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More HVX200 info
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It’s an analogue device that’s also a sampling based system, in that it has discrete photosites. It’s not analogue in the sense of a tube camera, or digital in the sense of CMOS – somewhere inbetween….
Graeme
– http://www.nattress.com – Film Effects and Standards Conversion for FCP
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i allways thought there were allways pixel shift in CCD to avoid vertical stripes
but it is not ala sony hdvjean-yves le moine
temps r
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[Rodrigo Lizana] “One thing I noticed about the specs is the lack of a 1/48 shutter speed (180 degress) and a 1080p recording option.
It does have 1/48, and it does record 1080/24p and 1080/30p. It just records them within a 60i data stream, exactly like the DVX, XL2, SPX, and SDX all do.—————–
Get the most from your DVX camera. The DVX Book and DVX DVD are now available at https://www.dvxuser.com/articles/dvxbook/ and at Amazon (https://www.fiftv.com/db) -
[Brian SaenzDeViteri] “While on this topic, what is the image size and pixel aspect ratio of a 720p recording and 1080i (and 1080p) recording on P2 cards?”
720p: 960x720x1.333 PAR, up to 59.94 progressive frames per second, with 4:2:2 color sampling (chroma at 480×720).1080/60i: 1280x1080x1.500 PAR, at 59.94 fields per second, 4:2:2 color sampling (chroma 640×1080).
1080/50i: 1440x1080x1.333 PAR, at 50.000 fields per second, 4:2:2 color (chroma 720×1080).
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Get the most from your DVX camera. The DVX Book and DVX DVD are now available at https://www.dvxuser.com/articles/dvxbook/ and at Amazon (https://www.fiftv.com/db) -
[Lawrence Bansbach] “Jan has repeatedly said that the HVX’s CCDs will use pixel shift.”
Sorry, I don’t read DVXuser.
So there must horizontal pixel shift, because there is no vertical pixel shift, because the chips are “native progressive 1080/60p scan”.[Lawrence Bansbach] “”Without pixel shift/spatial offset, you would have vertical stripes in the pictures, which once the light became low you would see.””
Could somebody explain what this means?
Every ccd and cmos have gaps between photosensitive area of the pixels.
This does not mean that those gaps are somehow sampled into produced picture.
If you like, you can think that the produced picture has “wider” pixels than the ccd, that overlaps the gaps.
So if camera would have full resolution chips (same amount of pixels on a chip than in produced picture), there’s no need or use or benefit from pixel shifting.Since hvx200 does use horizontal pixel shifting and it produces a picture with max 1280 horizontal pixels, there must be fewer horizontal pixels on a ccd chip.
So, I guess it has 960×1080 chips, same as fx1/z1, so it also can’t be much more sensitive than those sony hdv’s. -
Toke Lahti:
So if camera would have full resolution chips (same amount of pixels on a chip than in produced picture), there’s no need or use or benefit from pixel shifting.Actually in a 1/3″ CCD if you had a pixel for pixel match on the CCD to the format, there would be so much aliasing and noise you would have to filter it all off. And of course the lens couldn’t handle it either, and low light would suffer and I don’t even want to talk about dynamic range. The chip is an analog device in CCDs, CMOS is a different technology altogether and is sort of a half breed between as each pixel sends out info, which is why a dead pixel on a CMOS is not a good thing.
And BTW, most CCD cameras that I am aware of use some form of offset technology. Most just don’t talk about it.
>Since hvx200 does use horizontal pixel shifting and it produces a picture with max 1280 horizontal pixels, there must be fewer horizontal pixels on a ccd chip.
Well Toke, your inside info is not info. A subsample is just that a subsample and means very little to the outcome if indeed the playback is 1080 X 1920. Sub sampling is part of the compression scheme. If we take the picture of the Z1 and put it up against the HVX, we find that the two cameras are very comparable in resolution on a resolution chart. So how does that fit in with your theory here? Now I understand that you have not seen this for yourself but in time you will.
>So, I guess it has 960×1080 chips, same as fx1/z1, so it also can’t be much more sensitive than those sony hdv’s.
And frankly here you are again, the low light on the HVX is beter as is the dynamic range.
Best,
Jan
Jan Crittenden Livingston
Product Manager, DVCPRO, DVCPRO50, AG-DVX100
Panasonic Broadcast & TV Systems -
[Jan Crittenden Livingston] “And BTW, most CCD cameras that I am aware of use some form of offset technology. Most just don’t talk about it.”
Jan, could you enlighten me, why would full res ccd cam (like 2/3″ hdcam) use offset?
Isn’t it better that you get all color primary subsamples registered at the same spot, both in the ccd block and eg. in the hd-sdi feed?
Why would you displace these subpixels when there is no scaling? -
[toke lahti] “Jan, could you enlighten me, why would full res ccd cam (like 2/3″ hdcam) use offset?”
Actually Toke that particular camera does not. Note that I said most, and the 2/3 HD cameras are different, but many of the SD cameras do and probably most of the 1/3″ cameras do.
[toke lahti] “Isn’t it better that you get all color primary subsamples registered at the same spot, both in the ccd block and eg. in the hd-sdi feed?”
See this is where you keep thinking that the signal coming from the CCD is a dgitial signal. It isn’t. It is light transformed to energy, which eventually is transformed to digital after the Black Shading and White Shading circuitry.
[toke lahti] “Why would you displace these subpixels when there is no scaling? “
Because this is not how it works. A spatial offset takes the red and blue chips and covers the non-photosensitive areas of the green chip. This allows a chip set to produce more resolution than what a single chip could do all on its own. These signals make an additive gain to the overall performance of the camera.
