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Author Topic: Edit Tiff vs. Raw - what do I lose?  (Read 8796 times)
wolfnowl
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« Reply #20 on: September 19, 2011, 03:13:56 PM »
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So, from a practical standpoint, you are saying that some day some guy might jump from a tall building and... not fall to the ground?

Been done... Arthur Dent in 'The Hitchhiker's Guide to the Galaxy' series... book 4(?)  Actually he tripped and forgot to fall, so there's a different set of parameters again!  Grin

Mike.

(Just injecting a little levity)
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dmerger
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« Reply #21 on: September 19, 2011, 03:25:41 PM »
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So, from a practical standpoint, you are saying that some day some guy might jump from a tall building and... not fall to the ground?

I wouldn’t bet on it, and I wouldn’t want to be the guy doing the experiment, but ya never know.   Undecided

If I lived in the 1800’s and found someone willing to bet that Newton’s theory of gravity was wrong, I’d have bet everything I own.  Einstein would have put me in the poor house!   Ya never know.
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Chris Kern
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« Reply #22 on: September 19, 2011, 04:02:42 PM »
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DNG files produced b DxO Optics Pro are not really Raw files as the ones that come out of the camera. First, they have been interpolated and demosaiced, since that's the only way for DxO to apply the optical corrections.

[ ... ]

An important note is the way blown out highlights are treated when using this workflow: the resulting DNG don't have those highlight at saturation (equivalent to 255 in 8 bits) meaning that if you perform white balance in LR/ACR and then apply highlight recovery, your highlights may result non neutral. In this case you should perform white balance in DxO before producing the DNG.

More on this thread

Thanks for the reply and also to the link to your very interesting posts in the referenced thread.  (And to Andrew Rodney, who also pointed out that the DNGs produced by DxO don't encapsulate raw data.)

Chris
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digitaldog
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« Reply #23 on: September 19, 2011, 04:04:17 PM »
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The DxO folks don’t want to make that fact anything close to obvious <g>.
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Andrew Rodney
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Schewe
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« Reply #24 on: September 19, 2011, 05:01:19 PM »
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I want a plugin api in lightroom that allows 3rd party plugins to "hookin" to the pipeline at any given point, and do its thing on the fly.

If you mean plug-in to ACR processing pipeline, you'll have a really long wait. The ACR/LR works as well as it does because it's an unbroken pipeline completely under the control of the engineers. To open the pipeline up would hand over control of certain parameters to a 3rd party and I'm pretty darn sure Thomas Knoll would never do that.
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hjulenissen
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« Reply #25 on: September 19, 2011, 05:24:23 PM »
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If you mean plug-in to ACR processing pipeline, you'll have a really long wait. The ACR/LR works as well as it does because it's an unbroken pipeline completely under the control of the engineers. To open the pipeline up would hand over control of certain parameters to a 3rd party and I'm pretty darn sure Thomas Knoll would never do that.
I have no idea how mr Knoll and his collegues thinks about this.

But I fail to see why opening up the pipeline would be such a disaster from a technical/ergonomical point of view. From a sales/economic point of view it might, but that is not something that I am occupied with.

It could be made quite simple initially. Only one entry-point. Some well-defined format for i/o. If the right plugin is not found on the computer, it will simply be by-passed (and a more or less incompletely developed image is seen).

If you record music on your PC, there are standards for how plugins will work, and they are indeed "parametric" in that you can usually re-render the music in real-time at any time changing the parameters.

I do not see Lightroom as the ultimate raw processing pipeline, but a stable, intuitive, reasonably fast database that I have the confidence to spend hours importing my images into.

-h
« Last Edit: September 19, 2011, 05:25:54 PM by hjulenissen » Logged
dreed
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« Reply #26 on: September 19, 2011, 05:39:50 PM »
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A TIFF file is a rendered file as is a JPEG.

It's moderately well known that you cannot do white balance correction as effectively with a JPEG file as you can with a RAW file.

It therefore seems reasonable that a basic example of the limitation of TIFF vs RAW would be in white balance correction.

But that's something that you can do - once - prior to exporting the image.

