Noise comparison: 35/4:2:0 vs. 180/4:2:2

[Piotr Wozniacki]

Here is another - far from scientific - comparison; this time I wanted to compare the noise in the EX1 picture (35 Mbps, 4:2:0, to the left) with that generated by the nanoFlash at 180 Mbps Long-GoP, 4:2:2 (right side picture).

Please take a look at the two screen grabs below; the left one is from the EX1. Please, compare them at a full HD screen of at least 50", or enlarge on your computer monitor (e.g. so that you can just see the wooden barn area directly around the square window).

As can be seen, the nanoFlash image is much, much more noisy!

Now, I have deliberately chosen a back-lit scene like this, and a picture profile not designed to minimize the chroma noise, so that the results are more readily visible. But frankly, I never suspected the difference would be so great, and not in favour of the nanoFlash...

Somebody more knowledgeable, please explain:

1. Is my nanoFlash faulty (I don't think so)?
2. Is the EX1 using some noise-reduction, which can not be turned off and is active in all PP settings - regardless of detail, matrix or gamma settings?
3. Or, is the noise visible in the nanoFlash recording a side-effect of the deeper color resolution the nano is using?

PS After a second thought, I guess the answer to my dilemma is simple:

The more noise "resolution" (read: visibility) is just a price for the more color resolution of the nanoFlash. It almost looks like the macroblocking at 35 Mbps is "masking" the grain, visible as excessive noise in the 180 Mbps, nanoFlash picture...

Any other ideas?

[Rafael Amador]

Piotr,
The pictures are JPEG.
Not valid for a test.
Use PNG, Targa or TIFF to make any comparation.

I've made many-many tests comparing the Nano vs the SxS files, and no way the SxS beats the Nano.
Rafael

[Piotr Wozniacki]

Anybody?

I must say I'm shocked with the above results. The EX1 camera - IMHO - has only one flaw (relatively speaking), and that's the noise when lighting is low. When buying the nanoFlash, I was secretly hoping this would be improved, as well. Since the very first use of my nano I already knew it is not (it cannot be) - but why is it made so much worse?!!

Dan, Mike and Tommy - could you comment, please? Is my observation consistent with your results of the many nanoFlash testing you preformed? If so, is my "theory" above true? I mean, this would best be described by the saying "Sh#t in, [even more] sh#t out"...

If not, could anything be wrong with my camera SDI output, the SDI cable, or... the nanoFlash?

Please comment!

[Adam Stanislav]

I trust you meant the saying "Garbage in, garbage out," usually just shortened to GIGO.

[Piotr Wozniacki]

Adam,

In the CAD/CAM/CAE industry, we use the SISO version :)

[Piotr Wozniacki]

Dear Dan,

I realize this comparison might be somewhat embarrassing to CD (unless a pretty obvious explanation exists) - but please address it, nevertheless.

In case one cannot see the striking difference in grain when watching the whole 1920x1080 frames, I placed below small fragments of the grabs from the original post (EX1 - left, nano - right hand side).

[Adam Stanislav]

I can see the difference now that you made the closeup. I am not CD, so this is just my opinion, but it seems to me the difference is between 4:2:0 and 4:2:2 and between the low and high bit rate. That is, as you said yourself, the EX3 does not perform that well under low light conditions, so all that noise comes from the EX3 to the nF and the nF gives you what it gets as it gets it.

But the EX3 does not show it all to you because it throws some detail away in 4:2:0 and a lower bit rate, which just happens to smooth out this particular image.

It is also possible that Sony knows about the low light problem (I mean, they have to know), so they may be compensating for it, cleaning it up in the firmware, but they still send out the uncompensated data to the nF, which, as a general device, has no way of knowing about the problem, so it just gives you what it has received.

So, yes, it's GIGO. But the EX3 may be giving you specific GICO (garbage in, compost out) because they compensate for the garbage.

[Piotr Wozniacki]

Thanks Adam - you more or less confirmed all my "theories" and possible explanations. Including the one about some permanent noise reduction going on in the EX cameras, independent of PP settings and NOT applied to the SDI output - only used directly prior to the camera's own compression by its internal, 35 Mbps encoder (see http://www.dvinfo.net/forum/sony-xdc...ctive-ex1.html)...

BTW, a similar feature was overdone in the otherwise great little HDV camera from Sony - the V1 - where instead of noise/grain, excessive macroblocking and "oil pain effect" was visible, even without magnification.

Well, I guess every EX1/3 - nanoFlash combo user must simply keep in mind the "augmenting GiGo", or GiCo, rule :)

[Garrett Low]

Piotr,

What were the settings on your EX1? Gain, PP detail, gamma?

Garrett

[Piotr Wozniacki]

Garrett,

I didn't write about PP settings because I just wanted to point out that the nanofile can be actually more noisy at 180 Mbps and with 4:2:2 color, than the EX1 file encoded at 35 Mbps, 4:2:0.

But since you asked, here are the main settings:

- gain: -3 dB
- matrix: HiSat
- detail: on, at 0 (frequency, white and black limits at some 50'ties)
- gamma: Cine3

[Piotr Wozniacki]

Actually, when I think more about it - and assuming there IS some noise-reduction circuitry on the EX1/3 which doesn't influence the SDI stream - it's quite possible that some PP settings exist that would optimize the signal for the nanoFlash to compress at its high datarates and color resolution, and that those settings might differ from those, optimized for the EX cameras' own encoder.

But with so many variables, starting another "PP settings for the nanoFlash" thread on the EX1 forum is beyond my imagination. Certainly not possible without a little help from out CD Friends (or at least recognizing the problem by them)...

[Peter Moretti]

If you look at the detial in the tree bark and the roof you'll see that the nanoFlash did a better job. I think you are right in your assumption that the nano records everything w/ more detail, including noise.

I'd rather have the extra detail; noise you can always try to get rid of in post.

P.S. Can you post uncompressed grabs? The jpg compression kind of throws another variable into the equation.

[Garrett Low]

I would tend to believe in the theory that the NF is just recording more information. The noise that is being produced by the sensor is just not retained in the 35Mbps 4:2:0 capture. It is lost due to the compression. I do know that some of the Gamma settings produce more noise than others. I wonder if you'd get the same results if you set your EX1 back to factory default settings?

Garrett

[Rafael Amador]

Piotr,
You can not compare pictures using JPEG.
You must use PNG, Targa, TIFF or so.
rafael

[David Cherniack]

Piotr,

On the EX1 there's a switch in Picture Profiles that does noise reduction. Are you sure that switch is not turned on? That would account for the relative lack of noise in the EX image.

David