12-bit image files can store up to 68 billion different shades of color. 14-bit image files store up to 4 trillion shades. That’s an enormous difference, so shouldn’t we always choose 14-bit when shooting RAW? Here’s a landscape I snapped, then found out later I had shot it in 12-bit RAW. Better toss this one out, right?
Depending on which class you took at the University of Google, the human eye is only capable of distinguishing between 2.5 and 16.8 million different shades of colors. If this is the case then wouldn’t 12-bit be plenty? Even 8-bit JPEGs can render 16.8 million colors.
There are many upsides to shooting 12-bit instead of 14-bit. The files are smaller, hence your camera’s buffer doesn’t fill up as fast, allowing longer action sequences to be caught before buffering out. 12-bit files take up less space on your memory cards – great for if you are on vacation without the ability to download your images every night. You can save money because you don’t need to purchase as many gigs of storage. Likewise, 12-bit hogs less space on your drives at home and the same number of 12-bit files load faster than if they were 14-bit. Lastly some cameras, such as Nikon’s D7100 and D7200 achieve higher burst rates when shot in 12-bit than in 14-bit.
So if the human eye can’t discern the difference and 12-bit has so many advantages, why doesn’t everyone just shoot in 12-bit? For the same reason brides want a real diamond, not a cubic zirconia. Admiring an engagement ring from a normal viewing distance, few people can tell the difference, but give that ring to a lab technician with a refractometer and they can distinguish the two (Note to readers: I will cut off your shutter finger if you forward this to my fiancé).
When given the choice I’ve always shot 14-bit, because as an American I know bigger is better and besides it’s my constitutional right to fritter away as many redundant bytes as I please. I went to the internet (I sense trouble coming) to validate my feelings and found a lab test where someone shot a lens chart with a DX body at 4 stops underexposed then zoomed in to 200% and sure enough, you could see a difference. Then I checked another site where test shots showed no difference. This was getting confusing for my puny brain so I decided to field test 12-bit versus 14-bit to see if I could tell any difference. I started out with landscapes – if anyone is picky about file quality it’s us landscape geeks. Bear in mind that these tests are in the field, not the lab, and though I tried my best to keep all parameters the same, there may be some slight variations due to Nature and/or the tolerances the camera is built to. I shot with a D810.
Here’s a nice yucca shot in 14-bit and properly exposed.
And here’s the same yucca in 12-bit.
I can’t tell a difference.
Next I tried a shot that would test the camera’s dynamic range with sunlit clouds and a shadowed foreground. I exposed not to blow out the highlights, which then resulted in the shadows being pretty underexposed, requiring me to pull the shadow detail back up in post. Here’s the original 14-bit file with no post-processing. (I won’t bore you with the 12-bit original – it looks identical.)
And here’s the 14-bit with the shadows recovered.
And the 12-bit.
Here’s 14-bit cropped in on some shadow detail.
And the 12-bit.
Oh crop, there’s no difference I can tell. I showed this to a photographer with more critical eyes than mine and she couldn’t tell a difference either. Maybe the difference is only visible in a final print. So I printed the two versions and still couldn’t tell a difference.
So far my tests were with well-exposed shots. It holds to reason that if I were to be able to tell a difference it would be in the dark values as when you’re courting the left side of the histogram, you’re dealing with a lot less raw information. After all, in dark conditions such as underexposure, fewer photons are being counted at each pixel site than when it is bright. (See Spencer Cox’s article about the theoretical advantages of having more data to work with by exposing to the right side of the histogram.)
I was driving through Northern Arizona late one afternoon and there were some clouds so I had to detour to The Mittens. Sadly the clouds started shrinking to where I would have a mediocre sunset shot. Rather than pack up and leave, I thought “ah ha”, time to run some more 12-bit versus 14-bit tests. But this time I’ll bracket the exposures and see what happens.
Rather than go through 30 samples of original shots, tweaked in post shots, and tweaked and cropped to 100% shots, lets fast-forward to the most underexposed sample. First the unprocessed 14-bit.
