Bit depth = levels of gradient?

Started 3 months ago | Discussions
J A C S
J A C S Forum Pro • Posts: 14,769
Re: Bit depth = levels of gradient?
1

filmrescue wrote:

Another poster suggested that the reason I sometimes get banding is because of noise and not because of bit depth when capturing very low contrast B&W negatives with a DSLR. I'm not fully understanding that though. The banding goes away when I scan it with an actual film scanner at 16 bit but maybe he's right and that's not a bit depth issue.

Why don't you post some scans. Who knows what your scanner is doing under the hood. It might not use your bits efficiently or it might convert to low quality JPEGs, etc.

My own scans show enough grain to think that posterization should not be a problem but on some of them, I do see posterization. Most likely a poor conversion (Nikon Coolscan 4000ED if I remember well, 14 bit).

BTW, the tonal range calculations are valid at a reference resolution for the highest frequencies only, roughly speaking. In large low frequency areas, like sky, etc., the extra bits might help.

OP filmrescue Contributing Member • Posts: 805
Re: Bit depth = levels of gradient?

J A C S wrote:

filmrescue wrote:

Another poster suggested that the reason I sometimes get banding is because of noise and not because of bit depth when capturing very low contrast B&W negatives with a DSLR. I'm not fully understanding that though. The banding goes away when I scan it with an actual film scanner at 16 bit but maybe he's right and that's not a bit depth issue.

Why don't you post some scans. Who knows what your scanner is doing under the hood. It might not use your bits efficiently or it might convert to low quality JPEGs, etc.

My own scans show enough grain to think that posterization should not be a problem but on some of them, I do see posterization. Most likely a poor conversion (Nikon Coolscan 4000ED if I remember well, 14 bit).

BTW, the tonal range calculations are valid at a reference resolution for the highest frequencies only, roughly speaking. In large low frequency areas, like sky, etc., the extra bits might help.

Thanks Jacs...I'll try to do that tomorrow when that computer is back on the network here.  I think I'm maybe worrying about it too much though because as another poster brought my attention to that with the extremely low contrast negatives that we're capturing, noise is overwhelming everything anyway when we try to bring things up to normal values and banding is only a small issue in comparison and relatively rare. It might be coming from something different than I thought it was.

We're just in the market for a new capture camera now so I was hoping to strike off the list one of the issues we sometimes see because we finally have a budget for something decent...up to 25,000 USD or so but if I can do it for a much smaller dollar amount I'll want to do that. The big dollars come with the 16 bit camera systems.
BTW...this needs to be done with a camera and not a scanner for a number of different reasons. To low contrast to marquee the frame, sometimes too dense for a scanner to see through the film and sometimes we need to capture film while it's under water...long explanation for that.

knickerhawk Veteran Member • Posts: 6,355
I think you're getting misleading/unhelpful advice here
1

filmrescue wrote:

I've been searching around to find some sort of chart or list that tells me how many levels of gradient there is for different single channel bit depths but I'm not having a lot of luck. Can anyone fill me in or link me to the info I'm looking for. I'd like to see from 2 all the way up to 20 or so.

Your problem isn't about too much noise in the deep shadows limiting the dynamic range of the image. Indeed, more noise would actually reduce the appearance of posterization/banding that you're seeing. And since you're scanning negatives and presumably inverting them to positives, most of the image noise should be present in the highlights, not the shadows, of the output image. The dithering effect of the noise should actually mask posterization, not make it worse.  Noise is NOT the enemy here!

What's really happening is that the low contrast scans you're performing require significant tonal adjustments in your photo editor. Since you need to invert, pretty much any subsequent contrast adjustment is going to induce posterization in your (positive) highlights ESPECIALLY if there wasn't much noise to dither away the tonal transitional borders. If, in addition, those edits are done in 8-bit mode (even if the image has not been saved to JPEG),  you're absolutely guaranteed to get posterization in the lighter tones due to quantization errors introduced by the editor during the tonal adjustment. The better strategy here rather than going out and buying a new camera might be to scan/shoot the negatives twice - once exposing for the highlights and once exposing for the shadows - and then layering/merging in post.

Good luck.

Tom_N Forum Pro • Posts: 15,911
Re: Bit depth = levels of gradient?

filmrescue wrote:

John Sheehy wrote:

J A C S wrote:

The levels are as many as I said. How many of them are distinguishable in a typical photo with whatever criterion, is a different question.

