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Thread: RAW/NEF versus TIFF - via Camera Raw

  1. #61

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    Re: SUPPLEMENTARY OP II - Lossy vs Lossless vs 12-bit vs 14-bit

    Since Paul is the first one to say that color space is irrelevent for this discussion I will be the second one.

    Manfred,
    My eyes can't see digital values. My eyes are analogue instruments. When I look at the monitor or print they register analogue values. An image on the pc is digital. There's a D/A conversion somewhere. What's described in color management is the adjusting of my input for the output. I never understood the phrase "a raw image doesn't have a color space". It has, the color space of the R,G and B filters of the sensor. Sorry Ted, I stick with the Bayern array. The results of that process has to be adjusted for the output, your screen to gain a realistic picture on that screen. May I quote from Ted's link http://www.tftcentral.co.uk/articles..._Toc379132054:
    Introduction
    Something that has interested me for a couple of years already is the ability of displays to represent colors as they are in the real World. Very often this will depend mostly on the size of the color gamut of the display, but it is also very dependent on the color space the content was captured in and the color space it was exported in. Therefore, to get a good idea of the ability of the display to represent colors true to life, it is important to know to what amount the color gamut of the display covers certain color spaces.
    Another phrase I'm not happy with is that more bit depth means more information. The information is that light hitting the sensor and resulting in an analogue signal. Dividing that signal in the A/D conversion in 2^12 or 2^14 peaces doesn't add information. A normal output device can't handle more than 2^7 bits. In general.
    The value of 12 or 14 bits is only when editing. Avoiding banding or posterization as much as possible. And than the difference between 12 and 14 bit, well I think only eventually visible on billboards.

    And then the issue lossy or lossless compressed. I personal think it's impossible to compress raw data lossless. It's written, but I don't believe it.

    George

  2. #62
    Administrator Manfred M's Avatar
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    Re: SUPPLEMENTARY OP II - Lossy vs Lossless vs 12-bit vs 14-bit

    Quote Originally Posted by george013 View Post
    Since Paul is the first one to say that color space is irrelevent for this discussion I will be the second one.
    That is the problem with threads that have fragmented. My response was to Pica's question in #47 where he asks if the author of the article that he refers to in that posting has missed something, and in my view he has. That is why I brought up the colour space issue.


    Quote Originally Posted by george013 View Post
    My eyes can't see digital values. My eyes are analogue instruments. When I look at the monitor or print they register analogue values. An image on the pc is digital. There's a D/A conversion somewhere. What's described in color management is the adjusting of my input for the output.
    If you include what you see as part of the the output, then there is definitely an analogue component there. In terms of the technology, there is no analogue component after the A/D convertor in the camera, so long as you are using a modern display that accepts digital input. That covers virtually any display that has come out in the past decade. Many graphics cards and computer screens have analogue ports (VGA) for backwards compatibility, so if you use these, your digital display can process and display this type of data.

    Quote Originally Posted by george013 View Post
    I never understood the phrase "a raw image doesn't have a color space". It has, the color space of the R,G and B filters of the sensor.
    No R,G and B filters are not a colour space. Colour spaces are mathematical models that tell computers, including the ones in our cameras, how to interpret the colour data. Depending on which colour space is used, for example, a value of (42, 121, 189) will have a different "tone" when displayed using sRGB, AdobeRGB or ProPhoto colour space. Any image we see has to have a colour space. The camera just collects data.

    Quote Originally Posted by george013 View Post
    Another phrase I'm not happy with is that more bit depth means more information. The information is that light hitting the sensor and resulting in an analogue signal. Dividing that signal in the A/D conversion in 2^12 or 2^14 peaces doesn't add information. A normal output device can't handle more than 2^7 bits. In general.
    The value of 12 or 14 bits is only when editing. Avoiding banding or posterization as much as possible. And than the difference between 12 and 14 bit, well I think only eventually visible on billboards.
    My computer display claims to support 2^10 bits per channel. Even the low end sRGB displays claim to support 2^8 bits per channel. How well they do this, I don't know. All I know is that my eyes cannot resolve down to that level.

    Quote Originally Posted by george013 View Post
    And then the issue lossy or lossless compressed. I personal think it's impossible to compress raw data lossless. It's written, but I don't believe it.
    When I first got my D800 I tested it and saved files using uncompressed and lossless compression. The files in lossless compression were smaller than the uncompressed ones. When I manipulated these files identically in Photoshop and compared the output (using the Difference" blending mode, I got pure black output, which suggests to me that the two gave me identical results.

    I repeated this with lossy compression and here I started seeing differences, which tells me that there was some change in the data.

