Luminous Landscape Forum
Raw & Post Processing, Printing => Digital Image Processing => Topic started by: ErikKaffehr on August 23, 2011, 03:29:41 am
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Hi,
I see two interesting things on my "Stouffer wedge" shot comparing LR and "dcraw"
1) LR can separate significantly more steps
2) Darks in LR seems to be nonlinear
My setup is probably not optimal but the plots are made from the same DNG image.
Any comments?
Best regards
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Hi Erik,
Your screenshot shows Brightness +50, Contrast +25 which means you're applying a non-linear tone curve. Did you intend this?
Eric
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Hi Eric,
No, not what I intended. What is your suggestion?
Best regards
Erik
Hi Erik,
Your screenshot shows Brightness +50, Contrast +25 which means you're applying a non-linear tone curve. Did you intend this?
Eric
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Hi Erik,
I guess it depends on what you're trying to evaluate. For a basic scene-referred rendering (no tone curve), you can set both Brightness and Contrast to 0 (and Blacks to 0 and Point Curve to Linear, which you've already done). Once you start having the tone curve components enabled, then your evaluation is highly-dependent on the shape of those curves. Does that make sense?
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Hi!
Thanks for your suggestions. I assumed that brightness and contrast slider had default values that would be linear. I'm very much aware of photorealistic and pleasnat are different things.
NTW, what is your recommendation for repro? Is there any preset?
Best regards
Erik
Hi Erik,
I guess it depends on what you're trying to evaluate. For a basic scene-referred rendering (no tone curve), you can set both Brightness and Contrast to 0 (and Blacks to 0 and Point Curve to Linear, which you've already done). Once you start having the tone curve components enabled, then your evaluation is highly-dependent on the shape of those curves. Does that make sense?
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Hi Erik,
Sorry I don't quite understand your question. Can you please clarify?
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Hi Eric,
I presume hat in repro we want to reåroduce the colors as exactly as possible. Not having pleasant color but exact colors. So my question is what settings would be used best possible reproduction of colors. I don't mean scene rendering but reproduction of artwork.
Repro is something I don't ver often, so I have now knowledge in this area, that's the reason I'm asking.
Best regards
Erik
Hi Erik,
Sorry I don't quite understand your question. Can you please clarify?
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Hi Erik,
Now I understand. For that application you essentially want a scene-referred rendering, which can be (mostly) accomplished with
Brightness 0
Contrast 0
Blacks 0
Point Curve = Linear
You would also probably need to build a different color profile. (The "Adobe Standard" ones, for example, have color mappings intended for general photography rather than scene-referred reproduction.)
Ideally for repro work you would build the color profile using training data drawn from the stimuli / materials that you intend to photograph. (e.g., for artwork you would want to optimize the color matrix based on the representative pigments, oils, etc. of the art that you intend to photograph). I mention this because this is quite different from using training data for general-purpose photography (e.g., skin tones, sky, grass, etc.)