Luminous Landscape Forum
Raw & Post Processing, Printing => Digital Image Processing => Topic started by: Sigi on April 21, 2009, 04:31:40 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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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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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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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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Dude!! Good one!!!
Todd in Chicago
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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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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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/ (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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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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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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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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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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Nen, qué nivelazo de inglés que tienes. Em deixes flipat
ai xiquet, aixó va a dies!
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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: 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...
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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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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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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/ (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.
(http://img528.imageshack.us/img528/6568/badnowgood.jpg) (http://img528.imageshack.us/my.php?image=badnowgood.jpg)
Jacopo
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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/ (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?
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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 (http://www.guillermoluijk.com/tutorial/zeronoise/index.htm). 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 (http://www.guillermoluijk.com/article/superhdr/index.htm) 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:
(http://www.guillermoluijk.com/tutorial/hdr/resultadolite9.jpg)
16-bit vs 8-bit postprocessing (posterization in the wooden table left and chair back when initial image was 8-bit):
(http://img26.imageshack.us/img26/2874/samplezbg.jpg)
For those interested in looking at the curves applied: capas.tif (http://www.guillermoluijk.com/misc/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
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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.
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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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.
What's a "normal" gamut, what's normal about Adobe RGB (1998) and what's an abnormal gamut?
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...
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
....
I know it's quite a extreme postprocessing, but just an example that I REALLY NEED 16 BIT for my interiors workflow.
BR
Thanks for an interesting example, BR.
Your work-flow strikes me as an adaptation of expose for the shadows, develop for the highlights approach. Although you do not show it in your crop, there is important highlight detail and tonality in the ceiling lighting. I think your image, in the context of your workflow, does make the case for 16 bit as a container for HDR processing.
It seems to me that, since your exposure covers 4 "bits" of dynamic range, it might be possible to get a similar banding effect in the shadows with a single shot, again staying in Adobe RGB.
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Your work-flow strikes me as an adaptation of expose for the shadows, develop for the highlights approach. Although you do not show it in your crop, there is important highlight detail and tonality in the ceiling lighting. I think your image, in the context of your workflow, does make the case for 16 bit as a container for HDR processing.
This somewhat strange workflow is because I feel comfortable editing images straight from a neutral RAW development (i.e. all parameters set to 0), so I am not interested at all in all those sliders commercial RAW developers have to offer.
By doing so all images behave the same to me and I know what to expect. I can process them usually with two curves in Photoshop (bright and contrast) with little or no manual edition.
Actually the exposure is for the highlights: I do ETTR in the scene to preserve the highest lights I am interested in, and make that shot be the least exposed in the {-2,0,+2} bracketing. Then the blending program uses DCRAW for RAW development, and that means neutral output. The only way to preserve all DR captured and in a totally virgin image, is to adapt output exposure to the least exposed shot, so any information coming from the most exposed shots is corrected down in exposure.
Anyway the resulting image in 16 bit is so powerful that several copies of it can be produced at different overexposed values and then blended in any HDR program supporting TIFF files. It will not be fake HDR since all the DR was into the output TIFF.
BR
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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 (http://www.guillermoluijk.com/tutorial/zeronoise/index.htm). 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 (http://www.guillermoluijk.com/article/superhdr/index.htm) 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:
(http://www.guillermoluijk.com/tutorial/hdr/resultadolite9.jpg)
16-bit vs 8-bit postprocessing (posterization in the wooden table left and chair back when initial image was 8-bit):
(http://img26.imageshack.us/img26/2874/samplezbg.jpg)
For those interested in looking at the curves applied: capas.tif (http://www.guillermoluijk.com/misc/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
HDR.
Yes I know it, floating point not integers (16 bit)!
After the tonal compression you can go for 8 bit. That is what I do, but the same is true for any researcher I know (Reinhard, Fattal, Drago, Ward,Tumblin,.... and so on),
But just to avoid confusion: 8 vs 16 bit is the image bit depth. Depending on algorithms the internal computations may be done with different numeric precision.
Just to give some example:
- going to CIE_Lab or CIE_XYZ for white balance is well performed using floating point (I use double precision!).
- transformations between color gamuts is internally performed in double (you have to go to/from XYZ or Lab, the PCS)
Jacopo
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Guillermo, interesting point focusing on shadows that need some heavy processing. I must say though that I have problems to perceive the differences in the crops you show.
Another experiment, I am not sure what point will support, it demonstrates that there's difference but I am not sure if that difference is perceivable. Anyway this case it is a single, very ordinary operation.
From this image: (http://jtrujillo.net/digital-photo-tutorials/8vs16bit/walkrs.jpg)
Loaded two copies of that same image one in 8 and the other at 16 bit mode. I applied Unsharp mask 300 / 0.3 / 4 to both.
Overlapped one on top of the other as a layer and put the layer mode to difference. Everything black.
But on top I've placed a Levels layer and moved the white point to the left, almost to the location of black. The result:
(http://jtrujillo.net/digital-photo-tutorials/8vs16bit/walkrs-dif.jpg)
This shows that there's significant information different between both images, you can recognize an image there!.
As I said I am not sure if it's perceivable at least consciously but I wonder if it might affect perhaps the outcome of a print?
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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.
Try http://www.visual-vacations.com/Photography/16_vs_8.htm (http://www.visual-vacations.com/Photography/16_vs_8.htm)
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Try http://www.visual-vacations.com/Photography/16_vs_8.htm (http://www.visual-vacations.com/Photography/16_vs_8.htm)
One of the reasons that 8 bit works so well is gamma encoding. Take that away, and there are a host of examples where 8 bit is inferior to 16 bit. The example you refer to, being a linear encoded image, shows the importance of this.
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The benefit of 16-bit workflow becomes obvious when applied to any image where aggressive level or curve adjustments are needed, not just linear-to-gamma-encoded tone curve conversion. Have you ever tried editing an underexposed JPEG vs a similarly underexposed RAW image? The shadow artifacts you'll find in the JPEG image vs the RAW are similar to those shown in my example. The same principle is true where the camera can barely capture all of the DR of the subject; working the image in 16-bit mode will give you cleaner shadow detail than an 8-bit version. The more aggressive the adjustment an image needs, the more beneficial 16-bit editing becomes.
Here's another example:
8-bit image file (http://www.visual-vacations.com/images/2009/2009-05-05_0003-8.tif)
16-bit image file (http://www.visual-vacations.com/images/2009/2009-05-05_0003-16.tif)
Process the 16-bit image in your usual manner, recording what you do to an action. The only rule is that you must stay in 16-bit mode from start to finish.
Run the action you just recorded on the 8-bit image, so that all steps are performed in 8-bit mode.
Compare the images side-by-side, and post the results.
Which image has the best shadow detail?