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

[Piotr Wozniacki]

Hi Tom,

Thanks for the sound comments (as usually). This is of course a huge topic for discussion, and it contains immense number of variables - but let me just address a couple of your points (sorry for not being systematic about it - haven't got time right now). And, I did say this test isn't even pretending to be scientific :)

1. I can assure you that the increased noise is even more striking when in motion!

2. The recordings were 1080/25p (simultaneously to the nano and SxS)

3. Like you, I usually record at 100 Mbps. The 180 Mbps bitrate has been chosen here deliberately, in order to "test extremities", if you will. So was shooting the poorly lit object, rather than - say - a properly lit concert stage, or full sunshine landscape...

[Piotr Wozniacki]

Originally Posted by Gints Klimanis

Agreed. Piotr, aren't you able to grab frames as uncompressed PNG?

EDIT: Apologies, Piotr. I see that you posted uncompressed PNG of the red flowers in another thread.

Here you go (I can even do TIFF for you, but that would be just wasting the bandwidth :)):

[Tom Roper]

Originally Posted by Gints Klimanis

Agreed. Piotr, aren't you able to grab frames as uncompressed PNG?

EDIT: Apologies, Piotr. I see that you posted uncompressed PNG of the red flowers in another thread.

I thought the red flowers from the nanoflash were better in the other thread? Is there a problem just at the 140-180 mbps bitrates or does the 100 mbps show more noise as well?

I guess what's being said is that the Sony compression to 35 mbps HQ is superior to nanoflash 4:2:2?

It was always my opinion EX 35 mbps HQ was regarded unfairly, but what about those videos showing the showering of sparks from welding and grinding, and twisting motion and all that? It was clearly superior at 100 mbps? And the ocean surf, same thing? Now we are reporting nanoflash is noisy? A bit hard to understand. Maybe the 100 mbps bitrate is best overall? Or is the noise happening there too? I sure thought it looked clean.

[Tom Roper]

Originally Posted by Piotr Wozniacki

Here you go (I can even do TIFF for you, but that would be just wasting the bandwidth :)):

I still think it's wrong to upscale a crop to 1920x1080? What's the point? The image is being interpolated. The correct thing to do is view crops at 100%. (Appreciate the efforts)

[Piotr Wozniacki]

Originally Posted by Tom Roper

I still think it's wrong to upscale a crop to 1920x1080? What's the point? The image is being interpolated. The correct thing to do is view crops at 100%. (Appreciate the efforts)

Tom, the only reason I upscaled crops to fullHD size is that - like you - most people cannot see what I'm talking about in the regular, full screen grabs because they watch them on small monitor screens.

If you have access to a 50-incher, just please A-B the two original full screen pictures in the first post of this topic, and you will see the same difference.

[Tom Roper]

Understood.

Thanks Piotr.

[Gints Klimanis]

Originally Posted by Tom Roper

I thought the red flowers from the nanoflash were better in the other thread? Is there a problem just at the 140-180 mbps bitrates or does the 100 mbps show more noise as well?

I guess what's being said is that the Sony compression to 35 mbps HQ is superior to nanoflash 4:2:2?

The Nanoflash does a better job of preserving detail. Piotr's example using the cabin is a bit unfair because the color of the wood siding is nearly uniform and the increase in detail on the wood siding is perceived to be less valuable than the accuracy increase in capturing the noise. That is, some prefer a smoothed wood surface to a textured, noisy one.

I posted an example of elephant seals on the beach on this forum. The Nanoflash clearly renders the breaking ocean waves with less macro-blocking at 100 MBps. I did another test this weekend on a water faucet+closed hose that to create fine streams leaking from the seal, and the fine water streams showed much more detail on the Nanoflash.

CD should be posting more examples to demonstrate the Nanoflash advantage.

[Bob Grant]

Using images seems a bit flawed to me as evaluation is somewhat subjective.
I'd suggest closing the iris / lens hood and recording black. Then compare the results using a waveform monitor.

In my previous comment it was the waveform monitor in the Panasonic BT-LH1760 that I was looking at with a seriously under exposed image. If I can find the time and the gear is available I'll try to do a more scientific test and take snapshots off the Panny's LCD.
In general though I have to agree with previous comments, the difference in chroma sampling and the way an mpeg-2 encoder works at different bitrates more than likely explain what is happening. That's why I suggested doing an apple to apple comparison, run the CF at the same bitrate as the camera and see what the outcome is.

[Piotr Wozniacki]

Originally Posted by 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

Rafael,

Even though I believe that for showing a difference, just about any format is OK - I have repeated the two enlarged grabs in PNG (see post#32).

[Peter Moretti]

Look guys, it's clearly not an issue with rescaling a blow up or jpg compression. Piotr is seeing the issue and posting examples on the web to illustrate what he's seeing on his own computer w/ the raw footage. The posted images fairly represent what he's seeing, otherwise he wouldn't be wasting his time and everyone else's with this thread.

Okay, how to figure out what's going on.

1) Test the nano at different bit rates and long GOP vs I frame.

2) Test the nano in different lighting conditions.