The OP isn't factoring in noise, though, so the OP is basically applying math to myth.

Explain please.

((2 ^ Bit_Depth) ^ Number_Of_Channels) is one limiting factor.

You can't do any better than that, but depending on other factors like the range of tonal values in the photo, or the calibration of your scanner or display system, or the limits of human perception, you could do worse. Is 0 the complete absence of light? Is (2^Bit_Depth - 1) the brightest light you could ever handle? Are the levels between evenly spaced?

Another way to see this is to consider 80-bit-per-channel representation. 2^80 is said to be roughly the number of elementary particles (protons, neutrons, neutrinos, electrons, and photons) in the observable universe. While your gear might be able to store 80-bit-per-channel numbers, there's no way that DACs, ADCs, displays, scanners, and printers could handle 2^80 gradations accurately. Nor could your eyes see all of them.

ERROR: Not able to count anywhere near 2^240 photons at this photo-site. There are not that many photons in the entire Universe. Would you like to move to an imaginary Universe?

bclaff Veteran Member • Posts: 8,699
Re: Bit depth = levels of gradient?
2

John Sheehy wrote:

...

I just checked the RAW values from a 12x10-pixel tile from a single RAW color channel of an ISO 100 14-bit RAW, from a very out-of-focus blank wall, and the average RAW value was about 11,500 with values ranging from about 9,500 to 14,500. No value was used twice. 120 different values, over a range of 5000 values. This was a bright tone, only a fraction of a stop below the highlight clipping point. Your model would be expecting just a few, very close tones, most likely, but it's nothing like that. The reality of RAW capture is jagged and noisy. Smooth gradients only appear through dithering.

Kudos for trying to supply a concrete example; but something is wrong, I suspect you combined channels that had very different signal levels.

FWIW, from the center of a D500 flat frame (about 1000 pixels):

The top two lines are the measurements; the rest are calculated.
Because this approach ignores things like PRNU the numbers are approximate but make sense. (Remember on the Nikon R and B are slightly scaled for "white balance pre-conditioning")
The bottom three row are adjusted so BlackLevel is zero.

Still, it's pretty clear to see that even at a relatively low signal level of around 3000DN which is about 18% with noise of about 30DN and using +-2 standard deviations values between 2940DN to 3060DN would be statistically indistinguishable.

12400DN is about 1/3 stop from WhiteLevel and there noise rises to 60DN; 12280DN-12520DN would be the +- 2 standard deviation range.

Also, FWIW, this is all at the pixel level and at normal "print" and viewing distances tones are even harder to tell apart.

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J A C S
J A C S Forum Pro • Posts: 14,769
Re: Bit depth = levels of gradient?
1

To challenge the common wisdom, here is a (sharp) gradient which jumps by 5 or so units in sRGB with added noise with st. dev. about 22.5. I did not convert to a linear space but for such relatively small numbers, there is no much need for it. The jump of the gradient is about 1/4 of the noise level, and it is still visible.

I also tried smoother figures and I can see them behind the noise.

D Cox Forum Pro • Posts: 23,886
Re: Bit depth = levels of gradient?

filmrescue wrote:

bclaff wrote:

filmrescue wrote:

I've been searching around to find some sort of chart or list that tells me how many levels of gradient there is for different single channel bit depths but I'm not having a lot of luck. Can anyone fill me in or link me to the info I'm looking for. I'd like to see from 2 all the way up to 20 or so.

The answer is not simple and is not the answer you will typically receive.
For example, with most systems there is no visible difference between 14-bits and 12-bits; and certain ly a factor of 4 difference.

You may want to look at what DxOMark call "Tonal Range".

What exactly are you trying to accomplish.

Primarily to be able to talk intelligently about why to be using a high bit depth capture system when capturing extremely low contrast negatives.
Also to be able to calculate for instance, if the negative I'm capturing is occupying 5 percent of the tonal range from absolute black to absolute white, how many levels of gradient do I have to work with if I use a 16 bit scanner or high end camera vs a 12 bit or 14 bit camera and at what point can I expect to see posterization given the capture system.

The other numbers for other bit depths are primarily just because I was curious.

If you are talking about digitizing B&W negatives (silver based), my experience is that the crucial thing is to resolve the grain sharply. Low contrast negatives are not a problem.  It's easy enough to adjust the white and black points in the image to give a full range of tones from what was a narrow band of pale greys.