Where you will lose editing quality is if you darken the RAW image at all in creating the TIFF.

The result of that will mean that colour information is thrown away that can never be reclaimed.

However the same holds true for generating any picture from data - once the data is transformed to make the image darker, you must go back to the original data to again lighten the image, you cannot use the rendered result even if the format stays the same (eg JPEG to JPEG.)
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Schewe
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« Reply #27 on: September 19, 2011, 05:44:00 PM »
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I have no idea how mr Knoll and his collegues thinks about this.

But I do and I'm telling you, the engineering required to open up the ACR/LR pipeline is simply not something that is likely to happen. Thomas and the boys are all about making the processing better within the pipeline but trying to hook up some other processing routine and not breaking the pipeline is a major deal. Everything that is processed within the pipeline is completely dependent upon the steps of the pipeline. Adding a 3rd party routine–and truth be told I've not yet heard a compelling reason yet–would make a complex pipeline even more complex and fragile...nope, sorry, not something I would want to see.
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madmanchan
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« Reply #28 on: September 19, 2011, 05:50:53 PM »
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Some tools work equally well and similarly in behavior between raw and non-raw; examples include tone curves, HSL tweaks, post crop vignette, and split tone. But others are really optimized for raw or the processing is of a nature such that the adjustment is fundamentally best done in raw space; examples includ white balance, color profiles, sharpening, noise reduction, and lens corrections. So, there is still useful capabilities when adjusting non-raw files like jpegs but overall, the more you can take care of starting from th raw file, the better.
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meyerweb
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« Reply #29 on: September 19, 2011, 05:55:06 PM »
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Thanks folks.  An interesting discussion. I may try that experiment when I get some time.  I know a few images alone won't be proof, but I figure if I try a high-key image, a low-key image, and a high-contrast image, and a variety of edits on each, it may tell me something.
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Schewe
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« Reply #30 on: September 19, 2011, 06:40:55 PM »
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So, there is still useful capabilities when adjusting non-raw files like jpegs but overall, the more you can take care of starting from th raw file, the better.

I would also add that a lot of the processing in ACR/LR for non-raw files really depends on the source of the file and what color space and gamma the rendered images are in. A camera JPEG that is sRGB or Adobe RGB will not fare as well in processing as a Photoshop 16 bit RGB image. The ACR/LR processing pipeline is based on doing the processing in it's own color space which is essentially ProPhoto RGB colors with a linear gamma in 16 bit. So the closer your rendered file would be to the pipeline, the better the processing of the image will be.

Look, processing an image inside of ACR/LR that started life elsewhere is still a useful strategy...arguably better than processing the file in Photoshop. But the closer that image is to raw, the better potential for corrections down the road.

If I were to rank the alternatives to raw, the 1st best alt would be a linear DNG. It's not restricted to a fixed color space and the linear gamma gives a lot of head room editing the extreme highlights (a benefit to raw). The next best would be a ProPhoto RGB in linear gamma, but that's not something that's easy to do...a ProPhoto RGB 16 bit would be a slight step down from ProPhoto Linear. Less good would be Adobe RGB 16 bit...the ARGB color space would clip potential colors and the gamma is already locked in at 2.2 so you would lose precision going from 2.2 to linear.

The worst source of files for editing in ACR/LR would be sRGB or Adobe RGB camera JPEGs...and it would be pretty low on the ladder compared to raw. But compared to opening an sRGB camera JPEG in Photoshop for editing, ACR/LR would still be a better processing pipeline.

I don't disagree that some 3rd party Lightroom plug-ins that render the raw file into a TIFF can be useful. The key point is at what point you go into the render format and why. If you've already done all the image corrections in ACR/LR and need a processing routine you can only get via the plug-in, go for it. You'll still have your original raw file you can go back to.

