanning area of 1440x1080. But I would doubt that the censor is any lower than 960x720 and I think the 1024x768 is far more likely. Higher resolutions, like 1280x720, are also highly unlikely. |
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I'm pretty positive the ccds based on the reported behavior of the camera's in various tests and fact that DVCPRO HD media format captures at 960x720. It only makes sense that the CCDs are that size.
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On an EIA chart I could make a case for 730 lines vertical, although I'd probably be more comfortable calling it 670.
http://www.fiftv.com/HVX200/1956-Chart-Extraction-1.jpg Steve, the HVX doesn't work like the DVX. There is no interlace scanning ever. It's always progressive. On the DVX, going into interlace gains you a full stop of sensitivity. On the HVX it's identical for both 720/60p and 1080/60i -- interlace and progressive sensitivity are identical. And, in fact, it's a little FASTER at 24P and 30P than it is at 60P or 60i -- most likely due to the impossibility of executing a 60fps refresh rate at a full 1/60 shutter speed. In the FILM CAM mode it actually limits the shutter to 350 degrees so there's a little bit of free time to dump the sensor's charge. I believe that is the reason the full 60hz modes are a little bit slower than the others. Interlace is created from the internal 1080/60p scan. We don't know what the pixel count is, but we have been told that it scans the CCD at 1080/60p (or whatever your frame rate is), and then downconverts that scan to 720p, slices and interleaves it for 60i, etc. |
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Steve,
For us non-rocket scientists.....are you saying the HVX might be scanning interlaced? Give us your hypothesis using a little street talk with a touch of slang. *smile* - ShannonRawls.com |
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Barry, I've seen no information from Panasonic that describes anything about the way the HVX works -- in particular any notion it has 1080p chips. All we have is the resolution data from the tests. Thank you for the information that 720/60p and 1080/60i have equal sensitivity. That is the data I needed to reject the 960x576/960x480 options. So that supports the 960x720 resolution option. Curious if you have a resolution number for 1080i60. |
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That step was necessary to get ALL the constants correct before running the model in reverse with the HVX200 measurements. It even makes it possible for me to test the idea the HVX has 1080p chips. Which I'll do -- but given JVC's experience with 720p chips running too hot that seems very unlikely. Of course, Panasonic could be running it in dual 540-line mode and doing a better job of matching both halves. And, you have to ask why Panasonic would hide a "feature" like 1080p. ESTIMATE: Using 960x1080p CCDs (with H. Green shift) or 1080x1080 (without H. Green-shift), the model's error is a whopping 74-lines! If the CCDs were 1080p, the model predicts V. rez. in 720p and 108024F to be 756 TVL. Since they measure at 540-lines it seems very unlikely 1080p CCDs are being used. I'm now wondering if the question marks indicate a behind the scenes disagreement because the data measured clearly do not match the "concept" of 1080p CCDs. Moreover, the EIA 1956 chart is not the correct chart for HD -- see Adam's dv.com comments. So I'll stick with the data. |
This might be a totally nuts idea but I think there's another way to determine the CCD size, use the dark current noise. With no light hitting the CCDs each pixel of noise is one element firing by itself, stack enough frames and look at each channel should reveal the number of elements generating the noise and hence the true CCD resolution, probably best done by capturing 4:4:4.
Here's a question that I don't quite get. For any camera using pixel shifting just how much advantage is there in 4:2:2 sampling over 4:2:0, if the pixels aren't coplanar isn't the result of recording 4:2:2 going to be about the same as interpolating 4:2:0 to 4:2:2? |
Steve...
Can you share your model with us, or is it proprietary? At least, tell us what you can about it...? |
I believe it was confirmed by Panny that the HVX would record 1080p... I never saw anything that said the chips were NATIVE 1080P... Barry could confirm I am sure. 960X720 seems likely to me, I edit my Varicam footage in that and it looks great...
ash =o) |
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1/3" 16:9 native high-sensitivity progressive 3-CCD with 1080/60p scanning Pretty clear to me. So obviously it's a Progressive chip like Barry says. We just don't know if its 1080 horizontal or verticle. If anything else was discovered....that would be catastrophicly bad for Panasonic. Quote:
But again, I'm not sure. Barry? DSE?? Chris?? - ShannonRawls.com |
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Jan went on the record as saying that the camera did not have 960X720 CCDs or 960X540 CCDs.