The problem with low contrast negatives is that the signal-to-noise ratio is poor, so every speck of dust shows clearly. This is equally a problem in the darkroom, using traditional printing methods.

Any high resolution camera such as a Sony A7rii or a Sigma sdQH, with a good macro lens at its best aperture, will do the job.

High contrast originals such as most colour slides are a bigger problem. Some cameras have a built in HDR feature which is helpful. The new Panasonic full-frame cameras seem to have a very good dynamic range, but the high resolution model is extremely expensive.

Here's a very thin neg -- it was taken on some kind of ultra-fine-grain film -- and a positive result.

D Cox Forum Pro • Posts: 23,886
Re: Bit depth = levels of gradient?

filmrescue wrote:

John Sheehy wrote:

J A C S wrote:

The levels are as many as I said. How many of them are distinguishable in a typical photo with whatever criterion, is a different question.

The OP isn't factoring in noise, though, so the OP is basically applying math to myth.

Explain please. This ultimately is to calculate how many levels of gradient I would have to work with given different systems of capturing extremely low contrast film negatives. In practical use, it isn't noise that I see when capturing a low contrast film negative with 12 BIT dslr vs a 16 bit scanner it's posterization because I don't have enough levels of gradient with a 12 bit capture for an extremely low contrast negative. Not sure how that's myth.

What's the resolution of your camera, what area of film are you capturing, and are you using a good macro lens ?

D Cox Forum Pro • Posts: 23,886
Re: Bit depth = levels of gradient?

filmrescue wrote:

John Sheehy wrote:

filmrescue wrote:

Thanks for your thoughtful answer. I do have negatives that are captured with a DSLR that maybe occupy 5% of the tonal range where I end up with what I thought would be best described as posterization or banding that will disappear after I scanned them with a 16 bit actual film scanner.

What file format? JPEG tends to create posterization to make more compressible images. RAW captures are rarely posterized except in near-blacks in a small number of cameras, mostly the first Exmor sensors that had too little noise at base ISO for 12 bits.

I need to go back and look at what's going on in ACR but I generally only see the jpegs after the work is done (by someone else who works here) The original files are 12 bit NEFs and are opened as 16 bit files and saved as jpegs. The banding is fairly uncommon and only manifests itself if the conditions are right. Conditions being right meaning that the image isn't overwhelmed by actual distressed film issues so that what appears to be a digital artifact comes through in the form of banding. Perhaps the issue I'm concerned about is only showing up in the save to JPEG.

hat's quite likely. Try PNG files instead.

So you're saying that's not coming from a lack of band width but from noise?

Not posterization. Posterization is a lack of noise before quantization.

Maybe I have my terminology wrong. I thought "posterization" and "banding" were interchangable?

They are, except that the word "banding" gets used for other faults too.

What he is saying is that dither (perhaps from shot noise) greatly reduces the visibility of banding.

Bear in mind that B&W prints use only one or two bits, with dither.

Yes, of course as you bring up contrast you bring up all sorts of other issues, grain, dust, scratches, mottling...all minor imperfections become major issues.

The less artifacts you get in the capture, the less you'll see when you boost the contrast. You could consider using the principals of astrophotography with multiple exposure to minimize any artifacts that aren't already in the film.

I had considered trying that at some point but there's only so much that can be done at the price point we charge...in the end though you're onto something about noise albeit in my case the biggest issue is analogue noise in the form of film grain overwhelming the image.

Grain looks worse if it isn't sharply resolved. This is Grain Aliasing. I suggest reading this:

http://www.normankoren.com/Tutorials/MTF8.html

The original point of this post was I'm trying to make a decision on a new capture camera for when we photograph these negatives with a camera. A camera because so many of them are extremely low contrast to the point, you can't find the frames with a preview scan on an actual film scanner and often the negatives are so dense, an actual film scanner can't scan through them. For context, my company specializes in the processing of lost and found expired film...that's why we deal with so many terrible negatives.
Any thoughts on what would be the actual best thing to do our captures with. in contention right now is ...
A Nikon D850 - the most affordable option

I think any camera with 35 Megapixels or more will do. I used a Sigma sdQH, which uses a Foveon sensor and gives a similar resolution although nominally only 25 Mpix.

The Nikon should do fine. It might be best used in Live View mode to avoid any vibration.

