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Author Topic: 16-bit DSLR  (Read 63272 times)
Henry Goh
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« on: November 29, 2007, 12:01:54 PM »
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What does it take to make 16-bit DSLRs?  How much more would it cost?  What are the restrictions if any?

Most people do not need to go beyond 10/12 Mp captures but they do need/want better renditions of tones and gradations.  I think I would love to have a 16-bit Nikon D3xx.  I'm not technically familiar as to what needs to go into the making of such a camera.  Anyone better equipped can share their knowledge?
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Panopeeper
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« Reply #1 on: November 29, 2007, 01:39:37 PM »
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Most people do not need to go beyond 10/12 Mp captures but they do need/want better renditions of tones and gradations.  I think I would love to have a 16-bit Nikon D3xx

Please explain, how you would utilize the 16-bit range, or, turning it around, when - in which situations - do you experience a lack of tones/graduations, with particular attention to the dynamic range of the envisioned camera.
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Graeme Nattress
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« Reply #2 on: November 29, 2007, 02:00:31 PM »
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I wouldn't say there's any problem with the tones and graduations on current cameras. Dynamic range can always be improved, and without such an improvement, a move to 16bit is not justified.

I've not seen an MF cameras properly tested for DR, but I highly doubt them capable of true 16bit performance.

Graeme
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Guillermo Luijk
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« Reply #3 on: November 29, 2007, 03:50:48 PM »
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Some brief comments:
- Dynamic Range: 16-bit RAW files by itlsef won't improve the dynamic range of a camera. DR is today limited by noise in the shadows, so if there is no noise improvement at the same time as upgrading from 12 to 14 or 16 bits, there will be no dynamic range expansion at all.

- Tonal quality (gradations): sometimes we forget most camera sensors have a Bayer pattern distribution, where 2/3 (i.e. 66.6%) of levels of a developed 12 bit RAW file, are interpolated straight in the 16 bit range. That doesn't mean they have more precision than the 12 bit samples (since they are interpolated from them) but it means they will take many more values in the huge 0..65535 range. This will make an upgrade from 12 or 14 to 16 bit RAW much les noticeable in terms of softer gradations.

- Photoshop is 15 bit, so if you feel happy using Photoshop and buy a 16 bit camera in the future, you must think PS will steal one bit from your image so you will be only 1 bit ahead of the recentrly introduced 14 bit cameras.

- Everytime more and more, storing RAW files is becoming a big problem. And since an increasing number of Mpx is the common trend, file sizes will get larger and larger. To store 16 bit images instead of 12 or 14 bit, with no apparent advantage in terms of image quality will not be a good business.


After saying all that, I am sure there will be 16-bit DSLR cameras in the near future    
« Last Edit: November 29, 2007, 03:53:18 PM by GLuijk » Logged

digitaldog
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« Reply #4 on: November 29, 2007, 03:54:20 PM »
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Some brief comments:
- Dynamic Range: 16-bit RAW files by itlsef won't improve the dynamic range of a camera. DR is today limited by noise in the shadows, so if there is no noise improvement at the same time as upgrading from 12 to 14 or 16 bits, there will be no dynamic range expansion at all.

If you say that, lots of people around here will argue that. I will not, I totally agree. The more I read, the more this gets reinforced in my mind (speaking of which, this is discussed as we both believe in a new book called The HDRI Handbook by Christian Bloch. Just started it, but its quite good and in the first chapter, he backs up this point).
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Andrew Rodney
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« Reply #5 on: November 29, 2007, 04:11:05 PM »
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- Photoshop is 15 bit, so if you feel happy using Photoshop and buy a 16 bit camera in the future, you must think PS will steal one bit from your image so you will be only 1 bit ahead of the recentrly introduced 14 bit cameras.
[a href=\"index.php?act=findpost&pid=157071\"][{POST_SNAPBACK}][/a]


Actually, it's 15 full bits plus one level, which is important (and why the engineers did it) relative to processing and so there would be an exact middle level.

I've seen and heard of scanners and cameras "claiming full 16 bit" and I think that's bogus. They may have something north of 14 bit but I think it would depend on what one would consider noise and signal. 15 bits of signal is more than plenty...
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AJSJones
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« Reply #6 on: November 29, 2007, 04:54:39 PM »
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What does it take to make 16-bit DSLRs?  How much more would it cost?  What are the restrictions if any?
[a href=\"index.php?act=findpost&pid=157007\"][{POST_SNAPBACK}][/a]

Henry - are you asking about whether 16-bit dynamic range from the sensor could be achieved, aka up to 16 stop range?  This would require the ability to read out very low photon counts from the deep shadows ,  adequately distinguished from read-out noise,  from a well in a pixel on the sensor (conceptually a photon bucket) with a capacity of 2^15 above that - that's a very big bucket, and the sensor manufacturers don't seem to be there yet.  Some read-out noise can be decreased by cooling the sensor (astro cameras do that) and well size can be increased by making bigger pixels. I'm sure the practical aspects of sensor fabrication/design to improve DR are carefully guarded and proprietary !
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John Sheehy
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« Reply #7 on: November 29, 2007, 05:39:02 PM »
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What does it take to make 16-bit DSLRs?  How much more would it cost?  What are the restrictions if any?

