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Photo Retouching "Improving" photos, post-production, correction, etc.

is it better to start retouch with a flat image?

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  #41  
Old 04-12-2015, 09:50 AM
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andrewrodney andrewrodney is offline
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Re: is it better to start retouch with a flat imag

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Originally Posted by skoobey View Post
It all comes down to the fact that we can't produce color as nature can, and have come up with a work around, and hence all the trouble, and I don't think it'll change soon
Nature doesn't produce color, our brains do. Color isnít a particular wavelength or property of light, it is a cognitive perception. Color, is a perceptual property, something that occurs deep inside our brains. So if we can't see it, it is not a color. As such, colors are defined based on perceptual experiments.
Computers and digital cameras and scanners don't know anything about color either. They only 'know' about device values (numbers).
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  #42  
Old 04-12-2015, 02:10 PM
skoobey skoobey is offline
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Re: is it better to start retouch with a flat imag

Aha, and our brains aren't part of the nature?

Reasons why reality can't be replicated in current technogly:
screens emit light=they can't reproduce things that don't emit light(we will know we are looking at the screen, and not the real thing, and yes thre is the 3d aspect, but if you look wit one eye and don't move your head or the eye, you'll still know it's a screen).
printed colors and paints can't accurately reproduce other properties such as translucence.

It's a complex subject, and the reason I wrote that is because we just need to relax and enjoy our work with technology we are offered.
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  #43  
Old 04-12-2015, 02:28 PM
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Re: is it better to start retouch with a flat imag

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Originally Posted by skoobey View Post
Aha, and our brains aren't part of the nature?
A dogís brain is part of nature, it doesnít see color as we do so lumping everything into nature doesnít really mean anything when human color perception, part of the topic discussed, is a perceptual attribute of humans!

Quote:
Reasons why reality can't be replicated in current technogly:
Lets skip reality and stick with color and why the technology can fail us. For example, digital cameras can record ďcolorsĒ we canít see (and are thus not colors), we can see colors it canít record. Want to go into metameric failure? What about optical illusions like this: http://upload.wikimedia.org/wikipedi...ange_brown.svg

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It's a complex subject, and the reason I wrote that is because we just need to relax and enjoy our work with technology we are offered.
Yes it is a complex subject. For some, itís useful to know when technology will fail us. Itís like the statement:

If your clients are happy with results, and you are happy with your pay, who cares have you stared with flat conversion, or contrasty conversion, or no image at all.

True if you want to avoid workflow in the discussion. And thatís OK. But for some here, workflow and technological pitfalls are useful to understand and discuss and we do care.
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  #44  
Old 04-12-2015, 02:45 PM
klev klev is offline
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Re: is it better to start retouch with a flat imag

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Originally Posted by andrewrodney View Post
Well at least in the ACR engine, that doesnít have to be so, itís processing color space uses ProPhoto RGB primaries with a 1.0 TRC, you can encode in ProPhoto RGB itself or, itís rather simple to create a ProPhoto RGB 1.0 TRC profile out of Photoshop, select that in ACR and be done.
I lost my previous response. I was going to see what that would generate. My suspicion is that it wouldn't work so well, because you're still bound by encoding. 16-bit in photoshop uses an unsigned integer encoding, which differs from what is used in ACR / Lightroom on raw images. Otherwise I suspect you would have seen workflow updates in producing spherical HDRis commonly used for light CG objects that need to be added to either footage or still scenes.

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Originally Posted by andrewrodney View Post
He being Dan? No, heís totally confused by the product and doesnít understand how it functions or how it works. He stated many years ago ďitís unfit for professional useĒ. See Jeff Scheweís text:http://forum.luminous-landscape.com/...4234#msg624234
I didn't mean Dan. I meant captain hook here.

Quote:
Originally Posted by skoobey View Post
Aha, and our brains aren't part of the nature?