The vast majority of my images always remain in raw format. The only time I render a raw to a 16 bit ProPhoto RGB is to do those things that can only be done in Photoshop–and I always do this so I can soft proof and do final retouching prior to making serious prints. Note however, once I've rendered the image into Photoshop, I rarely go back and apply any Develop module image adjustments...
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bjanes
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« Reply #31 on: September 20, 2011, 09:03:31 AM »
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If I were to rank the alternatives to raw, the 1st best alt would be a linear DNG. It's not restricted to a fixed color space and the linear gamma gives a lot of head room editing the extreme highlights (a benefit to raw). The next best would be a ProPhoto RGB in linear gamma, but that's not something that's easy to do...a ProPhoto RGB 16 bit would be a slight step down from ProPhoto Linear. Less good would be Adobe RGB 16 bit...the ARGB color space would clip potential colors and the gamma is already locked in at 2.2 so you would lose precision going from 2.2 to linear.

Linear working spaces are used in Lightroom and ACR because white balance, demosaicing, and other processes performed by raw converters are best performed in a linear space. However, linear integer encoding is inefficient, since it wastes most of its range at the high end with a superfluous number of levels. Most of those levels can be thrown away with no perceptible damage to image quality, as is done with the Nikon compressed NEFs. The theoretical extra highlight headroom to which you refer is not attainable because the noise in the image is much greater than the quantization step (see Emil Martinec). The shadows in a linear integer encoding are impoverished and have a large quantization error as demonstrated by Figures 2 and 3 in Greg Ward's HDR paper. Raw files are not posterized, but excessive editing of shadow areas can result in posterization if the effect is not masked by noise. Some raw converters now use 32 bit floating point in their working spaces.

As Bruce explains and is quoted below, the size and shape of the gamut is not affected by gamma, but the quantization is. Bruce has determined that a gamma of 2.12 gives the least quantization error, and this is reasonably close to the gamma 2.2 in AdobeRGB and the average gamma in sRGB. A linear space is not ideal for editing, but using 16 bits does keep the quantization error relatively low.

Regards,

Bill


Bruce Lindbloom:

Gamma does not affect the size or shape of the gamut. It does affect the distribution of RGB points within the gamut. Therefore, it is an important consideration for controlling quantization. I have previously analyzed the optimal gamma for the grayscale only (you can see this analysis here). This result was about 2.2 (actually either 2.1723 or 2.3243 depending upon the error metric used).

For Beta RGB, I additionally performed a three-dimensional analysis, where I looked at the ΔE produced by tiny perturbations in RGB space, measured at each of the locations in the color set. For each color, the RGB value was perturbed a distance of one-percent in each of 20 different directions (I used the centers of the 20 faces of an icosahedron to evenly distribute the directions in three-space). Minimizing the RMS ΔE resulted in a gamma of 2.12. This was sufficiently close to 2.2 that I did not feel a deviation from a "standard" 2.2 value was warranted.
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stamper
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« Reply #32 on: September 20, 2011, 11:08:03 AM »
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So, from a practical standpoint, you are saying that some day some guy might jump from a tall building and... not fall to the ground?

Yes.....he might fall in the sea or a river. Wink Grin

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hjulenissen
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« Reply #33 on: September 20, 2011, 12:44:57 PM »
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The theoretical extra highlight headroom to which you refer is not attainable because the noise in the image is much greater than the quantization step (see Emil Martinec).
Thank you for that link, it was an interesting read.

-h
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madmanchan
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« Reply #34 on: September 20, 2011, 01:05:55 PM »
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Bill, fortunately the so-called linear DNG images don't actually have to be stored using linear integer representation. They can be stored using non-linear encoding if desired. (There are also some extensions in the works that will provide extra flexibility.)
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dmerger
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« Reply #35 on: September 22, 2011, 04:29:00 PM »
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I wouldn’t bet on it, and I wouldn’t want to be the guy doing the experiment, but ya never know.   Undecided

If I lived in the 1800’s and found someone willing to bet that Newton’s theory of gravity was wrong, I’d have bet everything I own.  Einstein would have put me in the poor house!   Ya never know.


Off topic for the thread, but a good example of "ya never know": "Physics rule broken? European scientists claim neutrinos measured traveling faster than light."  http://www.washingtonpost.com/world/europe/absolute-speed-barrier-broken-cern-claims-neutrinos-clocked-traveling-faster-than-light/2011/09/22/gIQA5Sn9nK_story.html?hpid=z2
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Dean Erger
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