Most people do not need to go beyond 10/12 Mp captures but they do need/want better renditions of tones and gradations.  I think I would love to have a 16-bit Nikon D3xx.  I'm not technically familiar as to what needs to go into the making of such a camera.  Anyone better equipped can share their knowledge?
[a href=\"index.php?act=findpost&pid=157007\"][{POST_SNAPBACK}][/a]

A DSLR with 16 useful bits would be wonderful.  The problem seems to be that manufacturers don't seem to have any way of reading out the full range of the sensor (IOW, at the lowest ISO) without introducing a significant amount of electrical noise, so anything more than 12 bits is recording mostly noise at this point in technology.  Some readout technologies, like those used by Canon DSLRs and some of the newer Nikons can read out a lower range of sensor charges (IOW, high ISO) with less noise, relative to absolute signal.  The quality of 12-bit ISO 1600 RAW data from these cameras would do excellent as the lowest 12 bits of a 16-bit ISO 100; they have as little as about 15% of the noise added in the readout/digitization process at ISO 100, relative to absolute signal.

Canon and Nikon have just raised their bit depths to 14, and if you take these RAWs and replace the lowest two bits (which can be either '00', '01', '10', or '11')with '10', and perform torture tests on the data, and they don't seem to be any the worse for it.  The introduction of 14 bits is simply coinciding with other improvements in image quality, and gets undeserved credit, IMO.
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BernardLanguillier
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« Reply #8 on: November 29, 2007, 06:10:20 PM »
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If you say that, lots of people around here will argue that. I will not, I totally agree. The more I read, the more this gets reinforced in my mind (speaking of which, this is discussed as we both believe in a new book called The HDRI Handbook by Christian Bloch. Just started it, but its quite good and in the first chapter, he backs up this point).
[a href=\"index.php?act=findpost&pid=157073\"][{POST_SNAPBACK}][/a]

Why would someone argue with this?

The definition of DR depends very much on the way noise in the shadows is measured right?

Bit depth has nothing to do with DR. You can capture an amazing B&W 50 stops perfect gradient with an 8 bits sampling, the transitions will just not be smooth if you have an image with more than 255 pixels. You will get banding.

Cheers,
Bernard
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digitaldog
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« Reply #9 on: November 29, 2007, 06:18:29 PM »
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Why would someone argue with this?

http://luminous-landscape.com/forum/index....27&hl=staircase
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Andrew Rodney
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bjanes
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« Reply #10 on: November 29, 2007, 06:39:17 PM »
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Why would someone argue with this?

The definition of DR depends very much on the way noise in the shadows is measured right?

Bit depth has nothing to do with DR. You can capture an amazing B&W 50 stops perfect gradient with an 8 bits sampling, the transitions will just not be smooth if you have an image with more than 255 pixels. You will get banding.

Cheers,
Bernard
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Bernard,

With linear integer encoding, dynamic range is limited by the bit depth as shown by the [a href=\"http://www.normankoren.com/digital_tonality.html]table[/url] on Norman Koren's web site. The table shows that 10 bits can encode only 10 stops, and that allows only one level in the darkest f/stop. You would really need more to avoid banding.

The trouble with linear integer encoding is that it devotes more bits than needed to the brighter stops than to the darker stops. Gamma encoding at 2.2 improves the distribution somewhat.
« Last Edit: November 29, 2007, 06:39:49 PM by bjanes » Logged
Panopeeper
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« Reply #11 on: November 29, 2007, 07:12:59 PM »
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Tests of the human eye's ability to distinct between shades show, that one can distinguish between two shades if their lightness differes at least 1% (I guess this is a rounded value.)

Consequently, we can distinguish between at least 70 levels within one stop dynamic range (2^70 = 2.00...). In order to eliminate visible transitions, the number of levels needs to be higher. I don't know how high and I am cautios to accept anything, which is not based on tests of a wide range; I remember to have been told, that 24 frames per second are all needed, for we don't "see" anything above it.

Anyway, let's accept this 70 as an initial value. Select the one stop wide range of the lowest lightness, which needs "full service", i.e. all levels. From here above every further stop requires twice as many levels because of the linearity of the sensor.