A Microbox Book2net book scanning camera - 16 bit and multispectral but not sure if the multispectral part of that will help us or not. We have test film with them now.

A Fuji GFX 100

A Phase One ixg with their DT film scanning set up - this is likely more of a pipe dream because it's hardly affordable for us but if it does something amazing we'd probably find a way.
Most of these were chosen because they're 16 bit...You don't think we need that? I'd love your thoughts on any of these as a film capture device. You seem well informed.

My opinion is that you don't need 16 bit.

WunWegWunDarWun Regular Member • Posts: 410
Re: Bit depth = levels of gradient?

filmrescue wrote:

J A C S wrote:

filmrescue wrote:

Another poster suggested that the reason I sometimes get banding is because of noise and not because of bit depth when capturing very low contrast B&W negatives with a DSLR. I'm not fully understanding that though. The banding goes away when I scan it with an actual film scanner at 16 bit but maybe he's right and that's not a bit depth issue.

Why don't you post some scans. Who knows what your scanner is doing under the hood. It might not use your bits efficiently or it might convert to low quality JPEGs, etc.

My own scans show enough grain to think that posterization should not be a problem but on some of them, I do see posterization. Most likely a poor conversion (Nikon Coolscan 4000ED if I remember well, 14 bit).

BTW, the tonal range calculations are valid at a reference resolution for the highest frequencies only, roughly speaking. In large low frequency areas, like sky, etc., the extra bits might help.

Thanks Jacs...I'll try to do that tomorrow when that computer is back on the network here. I think I'm maybe worrying about it too much though because as another poster brought my attention to that with the extremely low contrast negatives that we're capturing, noise is overwhelming everything anyway when we try to bring things up to normal values and banding is only a small issue in comparison and relatively rare. It might be coming from something different than I thought it was.

We're just in the market for a new capture camera now so I was hoping to strike off the list one of the issues we sometimes see because we finally have a budget for something decent...up to 25,000 USD or so but if I can do it for a much smaller dollar amount I'll want to do that. The big dollars come with the 16 bit camera systems.
BTW...this needs to be done with a camera and not a scanner for a number of different reasons. To low contrast to marquee the frame, sometimes too dense for a scanner to see through the film and sometimes we need to capture film while it's under water...long explanation for that.

If you are only going to be digitizing 135 film check out a Nkon ES-2 digitzing adapter set, combined with a d850 and a suitable macro lens - you will have over $20k left and no film information will be lost.

John Sheehy Forum Pro • Posts: 22,024
Re: Bit depth = levels of gradient?

bclaff wrote:

John Sheehy wrote:

...

I just checked the RAW values from a 12x10-pixel tile from a single RAW color channel of an ISO 100 14-bit RAW, from a very out-of-focus blank wall, and the average RAW value was about 11,500 with values ranging from about 9,500 to 14,500. No value was used twice. 120 different values, over a range of 5000 values. This was a bright tone, only a fraction of a stop below the highlight clipping point. Your model would be expecting just a few, very close tones, most likely, but it's nothing like that. The reality of RAW capture is jagged and noisy. Smooth gradients only appear through dithering.

Kudos for trying to supply a concrete example; but something is wrong, I suspect you combined channels that had very different signal levels.

I thought that the spread was a little wide when I looked at it, but it was from a single channel, and it looked "flat" or even at a small size. I just zoomed into it now, which I should have done last night, and it does actually have a little gradient, with one corner a little darker. I should have just taken a fresh shot designed for the purpose.

John Sheehy Forum Pro • Posts: 22,024
Re: Bit depth = levels of gradient?

filmrescue wrote:

Another poster suggested that the reason I sometimes get banding is because of noise and not because of bit depth when capturing very low contrast B&W negatives with a DSLR.

It's a lack of noise that gives contour banding. Lack in the original RAW digitization is possible, but only in the deepest shadows in or near base ISO of just a few cameras. Most contour banding comes from smoothing an image in post-capture processing.

You need noise up to a certain point, and only after that does it become problematic.

When using a camera to photograph the film, you generally want the one with the least noise; both high DR and high SNR18 at base ISO.  If your camera is not top-end there, you can take multiple exposures and stack them, and you can take things a step further and slightly move the film with each exposure and combine them in alignment software.  This will lose some of the spatially correlated noise that might be in a single capture, and resolve the grain a little better.