It could be like 960X719, though.... Personally, I'm betting it's something way lower, like 720X540 with lots of pixel shifting. We're seeing similar amounts of noise to the dvx at a similar sensetivity (in progressive mode) so I think it's got a similar pixel density, just with intense pixel shifting and true 16X9 chips. |
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1) Believe this statement means Panasonic is using CCDs that have 1080 rows and are always progressively scanned at 60Hz -- and then deal with the fact that such advanced CCDs deliver measurably less resolution than a 2 year old JVC single CCD (with only 659 rows) HD10. Can anyone really believe Panasonic would progressive capture 1080 rows and discard half the information? If this is true, Panasonic has messed-up its implementation beyond belief. 2) Or, you decide that someone in marketing put together a sentence that tries to describe two things at once: 1080-line output (for 1080i and 1080 at 24F) AS WELL AS 720 progressive at 60Hz. Which is why Chris says "I've noticed numerous occasions where Panasonic went out of their way to state that this camera did have 1080p." Yes, it RECORDS 1080p24. It also RECORDS 720p60. That says little about the CCD. Marketing's single sentence was an attempt to describe the CCDs without specifying their resolution. So which is it? A massive screw-up by Panasonic R&D or bad turn-of-phrase by Panasonic Marketing? There is no reason to believe Adam got valid measures of all the cameras except the Panasonic. And, I've got zero reason to believe my model that works with ALL the other HD cameras doesn't work with the Panasonic. It all suggests to me Panasonic knew review measurements were going to be bad -- and felt giving out the real CCD specification would only add fuel to the fire. I think it's now becoming obvious that hiding information from your potential customers and the press is a bad idea. Unfortunately, Panasonic is not alone. Sony tried to stonewall a room full of reporters about CF24 after we had all seen how bad it looked; JVC took a month to explain and "fix" SSE; and Canon still won't explain 24F -- like I haven't plugged their test data into my model to "see" how it works. |
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Steve, where is this documented? I've heard later model HD100 have less SSE problem, but it still exsists, especially under gain. Not that I plan on using gain :) |
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I just can't get over how crisp the images are from this camera! http://www.reel-stream.com/magik_tes....tif?type(tiff) |
Hi Steve... is that a "no" on sharing your model?
Without knowing more, it's just throwing around irrelevant data and hiding realities much like you accuse Panasonic of doing. I can easily create a model that would fit six things and be completely inappropriate for a seventh... especially if the model is created through some kind of fitting to the data of the first six. C'mon, throw us at least the parameters you're playing with! |
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Like the data from the DV magazine tests, you can do whatever you like with the information from the model. |
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Ya know, I've been reading various websites here and there on the net talking about that outstanding DV.com report of Adam's. Sadly, all kinds SUPER FUD is being born. I am really really really really really really trying very very very very hard to restrain myself and not BLOW UP. *counting to 10*, But I am being a better internet person today. I promised Chris Hurd I will conduct myself more appropiately, and I found the best way to do it is to not say anything at all. I don't know how to sugar-coat my words and make people feel all warm and fuzzy. I can hold my own when it comes to arguing a point or discussing camera gear and being REAL about it, but I seem to get banned whenever I make sense and rage against the machine. Anyhow, I'm glad you said that statement. Lord knows I wanted to.....just can't. Either way, Steve, I do believe in your model and I do believe your PhD means something (i'm a college graduate, so I have a huge respect for doctors), so I doubt you're being unfair with your proprietary calculations. I also know you have a bias for JVC and will say stuff to make them look good *smile*, but that doesn't change your scientifc data about things and how cool of a guy you are! *smile* - ShannonRawls.com |
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I also understand that there are lots of reasons for keeping models proprietary, and don't blame steve for that. But at the same time (and I'm sure he unserstands this), without details, it boils down to trust. Which is fine, and par for the internet course. -Barry |
I guess it is all semantics... I mean if Panny says the CCDs scan at 1080p... could it go thru a process to get there? I dunno... they have released so few details about the CCD.
