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Thread: Anyone using Darktable and know about parametric and drawn masks?

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    Account Closed tduell's Avatar
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    Anyone using Darktable and know about parametric and drawn masks?

    Hello All,
    I'm stuggling to come to grips with how one can use these masks.
    I have a particular problem that would, on the surface, appear to be an ideal candidate...child shot in bright sun, with quite sharp shadows on the face.
    Having read what I can find and watched on-line video tutorials, my understanding is that I should be able to define a parametric or drawn mask (say a circle or similar) located on the child's face and then use the 'shadows and highlights' module to make adjustments only within the mask region.
    Blowed if I can get any sensible results.
    I guess the best answer is don't take shots like that

    If you know how this business is supposed to work, or know of a particularly good tutorial on this, please let me know.

    Cheers,
    Terry

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    Arch-Σigmoid Ausphotography Regular ameerat42's Avatar
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    Hmm! Ph.D (Doctor of Photography) stuff, TD. I will go and have a look.

    - - - Updated - - -

    And so, having got a 1/4 of the way through this, I would hazard to assert
    that it is fairly informative.
    CC, Image editing OK.

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    Quote Originally Posted by ameerat42 View Post
    Hmm! Ph.D (Doctor of Photography) stuff, TD. I will go and have a look.

    - - - Updated - - -

    And so, having got a 1/4 of the way through this, I would hazard to assert
    that it is fairly informative.
    Hello Am, I had been through that tute, but found it a bit inscrutable even at full screen, as the module details where almost unreadable.
    I thought I had got enough of the gist of it, but clearly haven't.
    I'll have to have another look at it, or maybe a few looks, and then see if I can apply it.
    I think this is probably a 'work in progress'
    Thanks for your help

    Cheers,
    Terry
    Last edited by tduell; 28-01-2016 at 7:40pm.

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    Arch-Σigmoid Ausphotography Regular ameerat42's Avatar
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    No worries. It was minor, and I learned a [indeterminate item] or two.
    From the "abstrusity factor" I assigned to the whole thing, I'd agree about it being
    a "work in progress". Interesting though.

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    I like my computer more than my camera farmmax's Avatar
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    I have no experience with Darktable, only Raw Therapee. I've looked at the tutorial and it all makes sense to me (might be different if I put it into practise!). I understand what he is doing, because photoshop can make selections in a large variety of ways, and permits intersection of selection areas as well, although most people don't use these. It was very interesting to watch.

    You most definitely should be able to select areas of bright (or dark) by a parametric mask. He used Hue in his example, but you would look at using Luminosity ( darkness or lightness) This is what we call a luminosity mask in Photoshop. When you create the parametric mask using luminosity, you will be selecting ALL the light ( or dark) patches in your image, where as you only want to select the shadows on the child's face. I guess you then need to add a drawn mask to refine the selection to the dark areas on the childs face by intersecting the drawn and parametric masks.

    I notice near the end of the video he mentions and points to a brush tool for masking. It might be worth looking for a tutorial on using the brush tool, where hopefully you can just paint to choose the areas you want to apply the shadow/highlight settings to. That is the way most editing programs would do it.

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    Quote Originally Posted by ameerat42 View Post
    No worries. It was minor, and I learned a [indeterminate item] or two.
    From the "abstrusity factor" I assigned to the whole thing, I'd agree about it being
    a "work in progress". Interesting though.
    I have pondered on this tute some more, and it is all finally beginning to sink in...I think they call it "the dawning" .
    I think technique is all quite cunning, and probably well designed, just a few conceptual "hills" one has to get over.
    It is probably still a bit of a "work in progress" for me.

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    Ausphotography Veteran tandeejay's Avatar
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    I wonder if the problem of it not working for you could purely be a case of too much contrast between the sun lit part of the image and the shaded part.

    Even with RAW images it is possible for the contrast ratio to be so great that there is not enough info in the shadow/highlight to be able to recover. Only option then would be exposure bracketing and HDR, or use a fill flash so the shadow isn't so harsh.
    John Blackburn

    "Life is like a camera! Focus on what is important, capture the good times, develop from the negatives, and if things don't work out take another shot."


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    Ausphotography irregular Mark L's Avatar
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    As usual I can't help, but do have a question.
    Is there a particular reason you use Darktable? Would GIMP offer what you are after?

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    Quote Originally Posted by Mark L View Post
    As usual I can't help, but do have a question.
    Is there a particular reason you use Darktable? Would GIMP offer what you are after?
    Hello Mark,
    I use Darktable because it is a 'proper' RAW converter/developer, and I'm not partial to doing bits in one package then bits in another, although that would probably depend on just how desperate I was. GIMP is currently restricted to 8 bits/channel, so not my first choice for PP, whereas Darktable will export in 16 bit TIFF. It even has an ability to export in 32 bit TIFF but can't imagine how that could be useful at the moment.
    I did export from Darktable (jpeg) the other day to try 'Wavelet Sharpening' in GIMP, but that was a one-off experiment.
    I find it hard enough to be proficient with one package of this ilk let alone two, and GIMP isn't exactly high on the list of 'easy to use'.

    Cheers,
    Terry

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