On a scanner, you can do the same thing.  Things that stand still for you, like a statue, building or film, allow you to build a better image than is possible in one exposure.  With the level of contrast push you seem to be talking about, eliminating all non-film artifacts can be very helpful.  This can get very computation-intensive though, if you do it right.

John Sheehy Forum Pro • Posts: 22,024
Re: I think you're getting misleading/unhelpful advice here

knickerhawk wrote:

filmrescue wrote:

I've been searching around to find some sort of chart or list that tells me how many levels of gradient there is for different single channel bit depths but I'm not having a lot of luck. Can anyone fill me in or link me to the info I'm looking for. I'd like to see from 2 all the way up to 20 or so.

Your problem isn't about too much noise in the deep shadows limiting the dynamic range of the image. Indeed, more noise would actually reduce the appearance of posterization/banding that you're seeing. And since you're scanning negatives and presumably inverting them to positives, most of the image noise should be present in the highlights, not the shadows, of the output image. The dithering effect of the noise should actually mask posterization, not make it worse. Noise is NOT the enemy here!

No, but excess noise is.  Most cameras have excess noise in most of their tonal ranges.  Ideal noise is equally distributed noise over a range of 1 DN, with no spatial correlation or low-frequency content at all.  Real noise is a bit worse than that, and mostly unnecessary.

57even Forum Pro • Posts: 13,718
Re: Bit depth = levels of gradient?

John Sheehy wrote:

filmrescue wrote:

Another poster suggested that the reason I sometimes get banding is because of noise and not because of bit depth when capturing very low contrast B&W negatives with a DSLR.

It's a lack of noise that gives contour banding. Lack in the original RAW digitization is possible, but only in the deepest shadows in or near base ISO of just a few cameras. Most contour banding comes from smoothing an image in post-capture processing.

You need noise up to a certain point, and only after that does it become problematic.

If the lightness difference of the tones is less than the JND we should not see any posterisation, even if there is no noise at all.

That would require about 9.5-10 bits at a display contrast of 800:1.

8-bit media devices are a bind. Prints are usually OK thanks to dither and a lower contrast range, but displays are a real issue, especially if you adjust contrast - even when the image has noise.

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John Sheehy Forum Pro • Posts: 22,024
Re: Bit depth = levels of gradient?

57even wrote:

8-bit media devices are a bind.

Especially with software-based integer color management.  It can really screw up non-noised gradients.  I almost puked when I looked at a greyscale gradient across the monitor years ago after I tried "correcting" the monitor in software.

OP filmrescue Contributing Member • Posts: 805
Re: Bit depth = levels of gradient?
2

Thanks John...Your arguments may have saved me at very least 5000.00. Going in today to try out the d850 on a copy stand with some negatives. Sounds like 14 bit is going to be more than adequate.

OP filmrescue Contributing Member • Posts: 805
Re: Bit depth = levels of gradient?

D Cox wrote:

filmrescue wrote:

bclaff wrote:

filmrescue wrote:

I've been searching around to find some sort of chart or list that tells me how many levels of gradient there is for different single channel bit depths but I'm not having a lot of luck. Can anyone fill me in or link me to the info I'm looking for. I'd like to see from 2 all the way up to 20 or so.

The answer is not simple and is not the answer you will typically receive.
For example, with most systems there is no visible difference between 14-bits and 12-bits; and certain ly a factor of 4 difference.

You may want to look at what DxOMark call "Tonal Range".

What exactly are you trying to accomplish.

Primarily to be able to talk intelligently about why to be using a high bit depth capture system when capturing extremely low contrast negatives.
Also to be able to calculate for instance, if the negative I'm capturing is occupying 5 percent of the tonal range from absolute black to absolute white, how many levels of gradient do I have to work with if I use a 16 bit scanner or high end camera vs a 12 bit or 14 bit camera and at what point can I expect to see posterization given the capture system.

The other numbers for other bit depths are primarily just because I was curious.

If you are talking about digitizing B&W negatives (silver based), my experience is that the crucial thing is to resolve the grain sharply. Low contrast negatives are not a problem. It's easy enough to adjust the white and black points in the image to give a full range of tones from what was a narrow band of pale greys.

The problem with low contrast negatives is that the signal-to-noise ratio is poor, so every speck of dust shows clearly. This is equally a problem in the darkroom, using traditional printing methods.