ash =o) |
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By the way, what happened to just looking at the image? Steve Mullen is quite right when he points out that every manufacturer seemingly has something to hide. This is not a Panasonic issue nor Canon, Sony or JVC. It is industry wide. Unfortunately. |
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The Canon USA folks I talked with were so unhappy at having to say "nothing" about 24F because Japan Inc. said "don't talk." I really doubt Jan, or her husband Phil, who like Jan is truly brilliant -- don't want to sit down and explain a product. And, JVC allowed things to get way out of hand before publishing something about SSE. It would be so much smarter if ALL these companies would take the lead and not make us "drag it out of them." Cause we will! :) By the way, I really appreciate Shannon's directness. |
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I posted an EIA1956 extraction, you can see what you think about the measured res from that. I also don't think the EIA is the right chart to use with a 16:9 camera, but so many people seem to be posting them, and Juan Pertierr of Reel-Stream asked for it, so that's why I put it out there. We will be re-testing Jay's camera against mine to see what the deal is; an argument could be made for mine showing 670+, so we'll test it against Jay's (the one from the six-cam test) and see how they perform against each other. That should at least confirm or rule out the concept of a spurious sample. |
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I gotta ask, does anyone here know how a CCD works?
ALL CCDs transfer the charge from the photodiodes to the CCDs an entire frame at a time. The stored charge on the CCDs can then be clocked out in quite a number of ways, has zip to with it being 24p or 50i. One can have a CCD with 4 taps feeding 4 A/D converters or in the case of the HD100, I suspect two A/D converters, the big problem is making 100% certain that the A/D are precisely matched else the SSE problem. So technically one can scan a CCD at 48Hz and still produce an exact 24fps progressive sequence. Whatever the photodiodes have transferred to the CCDs remains until a new transfer takes place. In an interlace system, the whole frame is transferred to the CCDs but only every second line is scanned and then another frame is transferred and the alternate lines are scanned. If you don't transfer the frame a second time, the result is 24PsF which will yield 24p. All that aside there's gotta be a dead simple way to resolve the CCD resolution issue for any camera. Open the thing up and stick a logic analyser in there to count how many times the A/D converter(s) are being clocked per frame, that'll give the total pixel count, looking at the row and column clocks will also reveal the horizontal and vertical resolution. A way more accurate approach than relying on resolution charts, you remove the lens issue and the human factor. You'll probably remove your warranty too. |
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This question of CCD resolution will probably remain unsolved until Panny finally comes forth with the information (doubtful) or until someone has a junk HVX to take apart and they put the CCD under a magnifying glass and count the photosites. ...1024x768. That's still my guess. There are a few CCDs on the market with native 16:9 and 1024x768 resolution that could meet the requirements of the HVX. But Panny may be using a custom CCD block too. Jan has said the resolution is most certainly not 960x720... It also looks pretty obvious that the vertical resolution is AT LEAST 720 as some res charts can be shot showing 700+ lines. |
Desktop scanners advertise the same way. On the box it's 2400 x 2400 resolution but the reality is that it's 600 x 600 optical resolution. Nevertheless, it's listed as 2400 x 2400 scan.
