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Author Topic: 16 bit vs. 8 bit  (Read 9461 times)
Sigi
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« on: April 21, 2009, 03:31:40 AM »
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Hi,

If I run a picture through DXO I can save it as 8 bit or 16 bit tiff's. If I am 100% certain that I will not photoshop the picture but print it the way it is created by DXO do I have any advantage or maybe even disadvantage of saving in 16 bit?

Thanks

Sigi
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madmanchan
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« Reply #1 on: April 21, 2009, 08:06:32 AM »
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I would keep it at 16-bit. The only downsides to 16-bit files vs 8-bit files are speed (they take longer to open, copy, process, etc.) and size. There is a small advantage even if plan no further edits. Final color conversion to the printer drive space can make better use of 16-bit ICC color profile data. Some printer drivers and print paths support 16-bit printing.
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digitaldog
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« Reply #2 on: April 21, 2009, 08:14:33 AM »
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Unless you like to live on the edge, charge by the hour or have a really, really slow machine, its usually not recommended that you throw away data you can never recover again. So yes, keep it in 16-bit.
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Andrew Rodney
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Guillermo Luijk
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« Reply #3 on: April 21, 2009, 03:35:10 PM »
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What madmanchan and digitaldog said is totally wrong. According to the findings of an imaging expert (Dan Margulis), an 8-bit pipeline will suffice any demanding photographic edition and it's a waste of time and resources using 16-bit.

OK was just a joke. This forum becomes too serious sometimes    

Regards.
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Tklimek
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« Reply #4 on: April 21, 2009, 04:28:19 PM »
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Dude!!  Good one!!!

Todd in Chicago

Quote from: GLuijk
What madmanchan and digitaldog said is totally wrong. According to the findings of an imaging expert (Dan Margulis), an 8-bit pipeline will suffice any demanding photographic edition and it's a waste of time and resources using 16-bit.

OK was just a joke. This forum becomes too serious sometimes    

Regards.
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David Sutton
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« Reply #5 on: April 21, 2009, 04:31:15 PM »
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curvemeister
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« Reply #6 on: April 22, 2009, 01:37:33 AM »
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If you work in ProPhoto RGB, or another wide gamut space, there is a decided need for 16 bit.  

In other color spaces, such as Adobe RGB or sRGB, you are very unlikely to see a difference.  Personally I'm still waiting for a convincing example.  There are any number of excellent photographers who do not feel the need for an example, and decide to work in 16 bit simply to play it safe.  

Whichever choice you make, obviously, hold on to your original raw file.

Dan Margulis is absolutely worth reading, if you have not done so already.  He has ruffled many feathers, but his writing is entertaining and informative, and studded with many examples.

All the best.
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Mike Russell - www.curvemeister.com
jtrujillo
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« Reply #7 on: April 22, 2009, 05:06:19 AM »
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This is an easy to do experiment to see by yourself how can affect editing in 8 bit mode (an exaggerated processing to make it obvious but it shows the effect clearly)

http://jtrujillo.net/digital-photo-tutorials/8vs16bit/

I confess that at times I do my edits in 8 bit mode but I am aware that it can have some consequences in the outcome and when I foresee some heavy calculations an alarm rings
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Czornyj
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« Reply #8 on: April 22, 2009, 05:07:49 AM »
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Quote from: curvemeister
In other color spaces, such as Adobe RGB or sRGB, you are very unlikely to see a difference.

What printer has sRGB or AdobeRGB color space?
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Guillermo Luijk
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« Reply #9 on: April 22, 2009, 05:38:11 AM »
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Quote from: jtrujillo
I confess that at times I do my edits in 8 bit mode but I am aware that it can have some consequences in the outcome and when I foresee some heavy calculations an alarm rings

Nen, qué nivelazo de inglés que tienes. Em deixes flipat  
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digitaldog
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« Reply #10 on: April 22, 2009, 07:53:04 AM »
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Quote from: curvemeister
If you work in ProPhoto RGB, or another wide gamut space, there is a decided need for 16 bit.

Do you have documents and step by step editing processes that reveal this?
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Andrew Rodney
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« Reply #11 on: April 22, 2009, 07:54:12 AM »
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Quote from: Czornyj
What printer has sRGB or AdobeRGB color space?

None. Both are theoretical color spaces based on emissive displays (they are using an emissive reference media).
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Andrew Rodney
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jtrujillo
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« Reply #12 on: April 22, 2009, 09:08:02 AM »
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Quote from: GLuijk
Nen, qué nivelazo de inglés que tienes. Em deixes flipat  
ai xiquet, aixó va a dies!  
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Czornyj
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« Reply #13 on: April 22, 2009, 09:11:28 AM »
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Quote from: digitaldog
None. Both are theoretical color spaces based on emissive displays (they are using an emissive reference media).

That was rethorical question

In other words - when curvemeister says:
Quote from: curvemeister
In other color spaces, such as Adobe RGB or sRGB, you are very unlikely to see a difference
it seems, he's only referring to the situation on the display...
« Last Edit: April 22, 2009, 09:12:26 AM by Czornyj » Logged

curvemeister
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« Reply #14 on: April 22, 2009, 03:30:31 PM »
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Quote from: digitaldog
Do you have documents and step by step editing processes that reveal this?

Actually, I had your own examples in mind when I said this.  