Any high resolution camera such as a Sony A7rii or a Sigma sdQH, with a good macro lens at its best aperture, will do the job.

High contrast originals such as most colour slides are a bigger problem. Some cameras have a built in HDR feature which is helpful. The new Panasonic full-frame cameras seem to have a very good dynamic range, but the high resolution model is extremely expensive.

Here's a very thin neg -- it was taken on some kind of ultra-fine-grain film -- and a positive result.

Thanks D Cox...the negatives that i"m dealing with are not like a normal low contrast negative where you actually with the naked eye easily see an image there. These are from recently processed lost and found film sometimes as old as from the 1920s. We just processed a film that expired in 1908 but that one somehow turn out comparatively okay. These are sometimes negatives that with the naked eye appear to have no image at all unless you look very closely over a very even light source. The opposite of the slide you're talking about where HDR can help.  That by the way was interesting info for me. I've never been able to get a digital camera to come even close to a film scanner with a slide because of highlights and shadows blocking up. I'll try that out.

OP filmrescue Contributing Member • Posts: 805
Re: Bit depth = levels of gradient?

WunWegWunDarWun wrote:

filmrescue wrote:

J A C S wrote:

filmrescue wrote:

Another poster suggested that the reason I sometimes get banding is because of noise and not because of bit depth when capturing very low contrast B&W negatives with a DSLR. I'm not fully understanding that though. The banding goes away when I scan it with an actual film scanner at 16 bit but maybe he's right and that's not a bit depth issue.

Why don't you post some scans. Who knows what your scanner is doing under the hood. It might not use your bits efficiently or it might convert to low quality JPEGs, etc.

My own scans show enough grain to think that posterization should not be a problem but on some of them, I do see posterization. Most likely a poor conversion (Nikon Coolscan 4000ED if I remember well, 14 bit).

BTW, the tonal range calculations are valid at a reference resolution for the highest frequencies only, roughly speaking. In large low frequency areas, like sky, etc., the extra bits might help.

Thanks Jacs...I'll try to do that tomorrow when that computer is back on the network here. I think I'm maybe worrying about it too much though because as another poster brought my attention to that with the extremely low contrast negatives that we're capturing, noise is overwhelming everything anyway when we try to bring things up to normal values and banding is only a small issue in comparison and relatively rare. It might be coming from something different than I thought it was.

We're just in the market for a new capture camera now so I was hoping to strike off the list one of the issues we sometimes see because we finally have a budget for something decent...up to 25,000 USD or so but if I can do it for a much smaller dollar amount I'll want to do that. The big dollars come with the 16 bit camera systems.
BTW...this needs to be done with a camera and not a scanner for a number of different reasons. To low contrast to marquee the frame, sometimes too dense for a scanner to see through the film and sometimes we need to capture film while it's under water...long explanation for that.

If you are only going to be digitizing 135 film check out a Nkon ES-2 digitzing adapter set, combined with a d850 and a suitable macro lens - you will have over $20k left and no film information will be lost.

I'm thinking now that the D850 is coming out on the top of my choices if I don't in fact need 16 bit for the absolute best quality. I already have the nikon 60mm macro lens, a copy stand and a lab grade transillumintor so won't be needing the ES-2

threw the lens
threw the lens Senior Member • Posts: 1,126
Re: Bit depth = levels of gradient?

Where bit depth really comes into its own is post processing.

It's been that way in other fields too. For instance a CD may "only" be 16 bits, but if you re mastering on the equivalent of a digital 8 track, 24 bits will be good to have, because you could be potentially summing the values of all those tracks and want some headroom for post processing.

You might not need more than 12 bit colour for a photo if you expose correctly for instance, but when you try to pull the effects sliders around in raw then you can run into artefacts at over 1 stop change in exposure.

D Cox Forum Pro • Posts: 23,886
Re: Bit depth = levels of gradient?

threw the lens wrote:

Where bit depth really comes into its own is post processing.

It's been that way in other fields too. For instance a CD may "only" be 16 bits, but if you re mastering on the equivalent of a digital 8 track, 24 bits will be good to have, because you could be potentially summing the values of all those tracks and want some headroom for post processing.

You might not need more than 12 bit colour for a photo if you expose correctly for instance, but when you try to pull the effects sliders around in raw then you can run into artefacts at over 1 stop change in exposure.

Software such as Photoshop does its calculations in 16-bit, even if the camera saved 12-bit files.

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