10 bit vs 8 bit output

[Paul Curtis]

Not sure whether to post this in the FS100 or F3 forum. But thought i'd try here first.

Has anyone got a sample of 10bit output vs 8bit from the F3, this seems like the larger failing of the FS100 but on a practical level i do wonder how much difference.

I remember when the EX1 coming out people doing lots of tests to determine whether the output was 10bit and really finding it difficult to tell (yes it was)

So any shots of a nice graduated sky for example?

many thanks
paul

[Alister Chapman]

If your looking at the raw camera output then you will find it just about impossible to see a difference with normal monitoring equipment. This is because internally the cameras process the images using more than 8 bits (probably at least 10 on the FS100, the EX3 is 12 bit) and then convert to 8 or 10 bit for output so you should have nice smooth mapping of graduations to the full 8 bit output. Then consider that most LCD monitors are not able to display even 8 bits. The vast majority of monitors have a 6 bit panel and even a rare 8 bit monitor wont display all 8 bits as it has to do a gamma correction at 8 bits and this results in less than 8 bits being displayed. 10 bit monitors are very rare and again as gamma correction is normally required there is rarely a 1:1 bit for bit mapping of the 10 bit signal, so even these don't show the full 10 bits of the input signal. So it becomes apparent that when you view the original material the differences will not normally not visible and often the only way to determine what the output signal actually is is with a data analyser that can decode the HDSDi stream and tell you whether the 2 extra bits actually contain useful image data or are just padding.

Where the 8 bit, 10 bit difference will become apparent is after grading and post production. I wrote a more in depth article here: Why rendering form 8 bit to 8 bit can be a bad thing to do. | XDCAM-USER.COM but basically when you start manipulating an 8 bit image you will see banding issues a lot sooner than with 10 bit due to the reduced number of luma/color shades in 8 bit. Stretch out or compress 8 bit and some of those shades get removed or shifted and when the number of steps/shades is borderline to start with if you start throwing more away you will get issues.

[David Heath]

Originally Posted by Paul Curtis

on a practical level i do wonder how much difference............

So any shots of a nice graduated sky for example?

Bit depth is not the only way to get banding, and it's far more complex than is generally realised.

Banding can also be caused by compression, and I've said before how you can easily demonstrate that. Use Photoshop, and form a black to white horizontal gradient. It will be 8 bit - but shouldn't show any banding. Now save the image as a JPEG in the most compressed form and see what happens. Hey presto - instant severe banding, even though it's still 8 bit. The vertical striping is caused solely by compression.

Noise can also have a big effect on banding, and here a bit of noise can be an advantage, it "dithers" the pixel values, so if post is done the effect of noise can be to mask the problems Alister refers to. This is why 10 bit only really becomes important for acquisition in very low noise cameras - and that tends to be only the most expensive.

The tendency is to think that even if little difference, 10 bit can only be better, can't it? Even if only by a little bit? Again, there is a little bit more to the answer. For the same compression quality, you must have a 25% higher bitrate for 10 bit than 8bit, with all else equal. It therefore may be that for a given bitrate, you will get less banding at 8 bit and lower overall compression than at 10 bit and higher compression factors.

[Paul Curtis]

A couple of great answers. I understand both and really i'm thinking or pondering whether the 10 bit of the F3 is actually worth double the price. I would normally take everything into 32bit linear and work with footage there if i'm doing any serious CC. Add a touch of noise and it can work wonders. I'd never work in an 8bit codec, first step is transcode to cineform or something similar.

It might be that it's better to get near uncompressed 422 off an FS100 rather than record to SxS on an F3 for most practical applications.

444 seems pointless as it's a bayer imager anyway, so the full resolution (compared to an EX1 for example) isn't really there.

FS100 with a recorder could be a better overall bet for me

cheers
paul

[Alister Chapman]

There are more differences between the FS100 and F3 than just the output bit depth. The F3 has higher dynamic range and better image processing that gives the images better verisimilitude (IMHO). in addition the F3 offers far greater image control through the picture profiles than the much narrower adjustment range offered in the FS100.

Because both cameras have such low noise levels the internal recordings end up being remarkably free of artefacts. If you are shooting progressive, the difference between 4:2:0 and 4:2:2 is small, it's not a night and day difference. Interlace is a different story with a much more significant difference.

[Paul Curtis]

Originally Posted by Alister Chapman

There are more differences between the FS100 and F3 than just the output bit depth. The F3 has higher dynamic range and better image processing that gives the images better verisimilitude (IMHO). in addition the F3 offers far greater image control through the picture profiles than the much narrower adjustment range offered in the FS100.

I realise that on paper but do we have any solid side by side samples that actually show this? From my memory of the few comparisons i've seen it's been nigh impossible to see any substantial difference (most because most side by sides are shown post compression). I'd love to see some full res side by side still demonstrating better range and processing. I don't know whether anyone has done this?

cheers
paul

[James Houk]

Originally Posted by Paul Curtis

I realise that on paper but do we have any solid side by side samples that actually show this? From my memory of the few comparisons i've seen it's been nigh impossible to see any substantial difference (most because most side by sides are shown post compression). I'd love to see some full res side by side still demonstrating better range and processing. I don't know whether anyone has done this?

cheers
paul

Well, you're right that compression can make accurate comparison more difficult, but if anyone is in a position to speak to the respective capabilities of the FS100 and PMW-F3, it's Alister Chapman.