Accordingly, 10 stop "clean" dynamic range requires 70*2^9 = 35840 levels. Add to this the number of levels, which are required for the "dirty" stops (there is not much point to distinguish between 70 levels of a noisy stop).

This range requires over 15 bits, and the dynamic range is still not very large.

However, what does one do with such an image file?

The consideration, how many bits Photoshop can handle it totally irrelevant. Not only, because Photoshop is not the center of the universe, but because the software will support much greater bit depth as soon as it becomes actual.

But how does one present such image? I don't know what is on the horizon of printer development, but the monitors are not far away from reproducing not 12 but 16 stops. Some consumer grade monitors offer already contrast ratio 3000:1 (ok, that's a claim,. but I guess that is at least 2000:1), and new development promises tens of thousands of contrast ratio. These monitors (even those with 3000:1) are not for computer work but video (the resolution is not high enough for example for image processing), but that too is only a question of demand - and anyway, why could not images be presented on TV monitors?

The new JPEG standard will handle such images, so we only need cameras with higher dynamic range.

As the dynamic range is not limited by the noise in shadow but by the well capacity (the former is the consequence of the latter), we only need less pixels on the same sensor with the newest technology. Unfortunately, misguided consumer considerations force manufacturers to cram more and more pixels on the sensor.

Any time I hear people talking about digital cameras, the first question is always "how many megapixels". We should start an action to disspell the myth, that the measure of camera's quality is the number of pixels.
« Last Edit: November 29, 2007, 07:14:54 PM by Panopeeper » Logged

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bjanes
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« Reply #12 on: November 29, 2007, 07:41:21 PM »
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Some brief comments:
- Dynamic Range: 16-bit RAW files by itlsef won't improve the dynamic range of a camera. DR is today limited by noise in the shadows, so if there is no noise improvement at the same time as upgrading from 12 to 14 or 16 bits, there will be no dynamic range expansion at all.
[{POST_SNAPBACK}][/a]

Data are starting to dribble out on the performance of the new Canon and Nikon sensors with 14 bit ADCs.

[a href=\"http://theory.uchicago.edu/~ejm/pix/20d/posts/tests/D300_40D_tests/]Emil Martinec[/url], professor of physics at the University of Chicago, has published data for the Nikon D300 and Canon 40D. He uses the engineering definition of DR (dynamic range = raw saturation level divided by read noise). At base ISO both cameras have a DR of about 11.3 stops, and gain about 1/3 of a stop when going from 12 bit to 14 bit mode. It would appear that 12 bits would be sufficient for these cameras.

EJ Martin, also at the U of C, reported results for the Nikon D3. He found a DR of 11.7 f/stops. Since the D3 pixel size is considerably larger than that of the D300 or 40D, one would expect a better DR with the D3 if read noise is held to the same level, since DR = full well capacity/read noise.

These gains in DR are rather modest when compared with Roger Clark's prediction of a 2 stop gain for a properly implemented 14 bit camera as compared to 12 bits.
« Last Edit: November 29, 2007, 07:47:03 PM by bjanes » Logged
Henry Goh
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« Reply #13 on: November 29, 2007, 08:10:03 PM »
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Thanks guys.  You make such a wonderful resource center  

So at the end of the day, will I get an image with better tonal range if they made the camera I'm asking for here?  Is it coming anytime soon?
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bjanes
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« Reply #14 on: November 29, 2007, 08:18:59 PM »
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Tests of the human eye's ability to distinct between shades show, that one can distinguish between two shades if their lightness differes at least 1% (I guess this is a rounded value.)

Consequently, we can distinguish between at least 70 levels within one stop dynamic range (2^70 = 2.00...). In order to eliminate visible transitions, the number of levels needs to be higher.

Anyway, let's accept this 70 as an initial value. Select the one stop wide range of the lowest lightness, which needs "full service", i.e. all levels. From here above every further stop requires twice as many levels because of the linearity of the sensor.

Accordingly, 10 stop "clean" dynamic range requires 70*2^9 = 35840 levels. Add to this the number of levels, which are required for the "dirty" stops (there is not much point to distinguish between 70 levels of a noisy stop).

This range requires over 15 bits, and the dynamic range is still not very large.
[{POST_SNAPBACK}][/a]

The above line of reasoning is similar to that reported by [a href=\"http://www.normankoren.com/digital_tonality.html]Norman Koren[/url]; however, he states that fewer levels are needed in the darker zones, where the eye is less sensitive. Norman bases his calculations on the Weber-Fechner law, which dates to the mid 19th century, and has been replaced by the Steven's law. It would be interesting to repeat the calculations using the newer law.

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However, what does one do with such an image file?

The consideration, how many bits Photoshop can handle it totally irrelevant. Not only, because Photoshop is not the center of the universe, but because the software will support much greater bit depth as soon as it becomes actual.