You posted an example a year or two ago - a swatch of blue sky - that showed banding, and another image I believe with shadow detail that did better in 16 bit mode.  Both showed a clearly better result in 16 bit ProPhoto.
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Mike Russell - www.curvemeister.com
digitaldog
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« Reply #15 on: April 22, 2009, 03:37:09 PM »
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Quote from: curvemeister
Actually, I had your own examples in mind when I said this.  

You posted an example a year or two ago - a swatch of blue sky - that showed banding, and another image I believe with shadow detail that did better in 16 bit mode.  Both showed a clearly better result in 16 bit ProPhoto.


OK, cool. I was hoping for additional references.
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Andrew Rodney
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jbrembat
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« Reply #16 on: April 22, 2009, 03:38:46 PM »
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Quote from: jtrujillo
This is an easy to do experiment to see by yourself how can affect editing in 8 bit mode (an exaggerated processing to make it obvious but it shows the effect clearly)

http://jtrujillo.net/digital-photo-tutorials/8vs16bit/

I confess that at times I do my edits in 8 bit mode but I am aware that it can have some consequences in the outcome and when I foresee some heavy calculations an alarm rings

The introduction is for graphics not for photographers. You have to take in account noise.

I don't know what you was able to do in the real example, but I was able to recover it in 8bit mode in few seconds.





Jacopo
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curvemeister
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« Reply #17 on: April 22, 2009, 03:44:13 PM »
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Quote from: jtrujillo
This is an easy to do experiment to see by yourself how can affect editing in 8 bit mode (an exaggerated processing to make it obvious but it shows the effect clearly)
http://jtrujillo.net/digital-photo-tutorials/8vs16bit/
<snip>

This easy experiment does demonstrate that 16 bits is more bits than 8 bits.  A similar experiment could also show that 32 bits is more than 16, 64 more than 32, etc.  What I seek would be an image that shows that 16 bit editing has a clear advantage, when working in a normal gamut RGB space, such as Adobe RGB.

For example:  A picture of a building, with darkened windows, in Adobe RGB in 16 and 8 bit mode, either straight from the camera or from a RAW processor with vanilla settings.  In 16 bit, you can use curves or levels to light up the windows to see the interior of the house.  In 8 bit mode, you can't get at that detail, because it is lost.  Anyone have an example like that?
« Last Edit: April 22, 2009, 03:45:27 PM by curvemeister » Logged

Mike Russell - www.curvemeister.com
Guillermo Luijk
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« Reply #18 on: April 22, 2009, 04:11:42 PM »
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Quote from: curvemeister
What I seek would be an image that shows that 16 bit editing has a clear advantage, when working in a normal gamut RGB space, such as Adobe RGB.
(...)
Anyone have an example like that?

I have.

I usually shoot HDR interiors by blending 3 bracketed images {-2,0,+2} corrected to initially have the same exposure as the least exposed shot, i.e. a very dark image. I then open it into PS and apply a lift curve, a contrast curve, and some local arrangements when needed.

The initial image is obtained in 16-bit and Adobe RGB with 2.2 gamma using Zero Noise. That image needs to be very robust because shadows will be strongly lifted for tone mapping.

In 16-bit, these images are incredibly robust (I managed to lift here one of them by +12 EV, see Fig. 11, and there was no posterization. Not even a 16-bit linear DNG would have resisted such an overexposure, see Fig. 12). The trick for that is that both exposure correction and 2.2 gamma are applied at the same time, in just one high precission floating point operation, then rounded to 16-bit integer (BTW real 16-bit, not 15-bit like in Adobe software), so it's impossible to have a richer image for that degree of exposure.

On the contrary in 8-bit, the resulting image shows clear posterization in the shadows after the tone mapping process in PS. These images are almost noise free thanks to the optimum bracketed blending, so shadow posterization becomes easily visible on a low bitdepth:

Sample scene:


16-bit vs 8-bit postprocessing (posterization in the wooden table left and chair back when initial image was 8-bit):


For those interested in looking at the curves applied: capas.tif.

I know it's quite a extreme postprocessing, but just an example that I REALLY NEED 16 BIT for my interiors workflow.

BR
« Last Edit: April 22, 2009, 04:27:57 PM by GLuijk » Logged

jtrujillo
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« Reply #19 on: April 22, 2009, 04:19:03 PM »
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Quote from: jbrembat
The introduction is for graphics not for photographers. You have to take in account noise.

I don't know what you was able to do in the real example, but I was able to recover it in 8bit mode in few seconds.
Great but I still do not see a smooth gradient as in the result from 16bits. If that example were something with details in I suspect it would take some more seconds.

Quote from: curvemeister
A picture of a building, with darkened windows, in Adobe RGB in 16 and 8 bit mode, either straight from the camera or from a RAW processor with vanilla settings. In 16 bit, you can use curves or levels to light up the windows to see the interior of the house. In 8 bit mode, you can't get at that detail, because it is lost. Anyone have an example like that?
I don't think there's such image. The use of 16bit mode is for heavy duty calculations where truncation may lead to loss of visible information. I think that in a case as what you say, a single curve would have the same result in 8 or in 16 bits (Hey but me too would be happy to see some example proving the contrary, I am not advocating 16bits-forever, only in some cases or always to be on the safe side)
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