Film curves...

Vesa_Ekholm

• 2009年01月06日 15:41

Well, now that I´m on to ask a lot of questions, here´s the next one 😄

Filmcurves...what do they actually do ? I mean...obviously, I can see how they affect the image, but do they do somethin that can´t be achieved with curves, contrast slider etc.

Forexample the linear curve, which has proved to be very usefull applied to images with snow and ice... As i see it...it gives balance between bright and dark areas. But how does it do it ?

Just curious and so that I would understand it better ❗️ ❓

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  Paul Steunebrink

  • 2009年01月07日 11:16

  Nice question, and since you are not flooded with answers, I give you my (non-scientific) take on the topic.
  
  Back in the old days, when I was developing and printing my black & white film, I controlled film contrast with film processing as well as with different types of paper and different developers. A film developed to a high contrast and compensated with low contrast paper did not render the same result as the other way around. Lesson: what is not there in the film anymore is not going to show in the print, ever, or at a cost (loss of tonality, lot of trial-and-error of manual corrections).
  
  The ICC profile and film curve are 'Base Characteristics' in CO4 lingua and very right so. You could compare them with how a film is developed, that is how light values are translated into densities (either B&W or color). To put it into a more daring statement: In the digital domain these base characteristics translate raw values (which are luminance only and arranged linear) into non-linear RGB values we are more familiar with. Other corrections like levels and curves are affecting these RGB (assumption, not sure) values based on the film curve.
  (I left the demosaicing process out of the equation for simplicity here)
  
  In day-to-day practice, changing the film curve heavily effects the histogram and therefore all other exposure, dynamic range, levels and curves settings like the ICC profile affect color. Therefore you set this first. What is gained (or lost) with the film curve setting can only be adjusted or compensated for to a lesser extend with other tools or by using major adjustments affecting the entire image in a (probably) undesired fashion (see my comparison with film printing).
  
  These type of settings is what makes Capture One one of the most photographic tools in its kind, IMO. It gives you extensive control at all (relevant) levels of the process. Maybe not for the faint of heart, it challenges the photographer to go to the limit of its possibilities and imagination. (wow) 😉

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  Vesa_Ekholm

  • 2009年01月07日 15:24

  Thanks Paul...

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  Christopher

  • 2009年01月07日 20:14

  Paul is right on (as usual 😊 ), but I'll add a tiny bit more. Indeed, the film curves are applied before any other adjustments. Think of them as how the negative is being developed, and the other adjustments as how that negative is being printed.
  
  Also as Paul says these film curves are rather large changes. While it may be possible using the final processing curves setting to make a linear film curve appear nearly similar to one of the others; it would be impossible to restore linearity no matter what tweaking you try to apply.
  
  On a personal use note: I like the high contrast for when I'm shooting with my 50mm f/1.4 wide open because it is a low contrast lens. While it is less film-like, linear, as you found, sometimes a better starting point for images with wildly varying exposure zones because it does apply less initial processing.

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