An example would be to look at the XL-1 camera. It worked with a CCD assembly that had spatial offset. There are 270,000 pixels in that chip, yet it had better resolution than the competive cameras that had 310,000. How did they do that? With spatial offset. It is not scaling, it is not cheating, it is engineering. It is taking advantage of the techology and the fact that it is an analog signal, it is not a pixel for pixel match up on the recording, it is an analog signal.
Hope that helps,
Jan
Jan Crittenden Livingston
Product Manager, DVCPRO, DVCPRO50, AG-DVX100
Panasonic Broadcast & TV Systems -
[Jan Crittenden Livingston] “[toke lahti] “Isn’t it better that you get all color primary subsamples registered at the same spot, both in the ccd block and eg. in the hd-sdi feed?”
See this is where you keep thinking that the signal coming from the CCD is a dgitial signal.”
I’m not thinking that ccd is digital device. But analog data gets converted to digital and then it’s naturally better that all primaries color samples are taken from the same spot in the picture.
[Jan Crittenden Livingston] “Because this is not how it works. A spatial offset takes the red and blue chips and covers the non-photosensitive areas of the green chip. This allows a chip set to produce more resolution than what a single chip could do all on its own. These signals make an additive gain to the overall performance of the camera.”
I know what spatial offset is.
And it really doesn’t matter at what stage you do the ad-conversion. You can use spatial offset with 3ccd or 3cmos camerablocks.
Idea is based on a fact that analog rgb-data from ccd’s gets digitized and then converted to _component_ format, where luminance has more resolution than chrominance components.You don’t get any more resolution with spatial offset to the rgb-stage, but since the luminance signal is calculated from all of these rgb-colors, you get the benefit in resolution after YCbCr-conversion.
So you do get some info from other chip’s non-sensitive area to produce a higher resolution luminance data.
Calculating this luminance data needs averaging rgb-data, interpolating and usually, yes, scaling.[Jan Crittenden Livingston] “With spatial offset. It is not scaling, it is not cheating, it is engineering.”
This is where you go wrong. Spatial offset uses fundamentally scaling. It is same thing that happens in one-ccd/cmos digital still cameras. If camera uses offset in all 3 chips, then you get a raw picture which has double vert&horz resolution and all samples next to each other, side by side. From this image YCbCr-signal’s components are calculated with interpolation and scaling.
If you would like to get a rgb-picture as an end result, like with digital cinema cameras (viper/hdcam-sr), there would be no use for offsetting the chips, because you would just have to “onset” the samples back on top of each other. Moving samples (=pixels) spatially back and forth always blurs them a bit because all the roundings that has to be done in calculations. That’s why you’d want to get the rgb-pixels on top of each other at the first place, in the ccd’s.
And again there’s also no benefit for spatial offset with full resolution chips, because you already have full rez rgb-components, you can’t use more resolution to the YCbCr-components. Because 2/3″ ccd’s are usually full rez chips they don’t use spatiall offset.
Then again 1/3″ chips are so small that for them it is better to use non-full rez ccd’s to get larger area per pixel in the chip so the chip remains more sensitive. And that’s why I’m a bit dissapointed if hvx200 does not use vertical pixel shifting. My claim is that with 960×720 chips with vert&horz spatial offset, you could get as sharp pictures than with 960×1080 chips with only horz spatial offset. Previous just has more sensitivity.
Only logical explanation that I can come up on why no vert pixel shift is that it would be more difficult to use with interlaced picture. So interlacing, the great ghost of the analog age, still haunts us…
I think that as long as we are recoring in YCbCr-format, we could always benefit from spatial offset and it would be good idea to Panny to build next varicam with vert&horz pixel shifting 1280×720 chips to produce great 1080p-picture.
Maybe in the distant future, when everything has too much bandwidth and storage space all recoring change to rgb…
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Toke:This is where you go wrong. Spatial offset uses fundamentally scaling.
I have a feeling this is another one of those discussions that we will never come to agree as frankly it is not scaling. It is using information that is there and using all of it without making the pixels so small that it suffers in low light or has no dynamic range.
>If you would like to get a rgb-picture as an end result, like with digital cinema cameras (viper/hdcam-sr),
And we would be using a much larger chip set and it would be a completely different camera then, wouldn’t it? In working with the camera we are bringing to the market, one has to engineer to get the best out of the parameters given, 1/3″ chip set, HD capable lens and prism, DVCPRO HD recording, and under $10,000. Big diff from a viper or HDCAM SR or VariCam for that matter.
>And again there’s also no benefit for spatial offset with full resolution chips, because you already have full rez rgb-components, you can’t use more resolution to the YCbCr-components. Because 2/3″ ccd’s are usually full rez chips they don’t use spatiall offset.
Actually in Standard Def 2/3″ cameras it is used, which is why specs for them offer higher res off the camera head than what can be recorded as well.
>Then again 1/3″ chips are so small that for them it is better to use non-full rez ccd’s to get larger area per pixel in the chip so the chip remains more sensitive. And that’s why I’m a bit dissapointed if hvx200 does not use vertical pixel shifting.
But then you do nothave to be disappointed because it does use horizontal and vertical spatial offset.
>Only logical explanation that I can come up on why no vert pixel shift is that it would be more difficult to use with interlaced picture. So interlacing, the great ghost of the analog age, still haunts us…
Since the initial capture from the chip set is a 1080p/60 capture and it downconverts or crossconverts from there, there is not the limitation that you suggest here.
>I think that as long as we are recoring in YCbCr-format, we could always benefit from spatial offset and it would be good idea to Panny to build next varicam with vert&horz pixel shifting 1280×720 chips to produce great 1080p-picture.
We already have a 1080i camera, this is the HDX400.
Best,
Jan
Jan Crittenden Livingston
Product Manager, DVCPRO, DVCPRO50, AG-DVX100
Panasonic Broadcast & TV Systems
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