And 12-bit unprocessed.
14-bit tweaked and cropped to 100%.
12-bit tweaked and cropped to 100%.
What’s a guy got to do to see a difference? These are virtually identical, especially given that this was natural light, which isn’t always even and there could be slight exposure variations due to tiny shutter speed and aperture differences. If I can tell any difference at all it might be a teensy bit more contrast in the tweaked 12-bit samples.
The above tweaking was from letting Lightroom auto-tone the images. Not really the best presentation of this file so I went in and tweaked more to my liking and applied the exact same parameters to each file.
14-bit tweaked.
And 12-bit tweaked.
Squinting real hard I’m learning two things. First, I can’t tell the difference between these 12- and 14-bit images unless I look at the metadata. Second, my 24-120 Nikkor is pretty soft in the corners – I should have shot my 50mm.
You may have noticed all of these so far are at base ISO. Maybe I need to go to higher ISOs where the camera will have to amplify the signal hence we might encounter some noticeable differences. I went inside to get low enough light.
Again, instead of running you through dozens of tedious samples, we’ll cut to the chase. These are at ISO 3200. The scene has a ridiculous dynamic range from sunlit bushes outside the window to deeply shadowed pillows inside. First the untweaked 14-bit.
Now the untweaked 12-bit.
The 12-bit looks a tad brighter. The following had identical tweaks save the exposure of the 14-bit was boosted a tad to match the 12-bit. Tweaked and cropped 14-bit.
Tweaked and cropped 12-bit.
Just maybe an eensy bit more constrast in the 12-bit, but I reckon if you printed these out and swapped them around and showed them to me I couldn’t pick out one from the other.
I guess we’ll have get ridiculous and head to that special place where histograms go to die.
Here’s the 14-bit.
And the original histogram. Oh my, even Michael Moore doesn’t expose that far left.
And 12-bits of despair.
Again the 12-bit looks a tiny bit lighter so this is perhaps a 12-bit/14-bit D810 thing, not any variation in light levels or shutter speed/aperture tolerances.
14-bits cropped and tweaked.
12-bits cropped and tweaked with the same parameters.
At last, a difference I can see – the 12-bit file after extreme processing is having some trouble holding highlight detail. However I can see a tiny bit more shadow detail in the 12-bit file. This might be due to the f/16 aperture not closing as far on that particular exposure, hence letting a few more photons reach the sensor. Or maybe not. Either way, both 12-bit and 14-bit files look like they drank too much and puked all over themselves.
Let’s try again. Here’s a scene in Petrified Forest. I’m underexposing heavily and stopped way down trying to get a small, tight sunstar and seeing just how much I can retrieve from the shadows in post. (This would be a much better candidate for exposure blending, but we’re running a test here.)
Here’s the untweaked files. First the 14-bit.
Now the 12-bit.
And now with identical post processing. -100 highlights, +100 shadows, +2.45 exposure, and various other tweaks.
The 14-bit.
And the 12-bit.
At last, I created a practical field test that is showing a difference. The 12-bit version has got an unpleasant greenish cast and the 14-bit is trending slightly magenta. Also it looks like there is more shadow detail in the 12-bit. Let’s fix the color in the 12-bit shot as seen below.
Voila. Looks great now and I like the extra shadow detail recovery. As I’ve already gone to +100 in the shadows there’s no further global adjustments I can give the 14-bit without blowing out my sunstar. I’d have to do local dodging and burning to match the two.
The takeaway I got from all this is that worrying about having 14-bit files instead of 12-bit is silly if you expose well or even just don’t mess up too bad. Good post-processing can give results that make it hard if not impossible to distinguish between 12- and 14-bit files. I did these tests to mimic situations I might encounter. I encourage readers to do their own tests with the sort of subjects they shoot. Feel free to share your results in the comments section.
All said and done, will I switch to shooting 12-bit? Psychologically this tears me apart knowing my files won’t be all they can be. Furthermore I like to photograph birds. They have four cone types in their eyes versus three for humans, hence have far superior color vision, up to ten times better. What if I want to sell family portraits to this Mallard mom?
