toe and shoulder applied to digital

Discussion in 'Digital Photography' started by Dale, Feb 26, 2014.

  1. Dale

    Dale Guest

    sensitized photographic film and paper have a toe and shoulder in their
    contrast, it is an artifact of chemical activity and exhaustion that
    just so happens to provide a system to deal with dynamic range, such as
    highlights and shadows when such chemistry is optimized, and perhaps
    even before optimized which I don't know

    the contrast of chemical media, is modeled with rational quadratic and
    other non-linear but not cubic terms, leaving it to remain within
    measurement and hybrid systems modeling/engineering ease and simplicity

    pure digital has gamma, a linear contrast

    gamma works just fine when the capture, manipulation and output can
    handle the dynamic range of a scene or artistically created image in a
    wide enough gamut working space

    what I glean from the ICC website http"// is that output
    profiles are mapped to the maximal machine code for that device, this
    means additive systems will have the brightest display, and subtractive
    systems will have the darkest display, regardless of accuracy, perhaps
    leaving a linear toe and shoulder from the accurate gamut to the machine

    this is really not a capture issue, but it is an output and manipulation

    if you used a rational quadratic like Kodak uses for its film and paper
    contrasts from the region of accurate to machine maximal color, you
    might deal with highlights and shadows better, it involves a
    non-linearity in calculation but still a one dimensional look-up table,
    probably not as applicable to embedded systems which I don't know

    in the case of ROMM, RIMM, ERIMM, I can see why you might not want to do
    this to maintain linearity to CIE standards and the end points are not
    mapped like output devices as far as I know, except with the
    linearization to ProPhoto RGB which I will address in another post
    search for ROMM, RIMM, ERIMM and ProPhoto RGB

    my means are much limited compared to when I worked in Kodak R&D 17
    years ago, I can study stuff, but my applications are consumer capture
    and display pretty much, color manipulation is maturing in GIMP which I
    no longer have since Redhat uses a version predated color management,
    and my cell phone is not a smart phone

    I see clipping of shadows in consumer capture when printed, how printed
    I don't know
    I see clipping of highlights on at least television display (I have
    CRT),, haven't really viewed my LCD computer monitor enough to say there

    sRGB has failed the consumer use case it wanted, at the expense of some
    long term development of open systems of color, ProPhoto RGB delivers a
    centralized system,, but in gamut is not big enough to accommodate
    digital capture, impending digital display and probably digital
    projection as I gather, maybe a filter set and associated spectral
    considerations of sensitivity or density would be a better ROMM, RIMM,
    Dale, Feb 26, 2014
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  2. High-end digital cameras do not use a simple formula for mapping the CCD
    dump into RGB. Each pixel produces around 2^14 levels at ISO 100. When
    using a very clear lens, a large amount of data beyond the normal black
    point and white point is captured. The tonal curves can be adjusted and
    viewed in real-time when post-processing RAW files.
    Kevin McMurtrie, Feb 26, 2014
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  3. Dale

    Dale Guest

    I was a systems engineer who was allowed to dabble in science every once
    in awhile, so yes, I know the buzz words, and had the practical
    application of systems experience to know a little about applying them,
    since I only worked 9 years I didn't really become an expert systems
    engineer, but I think an expert knows what I am getting at

    my experience at Kodak systems R&D was

    Imagining Science Training Program
    1) first rotation, consumer paper test engineer, 1 year
    2) second rotation, consumer C-41 process engineer, I did the beginnings
    of Flexicolor Stabilizer LF, 1 year
    25% of time in classes and a nice little library of books

    3) first permanent job, Pro C-41 Process, had some interesting stuff
    like process variability of new professional films, and a little work on
    C-41 Q-Lab idea, 2 years

    4) second permanent job, Professional Hybrid Systems Integration
    (I'd like to think I was a little integral in color management), 5 years

    would have been an interesting job but I was young and caught up in the
    rat race, in retrospect I could have enjoyed life a lot more then, or at
    least been financially better off

    I was a part time Real Estate agent for awhile, I had a two family home
    and an apartment I rented

    I almost took a job as a systems engineer on Kodak's Premier PC, a
    competition to Photoshop, but the funding was not there, and there was
    overall workflow solution additionally needed

    found my teenage loves on the streets and crashed and burned, maybe if
    Rochester wasn't "smug town" thing could have been different

    pecking orders other than performance, if you want to make a new Kodak
    stop this
    Dale, Feb 26, 2014
  4. Dale

    Dale Guest

    never really got the chance to have an expert eye to do such things
    well, I like a curve I can import
    Dale, Feb 26, 2014
  5. Dale

    PeterN Guest

    He's one of the few in my killfile.
    PeterN, Feb 26, 2014
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