But how does one present such image? I don't know what is on the horizon of printer development, but the monitors are not far away from reproducing not 12 but 16 stops. Some consumer grade monitors offer already contrast ratio 3000:1 (ok, that's a claim,. but I guess that is at least 2000:1), and new development promises tens of thousands of contrast ratio. These monitors (even those with 3000:1) are not for computer work but video (the resolution is not high enough for example for image processing), but that too is only a question of demand - and anyway, why could not images be presented on TV monitors?
[{POST_SNAPBACK}][/a]

[a href=\"http://www.dolby.com/promo/hdr/technology.html]BrightSide[/url] produces a monitor with a claimed 200,000:1 contrast ratio (17.6 f/stops) at a resolution of 1,920 x 1,080 on a 37 inch screen.

Photoshop can handle such images using 32 bit floating point representation (HDR). However, rendering such a contrast ratio into a printer space is problematic, and the full range of Photoshop tools are not available with 32 bit floating point representation.

Bill
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Panopeeper
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« Reply #15 on: November 29, 2007, 08:29:03 PM »
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BrightSide produces a monitor with a claimed 200,000:1 contrast ratio (17.6 f/stops) at a resolution of 1,920 x 1,080 on a 37 inch screen

With the high Canadian dollar, this a consumer grade monitor (only US$45,000); however, only 1080pix high sucks, so I rather stick to the Samsung 24" 244T, contrast ratio 1000:1 (claimed).
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« Reply #16 on: November 29, 2007, 08:37:17 PM »
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I've seen and heard of scanners and cameras "claiming full 16 bit" and I think that's bogus. They may have something north of 14 bit but I think it would depend on what one would consider noise and signal. 15 bits of signal is more than plenty...
[{POST_SNAPBACK}][/a]

[a href=\"http://www.dalsa.com/sensors/products/productdetails.asp?productID=FTF5066c]Dalsa[/url] and Kodak both publish the DR of their sensors used in medium format backs, and the typical DR is 70-72 db, or about 12 f/stops. Even though they may have 16 bit ADCs, the least significant bits most likely consist largely of noise, so 15 bits should be more than adequate, as you say. I have no data on scanners or scanning backs.

Bill
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BernardLanguillier
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« Reply #17 on: November 29, 2007, 09:53:58 PM »
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Bernard,

With linear integer encoding, dynamic range is limited by the bit depth as shown by the table on Norman Koren's web site. The table shows that 10 bits can encode only 10 stops, and that allows only one level in the darkest f/stop. You would really need more to avoid banding.
[a href=\"index.php?act=findpost&pid=157114\"][{POST_SNAPBACK}][/a]

Yes, of course, but this only has to do wit banding.

I am not saying that you can cover a 50 stops DR with 8 bits for practical applications, but my example is just about showing that there is no relationship between DR and bit depth.

Cheers,
Bernard
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bjanes
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« Reply #18 on: November 29, 2007, 10:17:15 PM »
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Yes, of course, but this only has to do wit banding.

I am not saying that you can cover a 50 stops DR with 8 bits for practical applications, but my example is just about showing that there is no relationship between DR and bit depth.

Cheers,
Bernard
[a href=\"index.php?act=findpost&pid=157151\"][{POST_SNAPBACK}][/a]

Bernard,

No, you can not cover 50 stops with 8 bit linear integer coding at all. The first stop would have 128 levels, the 2nd 64, the 3rd 32... down to the 8th where you would have one level. You can't go any darker because you've run out of values. The DR of 8 bit linear encoding is 8 f/stops. If you use gamma 2.2 encoding, then you can do better. Did you look at Norman's table?

Regards

Bill
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Panopeeper
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« Reply #19 on: November 29, 2007, 11:22:25 PM »
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there is no relationship between DR and bit depth

Sometimes I state in a discussions, that a digital image does not have any dynamic range; some people are outraged to hear that.

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you can not cover 50 stops with 8 bit linear integer coding at all. The first stop would have 128 levels, the 2nd 64, the 3rd 32... down to the 8th where you would have one level. You can't go any darker because you've run out of values. The DR of 8 bit linear encoding is 8 f/stops

You can cover a range of 50 stops even with one bit. Of course some stops will not be distinguishable from others (a kind of "posterization"), but so what? The stop is an artificial unit. What is the "natural meaning" of a stop in conjunction with scanned data or with any non-photographic digital image?

There is an uncountable number of intensities within any given stop, which are not distinguishable from each other. The "stop" is only a point on that scale.

For example a monitor's dynamic range will not be measured in stops but in the ratio of intensity between the brightest and darkest levels. The contrast ratio of 1000:1 does not imply any number of required levels.
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