Reasons why reality can't be replicated in current technogly:
screens emit light=they can't reproduce things that don't emit light(we will know we are looking at the screen, and not the real thing, and yes thre is the 3d aspect, but if you look wit one eye and don't move your head or the eye, you'll still know it's a screen).
printed colors and paints can't accurately reproduce other properties such as translucence.

It's a complex subject, and the reason I wrote that is because we just need to relax and enjoy our work with technology we are offered.
Hmm? You are a little confused. When it comes to measured and quantified colors, they are based on light returned. This means with reflective media, the light source has to be quantified in addition to the medium and pigments. With emissive devices such as displays, it's just whatever is emitted by the display as reflections can't be completely controlled. Printed colors have many issues, one of which is that their transmissive qualities aren't exactly linear relative to ink density. I can't offer a lot of detail on that though.


Begin geek stuff*******

If you look at a color model such as RGB, it's really designed around wavelengths. You have several factors in determining the value of a coordinate value (x,y) for each channel R,G, and B. To represent measured light that way, you would take the intensity measured at a certain wavelength (typically represented by a greek letter lambda if you're looking at any literature on the topic), and scale its contribution by some function f(lambda). The sum of products of measured intensities and their scale factors over all wavelengths gives you a value for that channel. Anyway it's a matter of 3 equations like this, which do overlapping nonzero values.

Of course this can't produce every possible color. As I mentioned they do have some overlap in domain, which makes things such as absorption of light/energy lost to heat difficult to model.

End geek stuff*********
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  #45  
Old 04-12-2015, 02:53 PM
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Smile Re: is it better to start retouch with a flat imag

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Originally Posted by klev View Post
My suspicion is that it wouldn't work so well, because you're still bound by encoding. 16-bit in photoshop uses an unsigned integer encoding, which differs from what is used in ACR / Lightroom on raw images.
Iím confused. You wrote: What you see in the raw processor window is a representation of how the image will appear mapped into a gamma corrected space with a smaller volume than the source gamut.
If you render what you saw of said preview into ProPhoto RGB, whereís the smaller gamut? Iím not going to go deep into gamma, even PoyntonĎs work and text leads to head explosions
But if the underlying color space in the ACR engine is ProPhoto primaries in a 1.0 gamma and you get that out in say a TIFF, whatís the issue?
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  #46  
Old 04-12-2015, 04:01 PM
creativeretouch creativeretouch is offline
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Re: is it better to start retouch with a flat imag

May I have a suggestion? I think we are talking from two different points of view here and I would suggest to separate them.

One thing is to be able to create an image that everyone is happy with (you do not need to understand the theory too much - it is more intuitive work but it is good to know the basics) and another thing is to be able to exactly reproduce this image via various media (screen, print, projection - it requires really deep professional knowledge how everything works).

Do you agree with this separation?
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  #47  
Old 04-12-2015, 04:11 PM
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andrewrodney andrewrodney is offline
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Re: is it better to start retouch with a flat imag

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Originally Posted by creativeretouch View Post
One thing is to be able to create an image that everyone is happy with (you do not need to understand the theory too much - it is more intuitive work but it is good to know the basics) and another thing is to be able to exactly reproduce this image via various media (screen, print, projection - it requires really deep professional knowledge how everything works).
The debate if you will isnít about the above, I doubt anyone would disagree with the basic premise (create an image nearly everyone is happy with since I doubt we can please all the people, all the time). Itís how we get there. The how, using tools like Photoshop or a raw converter isnít something we learn at birth, we have to study the tools and techniques. So the how in both cases is somewhat important. Exactly reproduce is a potential rabbit hole I hope we donít have to go down.
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  #48  
Old 04-12-2015, 04:18 PM
klev klev is offline
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Re: is it better to start retouch with a flat imag

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Originally Posted by creativeretouch View Post
One thing is to be able to create an image that everyone is happy with (you do not need to understand the theory too much - it is more intuitive work but it is good to know the basics) and another thing is to be able to exactly reproduce this image via various media (screen, print, projection - it requires really deep professional knowledge how everything works).
I mentioned it to dispel some misconceptions. It's more complex than saying L*AB allows you to deal with luminance separately, but yeah I have quite a few (overlapping) reference books.

