CHROMA NOISE in HD10s

[Alex Raskin]

Yellow-green blocks are dancing on the skin or same-color surfaces like walls, when shot with JVC HD cams.

See examples here:

http://fancyflix.com/hd10.htm

I had nothing like that with my previous (non-HD) camera.

Is this a result of 1 CCD?

Is my camera malfunctioning?

Please opine based on your own experience with these HD cameras!

Thanks :)

[Brian Mitchell Warshawsky]

Is it possible all this chroma noise has more to due with the higher resolution than with the one ccd? Or perhaps the higher resolution combined with the MPEG compression.

Not currently owning this camera, the resolution in your shots looks amazing.

Does anyone have similar images comparing the edge enhancement between the two models?

Brian

[Paul Mogg]

I'm repeating this post from another thread as it asks the same question.


First of all you need to determine, is the chroma noise I see ALL in my orignal footage or is it being enhanced by my playback equipment?
While there is most definately significant chroma noise in the original footage shot on the HD10U, I have found that the software and hardware you play back through may enhance that chroma noise a great deal and give a very distorted impression of just how much chroma noise there actually is.
Worst are the software playback players like Elecard and VLAN. Next is NOT playing back on an HDTV (not a computer monitor) that is capable of 720p native format. There are very few HDTV's that are actually capable of this, most do upconverts to 1o80i or downconverts to 480i, on the fly, so I would say that MOST people are probably getting quite a distorted impression of how much chroma noise is actually there.
Though I am by no means reccomending a Monivision monitor to anyone, the amount of chroma noise I see in flat areas of color (where it is most obvious) is far less when viewed directly from the camera, or after transfer to D_VHS, on this 720p capable monitor.

I hope this helps.

[Daniel Broadway]

While I do not own that camera, I do know that 1CCD cameras have MUCH higher Chroma Noise than a 3CCD camera. I can't wait until they make a 3CCD HDV camera. It will be awesome.

[Eric Bilodeau]

My experience with the camera shows chroma noise is much as experienced with miniDV. Paul is also right about the display problem, be sure of your monitoring gear. Head to head, the DVX100, XL1s and HD10 displayed pretty much the same amount of chroma noise in the same shooting environnement, not exactly but even the miniDVs where not 100% equivalent. We have to understand that these videos are compressed by a very high though equivalent factor, miniDV (NTSC) is 4:1:1 (please don't tell me there is no chroma noise with 4:1:1 compression, I never shot with a miniDV camera that did not produce some chroma artefacts) and miniDV (Pal) and the HD10-HD1 use a 4:2:0 compression. Both mean that the chroma is reduced to 1 pixel out of 4 of the original image saturation, the 4:1:1 process is linear (on the same line thus a rectangle of 1X4) and 4:2:0 is bi-directional (horizontal and vertical for a square of 2X2, of course not very good in interlaced material but correct in progressive). Degradation in the chromatics (both red and blue) are equivalent in both types of compressions (of course the green channel is derived from the red and blue ones). A thourough examination of miniDV and HDV showed to us that high contrast rations (night clubs, night scenes, etc) are much better handled by the HD10 because of the fact that the compressor diminishes chroma in low light areas, thus significantly reducing chroma artefacting and improving the blacks over DV. The one CCD versus 3CCD thing here is very difficult to determine since this one CCD camera does not produce color in the same way as traditional 1CCDs. I suggest you read Steve Mullen's article on that subject following this link:

http://videosystems.primediabusiness.com/ar/video_ccd_counting_needed/index.htm

But let's be realistic, you have to be very efficient and to know the HD10 well to harness it's full potential. You need to understand light in a videographic way and to be open minded but some sequences (posted here) show very good examples of this camera's strenghts and weaknesses. Using the camera in full auto mode will give you worse results that auto mode with the VX2000, XL1s, DVX100 or PD150, in fact, in most cases it will give you crap.

Be open minded and this camera will give you outstanding results.

[Troy Lamont]

Eric,

Thanks, that was a very useful and to the point summarization.

Troy

[Ken Hodson]

Excellent post Eric.
The artifacts that are being spoken of I see with all video played back on my pc. I would add a salmon pink to the other two colours described. The more compressed the more the weird colours. It seems to be an element of software decoders and enhanced I find on ATi and NVidia cards. I also would like to know if you were using a software decoder Alex.
Ken

[Alex Raskin]

Ken, the color noise looks the same when played directly from the camera's Component ouput to HD monitor, or when viewed on PC via software player after the capture.

So this effect is *not* related to any PC-based software processing, but comes directly from the camera.

You wrote:
"I also would like to know if you were using a software decoder "

Please refer to the page in my original post - it describes in great detail how the snapshots were made.

"The artifacts that are being spoken of I see with all video played back on my pc"

I don't. My previous SD miniDV Sony VX2000 did not produce anything close to this chroma noise, and I pulled quite good blue screen works out of it with good lighting.

With HD10, chroma noise is so great, forget about the blue screen.

Also processing: try increasing saturation even slightly. You'll see weird lepro stains all over the place; the picture is falling apart instantly.

It was not so with VX2000.

Thus my question to people who *actually own/use* HD10: do you have the same issues or is my camera not adjusted properly?