    Compression works by encoding patterns, so if I get the same value of pixels of a particular shade, lossless compression should be able to encode that with no loss in data. If I start throwing out some of the colour values, but maintaining all of the luminosity data (which is the primary way that lossy compression works), I have lossy compression and comparing a 4:4:4 encoded value to a 4:2:2 , I should be able to detect this by comparing a lossy versus lossless compressed image.

  3. #63
    Administrator Manfred M's Avatar
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    Re: SUPPLEMENTARY OP II - Lossy vs Lossless vs 12-bit vs 14-bit

    Quote Originally Posted by xpatUSA View Post
    I think that we have drifted well off-topic and ended up with too many rhetorical questions that can be addressed quite easily by ordinary research. One from me: what about fluorescent colors?

    Here's one answer about the 1931 2-degree Observers.



    Those numbers of subjects would make modern pollsters turn in their graves (population, sample size, confidence level, margin of error, etc).

    As you said, in the 1920's, they were probably well-nourished healthy males - rich enough to spend their time thus instead of scratchin' a living . . .

    https://medium.com/hipster-color-sci...y-401f1830b65a
    That is exactly the point I was trying to make Ted. I know of a number of other "standards" (not related to photography) that have built upon similarly "flawed" data.

  4. #64
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    Re: SUPPLEMENTARY OP II - Lossy vs Lossless vs 12-bit vs 14-bit

    Quote Originally Posted by Manfred M View Post
    That is exactly the point I was trying to make Ted. I know of a number of other "standards" (not related to photography) that have built upon similarly "flawed" data.
    Then perhaps we could agree that many such are "de facto" standards that have "achieved a dominant position by public acceptance"?

    Photography itself abounds with "de facto" standards, does it not?
    Last edited by xpatUSA; 1st September 2017 at 01:16 AM.

  5. #65
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    FYI on SUPPLEMENTARY OP II - Lossy vs Lossless vs 12-bit vs 14-bit

    Hello CiC Participants of This Thread,
    This is to convey a thank you for the contributions in order to support my "Raw and camera operations quest", as well as create a conclusion on the below follow-up items. Appreciate it.

    FYI, I have now read and will contemplate on what has been written and return if needed.

    - What I will ask this moment is, is it possible to make a conclusion, rule-of-thumb on the second item (B), like the for me valuable answer among others, on item (A):

    Quote Originally Posted by pnodrog View Post
    In general I agree with the article.

    ... important factors that I think need stressing. ... the subject and dynamic range of the scene being photographed. The test done in the article were of a scene with a fairly limited dynamic range. Had a very high-dynamic range scene (such as a sunset being reflected in city buildings) I am sure the advantages of 14bit over 12 bit would become more apparent. Such a scene would also have hard edges which would also make any loss of definition in the compressed files more obvious. Unless the photograph being taken is pushing the limits of the sensor the choice of RAW file is probably not overly important.
    Thank you ALL for this team effort!


    APPENDIX:
    Quote Originally Posted by Pica View Post
    FOLLOW UP QUESTIONS

    (A) When I first started out with the Nikon 5600, and I was going to decide if I would utilize 14-bit or 12-bit, I did a deep research and read among other things the following article; where the author have made tests (as you will see from it) comparing the results from 12-bit lossy, 12-bit lossless, 14-bit lossy and 14-bit lossless capturing.

    Your inputs above have been useful to me (actually changed how I will operate the D5600) and thus I would like to share the following article for serious scrutiny.

    WHAT DO YOU think, does the author have a point with his article and testing, or does he miss something?

    https://digital-photography-school.c...right-for-you/


    (B) As a photographer, systems engineer and human being, I cannot resist to lay the following final items on the table .

    Since we are so many competent people here in one place: We have learned about the pros and cons regarding 14-bit lossless compressed versus 12-bit lossy compressed when it comes to editing, post processing and perhaps IQ!

    However, when talking about small and large file sizes, possibilities during editing, etc: Can we here conclude (with a rationale please) what compression technique comes on second place and what comes on third? Is 12-bit lossless compression better than 14-bit lossy, or is the other way around?!

    Note that this is not an academic question – since we have learned here that some cameras (like the Nikon D5600) shoot 14-bit lossy and some (Canon xxx) shoot 12-bit lossless without any other alternatives! Without stating more during this part of the OP, I (as a systems engineer) can appreciate that this may not be settled exactly due to reasons of e.g. different implementations, compression algorithms. However I believe if the rest is created equal (Occam's razor), and based upon how the compression algorithms work on e.g. shadows and highlight, that at least a “Rule of thumb” can be established by us here!

    SO CONDENSED, do we believe that 12 bit lossless compression is the second best alternative or is it 14-bit compression lossy which takes that place.

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