Us humans can’t see the difference, but Mama Mallard sure will. Aw, those Mallards are pretty stingy anyway. I’ll just switch to 12-bit and increase my chance of getting the shot (through shameless spray and pray tactics) rather than getting a bigger file I can’t appreciate. And I can always switch back to 14-bit when conditions dictate I should – like the next time I’m shooting handheld candlelit test chart shots and forget to remove my 6-stop ND filter.
Text and photos ©John Sherman
I think Nikon describes it well on their website. It’s not about more resolution or details, it’s about higher precision for each individual pixel. And since cameras have gotten pretty good when it comes to representing colours accurately, that probably explains why it’s so hard to see a difference between 12 and 14 bit :)
These tests pretty much push the luminance channel properties. I am not sure either that I would see the difference between 12 and 14 bits but (there’s always a but), trying to photographs my wife’s paintings that pretty much cover the entire chromaticity and luminance space, that would be where I would go for a test of this. I finally have a X-RITE classic chart and even using that, if I underexpose, I cannot get dark shades right. A color calibrated workflow includes (albeit small but nevertheless) a matrix inversion which inherently magnifies errors (that’s just math). Perhaps not that much, I can’t say but that and the fact that our perception is more sensitive to color error than luminance… Read more »
I can see the difference between the 14 and 12 bit in every example –in some examples, the difference is very small. However, look at the final example, the photos just before the mallard. Notice the mounds under the 4 small spots of sun glare. Huge difference.
Give this guy the pepsi challenge.
I love what u did…love the humour pls help me I saw a guy who had a raw file and he made multiple exposures and then merged the photo into one hdr photo can I do this my raw video file ..like automatic or even a procesess
This article is so misleading. To be clear… you show exported sRGB photos which are 8-bit and can show about 16 millions tonal variations. Human eye can differentiate about million. So what you claim depends on how you exported them. However… you want 14-bit RAW instead 12-bit when editing photos to prevent color bending. It is clear you made a mistake when exporting the photo to sRGB (to show here) where you see greenish cast. Properly exporting the photo would show no difference. This article should not exist. You do not present 14-bit photo anywhere, because there are no such means in this world, event when printing professionally. Browsers and printing services rely on 8-bit sRGB. And yes, 10-bit screens… Read more »
You’re a funny guy. Funny, you know, like a clown. A Camera Clown.
What a good share! Kudos and keep on shoting, cheers!
MOST or Many monitors are 8 bit. Windows 7 on up supports 10 bit as do the new iMacs. Now? Can you SEE the diff between 12 and 14 bit color on a 10 bit montor, even supposing a proper calibration? I don’t think so, but don’t really know. I suspect but can’t prove that 14 bit color depth is a sort of ‘future proof’ step we can easily take today. As kind of an aside? Go to youtube and listen to high-end loudspeakers. They ALL sound pretty much the same coming out the nasty little speakers which are the stock-in-trade of the modern computer. Even when I plug in my good Grados, I can’t tell. But thru my stereo?… Read more »
Where I notice differences with RAW at different bit depth is with skin tones which have yellow as part of their color and reducing the bit buckets for this segment of the spectrum is something I notice with no difficult. If my scenes were predominately brown then color fidelity would be of little or any importance. Good that you used low ISO settings at least, as with high ISO the DR is already truncated and 14-bit capture is a waste of bits.
John, the biggest advantage 14 Bit over 12 bits, that you can raise the sharpness of the image in postprocessing by 150% and the picture will not break into pixels, when I found it, was in shock. Also, the overall impression of the image looks more sophisticated!
“The overall impression of the image looks more sophisticated”
WOW! Do you have examples to illustrate the added sophistication?
Interesting, ill have to test this to see if it is true or not and if so to what degree does the sharpness really extend. My understanding of how sharpening and bit-depth works I wouldn’t expect results like that, but I could be wrong and improved sharpness would definitely be a benefit to me, especially for some of my softer lenses, so I hope you are right.