3) See if where you bought the nano from would give you another unit to test.

4) Set up a static scene at home and record it to EX. Then send the component feed to a monitor. Compare the footage. While it's not looking at HD-SDI, I'm assuming you don't have an HD-SDI monitor, and the EX-1 does not have HDMI. If you see similar noise on the compenent feed, then you know it's the camera.

Just some ideas.

That all said, it would be GREAT for CD to reply here.

[Piotr Wozniacki]

Peter,

Thanks for encouragement. You are so right in saying:

"The posted images fairly represent what he's seeing, otherwise he wouldn't be wasting his time and everyone else's with this thread"...

As to your suggestions, I don't think comparing Component with HD-SDI /HDMI makes sense; the high frequency detail tend to be filtered out in Component connection (also depending on the cable quality), so in my experience, Component is always less noisy/detailed than SDI/HDMI. Apart from my 24" computer monitor, I have a 50" plasma hooked up to my editing PC, but that doesn't have SDI input. So, what I'm going to do in order to make sure where exactly the noise is increased in the chain, is to connect my nanoFlash HDMI output directly to the 50" plasma (now it drives my Marshall monitor), and - having set up a low-light scene likely to have considerable noise - try to compare:

- the HDMI output from the nanoFlash when not recording (live; the nano will serve as HD-SDI -> HDMI converter)
- the nanoFlash recorded picture (at various bitrates)
- the SxS recorded picture, with the EX1 in playback mode and the nano acting as the HD-SDI -> HDMI converter again).

Will report my findings.

But nobody from CD reacting for 4 days now (nor replaying to my email from 2 days ago) is something I just cannot understand, and am disappointed with...

[Peter Moretti]

Piotr,

Thanks for going through all this effort and sharing it with us. In CD's defense, it was a holiday weekend that extended into Monday here in the US, so they very well may be playing catch-up and a lot of times people use that weekend to plan vacations around.

But I hope they respond. I would think they would.

[Piotr Wozniacki]

Thanks for the info about the holiday in the US, Peter - I had no idea about the extended weekend you're having.

In that case, I'm still hoping Dan will respond the way he always did, when only he's back...

[Dan Keaton]

Dear Piotr,

I am very sorry that I have not been able to respond to your post until now. I saw your post Monday evening, just before I left on a business trip. Due to my travels, I have been unable to respond to emails until now. After reading your original post, I immediately discussed it with one of our engineers and asked them to respond.

My take on this is simple.

Codecs, when compressing images remove some detail. Lower bit-rate codecs remove more detail. Some high bit-rate codecs may remove no detail or almost no detail.

If one creates an image that has noise in it, on purpose or not, then the nanoFlash, when using high-bit rate options, will preseve that noise (or a great deal of that noise).

If one has a high quality HD-SDI monitor, a professional monitor, then one can monitor the live HD-SDI signal out of a camera. Run a test, and carefully examine the image, while recording the image to the nanoFlash.

Then playback the image on the same monitor. Using our high bit-rate options, the image should appear the same or very close.


As a side note, I had the opportunity to test some consumer HDMI televisions and monitors recently. I was surprised to see quite a lot of noise in the images. I was not expecting to see noise. Frankly, I have been spoiled by the images from a very nice Sony LMD-2450wHD 24" monitor.

With the same images, the Sony monitor is noise free to my eye, but two consumer monitors (consumer grade, under $375 for one, and $250 for the other, were very noisy.

I was testing these monitors to see if they were good enough to use at trade shows to demonstrate the nanoFlash. They were not.

[Piotr Wozniacki]

Originally Posted by Dan Keaton

Codecs, when compressing images remove some detail. Lower bit-rate codecs remove more detail. Some high bit-rate codecs may remove no detail or almost no detail.

If one creates an image that has noise in it, on purpose or not, then the nanoFlash, when using high-bit rate options, will preseve that noise (or a great deal of that noise).

Thanks Dan. This more or less confirms one of my own possible explanations (expressed also by a couple of others in this thread), that EX1's own, 35 Mbps 4:2:0 codec removes more noise along with quite some detail, while the nanoFlash'es codec retains the more detail (and noise, if present in the source picture), the higher bit rate it works at.

In other words, the GiCo rule at work :)

Considering the above, I guess that even though CD's latest information confirmed the potential of substantial quality increase with bitrates over 100 Mbps, there is a good reason to stick at the 100 Mbps as the "sweet spot" - and not just for storage consideration alone.

Especially with cameras like the EX1, which - under some circumstances (low light, uniform color areas in the scene, certain gamma curves and detail settings) - tend to produce a rather noisy picture...

But this experiment also made me think about another wish for the future nanoFlash firmware releases, which I'd like to know your opinion about:

- is it viable that CD adds some (user selectable from the menu), mild noise reduction circuitry?

This would make it possible to use all the benefits of higher bitrates (less compression artefacts), while not augmenting the level of noise from the source camera. Of course, at the cost of some detail reduction - but sometimes it could be beneficial (provided the NR can be switched on and off by the conscious user).

What do you think?