[Ken Hodson]

"With HD10, chroma noise is so great, forget about the blue screen."
Well you have my attention. Even if you calculate in the increase of resolution?
My experience when getting that type of "noise" ,when using DV format is, when I gain-up in low light, or under expose in general. Or re-render to often.
The question is as follows:
Is the "croma noise" more or less than DV, given the increase in resolution? We have to talk apples to apples here. If we zoomed in the JVC-HD to SD resolution, what would be the croma noise diferance between itself and a quality DV cam?
Ken

[Stephen L. Minor]

I believe the color noise is in the camera not software decoders, crt tv'v have a little softer image than the pc so it tends to look better.

To compare this to DV color noise would have to be done by some level rating and compared percentage wise to the HD. With any footage it looks good on smaller levels. Watch a VHS tapes on a 9 inch tv it looks great, but put it on the 60 inch. big screen and whoaaaa crapola. The color might be better than dv but the size of the pic allows you to see more Flaws.

I agree, the chroma is way to poor for blue screen (unless you have some stellar equip. and skillz :-) I have shot EXT. night, EXT. day, flouresent, and stage spotlight. I'll post some frame grabs soon. After tweaking it a bit I would like some other opinions on if's better or not.

-S

[Eric Bilodeau]

The color shifts are probably not a compression thing, most likely they are related to the "automated de-saturation process", not as a consequence but I think that this particular chip seems to be much less chroma accurate in low light conditions, particularly on the skin tones. Witch is not the case of the sony models of miniDV I agree. Still with decent lighting it does real good, even in green screen, I suspect blue to be equally good.

Looking on the footage on a HD monitor gives real credit to it and surprisingly, those color shifts are much less apparent. Alex is right though, tweeking the image will worsen that in post, a good reason to increase the light. This camera does very good in fair lighting conditions.

Still, there are conditions where the image is totally screwed up. This camera is, needless to say, less than perfect but it does green screen without problem on my part. The increase in definition really is a major issue here. Let's be optimistic and assume that the next generation of HDV will have these issues solved :)

As for the chroma noise Alex showed on his site, it is indeed a HD1-10 related kind of noise. It appears in areas that are not enough lighted and in the red-orange-brown-pink areas of the image mostly and in low contrast zones and/or situations. That is why I think it is related to the de-saturation process. The techs might have skipped this problem by providing a wise de-saturation protocol to avoid the weird color shifts. It is not likely to be a compression noise. I thought that the de-saturation was to keep the bitrate but it might be related to that instead.

Still the chroma noise created by compression is somewhat equivalent to DV. But this noise is not the same. The combination of both indeed destroys a good image so we have to be cautious.

[Steve Mullen]

Based upon the easy compression of green and the difficult compression of blue and red, plus the likely greater sensitivity to green -- I expect Eric is correct about green-screen working fine.

Also, the chroma noise projected to 6-feet or on a $4000 JVC HD monitor is not terribly high. I think Paul may be correct that decoders vary in their quality. (Paul did you get a replacement Monovision?)

Yes, it is higher than modern 3-chip DV camcorders, but it is not all that terrible.

I remember thinking it was a bit like the VX700 which did not have a chroma noise filter. The next gen DV camcorders had a chroma noise filters and the noise went away. But at a price.

DSP filters trade resolution for better S/N. I'm not sure if that's what we want.

[Alex Raskin]

New info on HD10's chroma noise.

If you shoot using cam's B&W effect, the footage is originally black and white. There's no visible artifacts at all in the ares where color footage does show chroma noise.

If you shoot in color, then you have color noise.

I expected cam's B&W effect footage to be superior to the color footage *de-saturated in post*.

After all, if the noise is already there, and you simply take away all color, you still should see some brightness fluctuations where chroma noise "stains" used to be, right?

Wrong! I was surprised to discover that software desaturation works *equally* well as the cam's own B&W effect.

There's absolutely *no* brightness spots in place of color noise spots after desaturation.

Which means that the brightness of the "noisy" spots was perfect, just the color shifted.

Anyone cares to analyze this?

My only comfort at this time is that yes, I can acquire color footage and then desaturate it in post at will - without any loss of quality or any extra luma noise.
By the way, 50% desaturation already takes care of the chroma noise spots - but of course, almost all the "normal" color is gone as well...

[Eric Bilodeau]

The reason why it works equally well is simple, the shifts in the chroma are color shifts, not intensity shifts and on normal conditions, a desaturation post process will give results as good as the BW filter on camera. A lot of colors produce the same grey level if they display the same lightness or almost identical.

But in low light high noise situations, it is much better to use the BW filter since the de-saturation (unless made in YUV or lab by discarding the two chroma channels) will produce visible blocks in the final desaturated images since the chroma shifts are combined with the low light chroma compression noise.

De-saturating the image a little indeed does the trick of lowering the noise but at some expense...

[Paul Mogg]

Steve, I should probably report that the Monovision has been a nightmare for me. Though the picture is great when it works, it has been totally unreliable in my case. I am now awaiting a refund on mine, as I'm on my 3rd failed replacement set and have had several repair visits to no avail, I may have just been unlucky, but that's the sorry situation. If it was reliable I would probaly keep it, Monivision service has been very good about repairs and replacements though. It also has issues with the black levels, which are not at all consistant in dark scenes, and also with the VisionBox converter, which produces green vertical lines on screen. Not a good situation. If you know of any other native 720p capabel monitor I'd really like to know. I'm also interested in that $999 HD projector from B&H you mentioned, can you tell us the model?

Thanks