Quote:
Originally Posted by andrewrodney View Post
Iím confused. You wrote: What you see in the raw processor window is a representation of how the image will appear mapped into a gamma corrected space with a smaller volume than the source gamut.
If you render what you saw of said preview into ProPhoto RGB, whereís the smaller gamut? Iím not going to go deep into gamma, even PoyntonĎs work and text leads to head explosions
But if the underlying color space in the ACR engine is ProPhoto primaries in a 1.0 gamma and you get that out in say a TIFF, whatís the issue?


I think I see the point of contention, although I'm not positive I can offer a satisfactory explanation. I'm unfamiliar with Poynton's work. Anyway my point was that there is still a difference in encoding. Cameras have differing dynamic ranges. I mention cameras, because I'm considering the reconstructed signal range, which is dependent on more than the raw sensor data. This has to be mapped into a fixed range. Now obviously prophoto 1.0 has a fixed range, but to output to an unsigned integral encoding rather than a floating point type, you have to clamp anything that falls outside of a normalized range. I would have to test this to see how it impacts the results. Photoshop can only "properly" deal with gamma 1.0 data in 32 bit mode, but I would have to see how it works going from that profile to 32 bit mode. I doubt it's possible to write an export script to avoid the encoding and clamping issue.

I think we discussed this once a long time ago, but 16 and 32 bit modes do interpret the data differently. It's not even the number of bits. If you open a 16 bit EXR, it will be opened sign extended in 32 bit mode. These are implementation details that are not directly related to the number of bits assigned. If you store something in a floating point encoding, you have specific bits assigned to a signed exponent value, allowing for an extended range at the cost of some precision (can link a reference to all of the fl(something) math, but it's time consuming to read).
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  #49  
Old 04-12-2015, 04:21 PM
creativeretouch creativeretouch is offline
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Re: is it better to start retouch with a flat imag

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Originally Posted by andrewrodney View Post
The debate if you will isnít about the above, I doubt anyone would disagree with the basic premise (create an image nearly everyone is happy with since I doubt we can please all the people, all the time). Itís how we get there. The how, using tools like Photoshop or a raw converter isnít something we learn at birth, we have to study the tools and techniques. So the how in both cases is somewhat important. Exactly reproduce is a potential rabbit hole I hope we donít have to go down.
Yes, it looks very simple "to create an image everyone is happy with" but finally you will find out how difficult it is... maybe more difficult than reproduce it =)

Some people say that Billie Holiday wasn't perfect (technically) singer but I did not hear anyone to say he does not like her songs. She was only one and no one is able to sing like her.
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  #50  
Old 04-12-2015, 04:27 PM
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andrewrodney andrewrodney is offline
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Re: is it better to start retouch with a flat imag

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Originally Posted by klev View Post
I'm unfamiliar with Poynton's work.
Google that name and Gamma. Heís the Gamma man.
Quote:
Anyway my point was that there is still a difference in encoding. Cameras have differing dynamic ranges. I mention cameras, because I'm considering the reconstructed signal range, which is dependent on more than the raw sensor data. This has to be mapped into a fixed range.
Agreed but by the time weíre processing the raw, viewing the preview, thatís our new reality.
Quote:
Photoshop can only "properly" deal with gamma 1.0 data in 32 bit mode, but I would have to see how it works going from that profile to 32 bit mode. I doubt it's possible to write an export script to avoid the encoding and clamping issue.
I donít see how that is true. One can build a 1.0 Gamma (TRC) Working Space quite easily and use it on 8-bit per color or 16-bit pre color images. Now after that, whatís really happening under the hood isnít something I'm familiar with.

So, if we have a 1.0 TRC color space with ProPhoto primaries, and thatís what Iím told by people like Thomas is used in the ACR engine, and I can render in a color space with same TRC and primaries, Iím confused by this:What you see in the raw processor window is a representation of how the image will appear mapped into a gamma corrected space with a smaller volume than the source gamut.
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