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Sage words from the Hurdster. This does get nearly absurd at times. Shooting side by side on set today with the Canon and the HD100 and looking at the HD footage from the HVX...what's the big whoop. They literally all look great - just different flavors. Now a meaningful discussion would seem to be more on the aesthetic differences (without scientific reverse engineering as to how they get their looks <g>. For instance as a guy who really likes and has had great success with the Canon in each generation, I really didn't think I would be comfortable with the JVC (just stupid presumptions on my part). However, using a TV shoot today to shoot the same talent on the same set with the Canon followed by putting the HD100 on the sticks there was no question that there is a substantially "different" look to these cameras using similar settings. All I can say is the HD100 is smoother in skin tones and overall image and as much as I've loved the Canon, the JVC is, to me, a much more filmic tool. It feels, looks, handles and produces images that look remarkably like 16mm film. Not saying that the JVC is better, but for a straight "film" camera, this might be the most realistic tool below the Varicam level. |
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However, I did try my model with 1080-row and 1080-column chips running PROGRESSIVELY. The "1080-column chips running progressively" option came close enough that I tuned my model to get zero error over all the cameras -- plus the 1080i60 mode of the HVX200 and the Sony in CF30 mode. (The latter I hadn't included before.) This new model estimates ALL cameras in ALL modes with ZERO total average error. When I enabled both Horizontal and Vertical Green-shift -- as I have heard the HVX200 uses Green-shift -- the exact CCD resolution was 960x810. Of course, without Green-shift, CCD resolutions increases. I was able to get the model to also work perfectly with 1080x810 (1.33:1) CCDs. Note that this finding is important because this model could be described as "1080 at up to 60p." So the most likely resolution is 1080x810 running progressively. My model estimates H.rez. will be 561 TVL/ph and V. rez. at 536 TVL. The actual measures were 550 and 540. Lastly, I don't think Panasonic blew-it by using lower than usual resolution CCDs. There are two VERY good reasons for doing so: 1) Much better sensitivity -- which the test confirmed. 2) No hot CCDs so no need for clocking each half separately so no SSE. If this is all true -- there was never any reason to hide the CCD spec. Just provide the market with an explanation! |
A new wrinkle is that the rez chart was shot at F5.6. I didn't know this either. They need to test it around F2.8 and see the results. Still if the rez dumps to 550 lines at F5.6, its not a good showing.
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Rez Charts, Smez Charts. People are just fanatical! Who says it was at f5.6? Was it a guess, or was it rock solid assurity? Focal lengths, positions of the camera, the girl moved, noise here, no noise there, what was the other camer settings? maybe the Canon was at f9?? who knows? skin tones were good, skin tones were bad, interlaced scanning, progressive scanning, blown highlights, SSE, no details in the shadows, chromatic abberations, it look slike a chainsaw, it looks like a football, it looks likea bazooka, blah blah blah. And now.....it's all about the MOJO. lolol LMAO LOLOLOLOLOLOL hahahahaha. My god. Now it's the offical "Austin Powers" Camera. *smile*
If you really are on the fence.....THEN WAIT FOR THE TEXAS SHOOTOUT @ THE ALAMO! *smile* This test should be objective, documented correctly, in an ideal location and under no time constraints or pressure. Cameras will be set correctly and the settings will be recorded by a dedicated person. And honestly people, whatever the test results come out to be.....you already know what you want. So just go buy it. I wonder.....how many people actually use these cameras professionally outside? I mean like really outside the house on real gigs with real people and real money being spent. People like Barry Green & DSE & Heath & Nick & Chris & Jon Fordham & Steve & Barlow do come here and report because they are Nerds. But Nerds are cool! why? because Nerds get paid, Geeks do it for free! *smile* These guys aren't Geeks. They actually leave their houses and get paid using this daily! Stop being geeked out over these tests and go buy a camera already. 1 month down 11 to go. You're running out of time in 2006. How many things did you do in the month of January while you were waddling around on the internet waiting for 10 second clips from Germany and test charts from Japan? Don't be an "Internet DP". Think about it....it's just a camcorder. And it costs less then that 42" plasma HDTV you bought 3 years ago! I bet you didn't geek out over that waiting for tests and argue with people and lose friends over that HDTV before you bought it! So why now over a camcorder that costs less? My wife just bought an all electric automobile (GEM e4) to drive around on the weekends for $11k grand. You think she waited on test charts & argued on the internet with people who owned other type electric cars? LOL. So why now over a camcorder that costs less? I hope you get my point friends. We should never HATE or DISLIKE eachother here. Especially over these dag-on camcorders. It reminds me too much of the pitfalls of human nature. We should all be COOL and FRIENDS and work TOGETHER and combine forces.....we can all get rich(er) that way! Look at it this way.... If you buy an HVX200...YOU WILL NOT RETURN IT! That camera is bad-ass!!! The image is cold-blooded, and for $6k, you will be OVERLY pleased. If you love the DVX.....it's a no-brainer. So forget the res charts and all that. It's meaningless. - ShannonRawls.com |
We're just guys talking about cameras here......
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