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Archive 2012 · D800: 12-bit RAW vs. 14-bit RAW
  
 
ausemmao
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p.5 #1 · p.5 #1 · D800: 12-bit RAW vs. 14-bit RAW


mshi wrote:
Only for shadows? Not entirely true because after all it's an equal opportunity provider. Take a look at some samples showing differences in both both Highlights and Shadows. Visual folks do visual way.

Shadows agrees with what we said.

Visual folks? Your 'highlight' sample is a shadow sample . The noise should have given that away (as should the fact that the upper samples are uncannily similar to the right hand side of the lower samples), but you can check on the site you pulled that from too.

http://www.earthboundlight.com/phototips/nikon-d300-d3-14-bit-versus-12-bit.html



THAT is the highlight version, and the biggest difference between them is the colour balance, which looks to be a result of inconsistent lighting or weird raw conversion (it's a green-magenta shift).



Apr 12, 2012 at 04:31 PM
elkhornsun
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p.5 #2 · p.5 #2 · D800: 12-bit RAW vs. 14-bit RAW


Over the years I have become more selective in my use of RAW as well as the bit level used. For images that are going into a catalog or on the web there is no reason to shoot at 14-bit and often little reason to even use RAW capture.

Portraits are one place where 14-bit is not going to offer any real world advantages over 12-bit in the print that is created. Same would apply to most wildlife prints.

I have spent too many hours wading through hundreds of images to find the "best" one for a print or project and have learned to be more judicious while shooting to minimize the "clutter" this creates which is a time vampire in every sense.



Apr 12, 2012 at 07:58 PM
taob
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p.5 #3 · p.5 #3 · D800: 12-bit RAW vs. 14-bit RAW


crewshin wrote:
Haha, but that demonstrates absolutely nothing in regards to the topic at hand.


You need to understand the context of those sample images. I responded to mshin's post of a well-exposed and well-captured 16-bit image. He was asserting that the quality of his example can be attributed to the 16-bit capture (rather than to the lack of AA filter, a great lens, good lighting technique, etc., etc.) I then demonstrated that bit depth often matters less than what most people think, thanks to dithering and noise. I successively halved the number of levels at each step, so people can judge for themselves.

Tweak the photo after each reduction and then see how far those bit depths get you.

Again, you may have missed the other dozen or so posts I made in this thread alone about the results of major adjustments on 12-bit vs 14-bit as well as lossy vs lossless compression.

Prove "huge" with a photo? I don't need to. Look at the math. 12288 MORE levels of precision. 12bit has only 4096 colors total.

Did you and afm901 take the same math class? A 12-bit capture allows for 4096 discrete data values, not colours. A 14-bit capture allows for 16384 discrete values, not colours. Mathematically, the difference is obvious. But if that's the only thing you consider, you've failed. As I mentioned in a previous post, we do not live in a perfect, mathematical world. Our capture devices, our display devices, our own eyes and brains... these are all analog devices. Since you are so seemingly keen on the math side of things, you may want to read up on probability theory, statistical mechanics, and signal processing. You will then have a better understanding of how images are actually captured, and why 12-bit vs 14-bit vs 16-bit often makes no difference, and when it might.

If you are the type of photographer that does push things around in post... then you will gain HUGE benefits from using 14bit lossless... yes... even over 12bit lossless. That's a 12288 precision difference between 12 and 14bit.

Again, you'll have to demonstrate this. If you are confident in your assertions, it should be easy for you to show us some examples of these "huge benefits" you speak of. But since you've chickened out of this discussion, I'm thinking you have nothing else to offer us.


Edited on Apr 15, 2012 at 10:43 PM · View previous versions



Apr 15, 2012 at 02:44 PM
taob
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p.5 #4 · p.5 #4 · D800: 12-bit RAW vs. 14-bit RAW


afm901 wrote:
A 12-bit file has 4096 colors per channel or 12288 colors for a three channel RGB file
A 14-bit file has 16384 colors per channel or 49152 colors for a three channel RGB file


I'm hoping you now realize that you multiply the numbers together. You don't add them up. A three-channel (RGB) 12-bit file can theoretically represent 2^12 x 2^12 x 2^12 different colour values. That's not 4096 + 4096 + 4096, but rather 4096 x 4096 x 4096 = 68719476736, or almost 69 billion colours. A 14-bit file results in 4398046511104, or almost 4.4 trillion colours.

It is believed that the human vision system can distinguish about 10 million colours. A 12-bit file is able to represent over 6000 times as many colours as we can see. A 14-bit file, over 400,000 times as many! To put it another way, I could show you about 440,000 different colours from a 14-bit file, and you would swear they are exactly the same colour.

All those extra colours are needed for two reasons. If we only had exactly 10 million colours to work with, they might not be the same 10 million colours our eyes can see. Everybody sees colour differently. So we need something that can encompass all of human vision (or at least as much of it as possible). The second reason is what we are talking about in this thread: the ability to push and pull an image so that the result still has enough colour information to recreate those 10 million colours we can see.


Edited on Apr 15, 2012 at 10:44 PM · View previous versions



Apr 15, 2012 at 02:56 PM
 

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taob
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p.5 #5 · p.5 #5 · D800: 12-bit RAW vs. 14-bit RAW


Here's another real-world example. I hope it shows that while math and information theory do reveal the truth about data compression, the practical effects of that compression is perhaps not as obvious.