My FS100 – F3 review. | XDCAM-USER.COM

Frame Grabs from FS100, F3 shoot. | XDCAM-USER.COM

Updated notes for FS100 – F3 Video Review. | XDCAM-USER.COM

If you'd prefer to hear it from Philip Bloom... Large chip camcorder comparison: AF100 vs F3 vs FS100. Includes FS100 review in Part 2 | Philip Bloom

[Paul Curtis]

Those frame grabs don't seem to work (or rather the link doesn't). Is that just me? I've seen the other comments but there's little empirical evidence that i could see for myself.

The frame grabs might be it though!

cheers
paul

[Alister Chapman]

Just checked and the link is working.

[Paul Curtis]

Originally Posted by Alister Chapman

Just checked and the link is working.

Alister,

Thanks but still no go for me. Click the link and i get a page can't be found

http://www.xdcam-user.com/?attachment_id=587

That's the link it's trying to get to. I don't know whether anyone else can confirm this or whether it's something local to me?

cheers
Paul

[Brian Drysdale]

I checked the link, it came up:

"Not Found

Apologies, but the page you requested could not be found. Perhaps searching will help".

[Alister Chapman]

OK, my apologies, I've checked again and my admin privileges on my site meant I was getting the link while regular readers were not.

Here's a new direct link: http://www.xdcam-user.com/samples/fs...rame-grabs.zip

[Doug Jensen]

I suggest people listen to Alister when he says there are big differences between the F3 and the FS100. I have been saying the same thing since before NAB when I first got my hands on an FS100. Now that I actually own both cameras, the differences are even more apparaent to me than ever. If anything, Alister is being too soft on the differences.

Anyone who thinks that by buying an FS100 they are somehow getting an F3 at 1/3 the price is just fooling themselves.

And before anyone asks, no I don't have time to post example footage or frame grabs comparing the cameras. Either take my word for it or do your own testing if you don't believe me . . . But you have been warned. The F3 is a baby F35 or 9000PL. The FS100 is a DSLR killer. Two different cameras for different uses, different expectations, and different budgets.

[Paul Curtis]

Originally Posted by Doug Jensen

I suggest people listen to Alister when he says there are big differences between the F3 and the FS100. I have been saying the same thing since before NAB when I first got my hands on an FS100. Now that I actually own both cameras, the differences are even more apparaent to me than ever. If anything, Alister is being too soft on the differences.

Anyone who thinks that by buying an FS100 they are somehow getting an F3 at 1/3 the price is just fooling themselves.

Most people aren't in the position to actually compare both of them. Whilst in terms of fitting into a traditional shooting workflow the F3 reigns king. When it comes down to actual image quality i've seen nothing yet that really shows major differences. I am not comparing Slog or anything like that, just a base F3 vs FS100 in terms of sensor and the image quality you can get out of it. I think Alister himself states they are very close in his review.

Thank you for taking the time to post but could you perhaps take a little more time and give some concrete examples of where you feel the differences are?

EDIT: I've downloaded those sample frames which are great. However none of the exposures between the cameras seem to match (which Alister explains is due to the LCDs of the two cameras not matching). Two of them have the FS100 clipping (with more shadow detail) whilst the house one is closer, the F3 a little over there. I haven't been able to find out what lenses were being used and whether they matched. The F3 lens seems to resolve higher - is that the lens or the camera at play here? The colours on the F3 seem a little too vivid, so again i'm not sure whether there was an attempt to matching settings or not? Also the detail setting seems higher on the F3 (the edge sharpness effect) and the compression is better on the F3 (which might be preserving more detail. It's certainly doing that in the shadows)

But if you monitor externally and record externally - i've still seen nothing that really makes a case for a quality difference between them to such a degree. Purely from image quality - not handling or workflow.

many thanks
paul

[Doug Jensen]

QUOTE: "I am not comparing Slog or anything like that, just a base F3 vs FS100 in terms of sensor and the image quality you can get out of it."

I'm not comparing S-LOG or anyting like that either, just the naked cameras. Not only is the picture better on the F3 (I challenge anyone to prove that statement is false) but so are the features and controls the F3 offers -- which are critical components of getting the job done consistently, quickly, efficiently, and reliably. The F3 is in a totally different league from the FS100.

The F3 excels in handling highlights because of the Hypergrammas and other sophisticated paint menu settings, dynamic range (even though some people say they are equal), the accuracy of zebra and peaking displays, file naming parameters, camera data files, sharing picture profile files, picture cache, timelapse, Assign Button options, overall build quality, speed and efficiency of the XDCAM workflow vs. NXCAM workflow, HDMI only vs. HDSDI + HDMI, and the list goes on and on.

However with all that said, can a person still get great images from an FS100? Absolutely. Will some people not mind giving up the features and controls of the F3? Absolutely. Will most FS100 buyers be perfectly happy with their camera choice? Absolutely. All I'm saying is that you should know what you are buying, and realize that you aren't getting BMW performance at a Chevy price. There lots of reasons why the F3 costs more, and in my opinion, is worth more. Different cameras for different folks.