This is one of the entrances to the Law Society of Upper Canada here in Toronto. It was shot on a sunny day, Sigma 85mm f/1.4 @ f/4 and 1/500 s. I was at ISO 100, so there is no way to hide any differences behind the noise. Because I have both highlight and shadow detail to bring out, I shot once as a 14-bit lossless NEF, and again as a 12-bit lossy NEF. Here is the original capture:







Here is the adjusted image, ACR 7.0 with Highlights -100, Whites -25 and Shadows +100. The main door in shadow is brought up by about 2 stops:







100% crop of area 1:












Area 2:












Area 3:












I won't say which is 12-bit and which is 14-bit yet, so look and judge for yourselves first. Is there a visible difference? Yes. Would I be quite happy with the results from either? Yes! And the funny thing is, when I examined each one, it turned out the version I preferred was actually the 12-bit lossy file!



Apr 15, 2012 at 03:19 PM
penpro
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p.5 #6 · p.5 #6 · D800: 12-bit RAW vs. 14-bit RAW


For those of you that have shown real world testing here I thank you for your hard work and sharing.

This is definitely helpful information when choosing what to shoot.

I'm a graphics programmer so the real math to all this I fully understand, the practical application of it and how it will affect the out come us never as straight forward.



Apr 15, 2012 at 03:21 PM
taob
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p.5 #7 · p.5 #7 · D800: 12-bit RAW vs. 14-bit RAW


Another example from lunch the other day. We were in a pub where the only light came from the windows along one wall of the room. I was shooting from the shadow side, of an unsuspecting table about 15 feet away. Here's the original as seen by the camera:







I did not want the HDR effect this time. I wanted to blow out the windows, so I simply pushed things up 3 stops with the Exposure slider in ACR 7.0:







100% crop of area 1:












Area 2:












Do you see big differences between the two? The fine detail on the first fellow's shirt, skin and beard appear to be equally well-preserved. You can certainly see a difference in tonal gradation and black clipping levels on the second fellow's suit sleeve, though I don't find either one objectionable.



Apr 15, 2012 at 03:29 PM
taob
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p.5 #8 · p.5 #8 · D800: 12-bit RAW vs. 14-bit RAW


Now that I've put the D800 through several thousand shots not just on tests, but on actual paying jobs, here is my conclusion: a 12-bit lossy NEF will produce just as good of an image as a 14-bit lossless NEF for my style of shooting. I don't shoot landscapes (I do weddings and portraits full time), I rarely do any sort of HDR processing, and I tend not to go nuts with filters and adjustment layers. If I have to rescue detail more than 2 stops under or 1 stop over, I'm not doing my job correctly. A 30MB NEF will produce essentially the same image quality as a 45MB NEF, for the way I shoot and the images I deliver to clients.

This has been the same conclusion from similar testing done with my D3S and D700, and to a lesser degree the D300 (one of my backup cameras). Along the way, I've been impressed by how well the D700 performs in low light, how the D3S is even better, and how the D800 manages to squeeze 36 million pixels onto the sensor without really compromising other aspects of image quality.

Thus, from an efficiency standpoint, I should be shooting 12-bit lossy NEFs. There is no perceivable loss of image quality, but there is a significant savings in terms of storage and data transmission times.

OTOH, storage isn't a big issue for me either. I went from 4GB cards in the D700 to 16GB cards in the D800. That more than makes up for the file size difference. I can shoot 14-bit lossless NEFs on the D800 and fit around the same number of images per card as I did on the D700 with 12-bit lossy NEFs. That means I don't need to keep track of more cards, or change cards more frequently during the day.

I also upgraded from a USB 2.0 card reader with SanDisk Extreme III cards to a USB 3.0 card reader with Lexar 400X cards. The former gave me about 20 MB/s throughput. The latter now gives me 80 MB/s throughput. Again, that makes up for the larger D800 file sizes.

Hard drives are still very cheap when it comes to bulk storage. I don't need fast hard drives for backup purposes, so a 2 TB drive costs less than $150. I can store 40,000 14-bit lossless NEFs or 60,000 12-bit lossless NEFs. If I deliver an average of 750 shots per wedding, I can store between 50 and 80 weddings on a drive. That works out to $3/wedding for 14-bit lossless, and $1.88 for 12-bit lossy. So long-term storage costs don't add up to much either.

I also backup finished weddings to Blu-ray, which then go off-site into a bank vault. This is where it gets a bit more interesting. Assuming a 750-shot average, shooting at 14-bit lossless will result in a data size of 33 GB. That's too big to fit on a single-layer 25GB BD. I'd either have to buy much more expensive dual-layer 50GB BD, or spend the time and hassle babysitting the burning of two discs. With 12-bit lossy, 750 files add up to 22 GB. That conveniently fits on a single disc, which means I can fire 'n forget the backup process. The entire wedding stays together, I don't have to keep track of multiple discs, etc. So in my case, the difference in NEF compression just happens to cross over that one-disc threshold in my backup process.

But for everything else, it really would not matter what mode I choose. It will not have a dramatic impact either way. Now, the debate between lossy and lossless DNG is interesting for other reasons... but I'll save that for another thread.





Apr 15, 2012 at 04:03 PM
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