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Author Topic: Film Gamut  (Read 5444 times)

alifatemi

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Film Gamut
« on: June 30, 2014, 03:03:51 am »

Does anybody know what is the Gamut of 35mm film? Adobe RGB? Pro photo?
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Bart_van_der_Wolf

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Re: Film Gamut
« Reply #1 on: June 30, 2014, 04:53:21 am »

Does anybody know what is the Gamut of 35mm film? Adobe RGB? Pro photo?

Hi Ali,

It's something in between, and depends a bit on the specific film (dye set) you are looking at.

Bruce Lindbloom has defined an optimal colorspace, BetaRGB, that encompasses all, with maximum efficiency.

Cheers,
Bart
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digitaldog

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Re: Film Gamut
« Reply #2 on: June 30, 2014, 09:38:08 am »

Depends on the film but the overall shape is quite different than either which are based on simple display-like qualities. There are colors in ProPhoto RGB that fall outside film gamut for sure, and probably a few in Adobe RGB (1998) to some degree.
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Alan Klein

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Re: Film Gamut
« Reply #3 on: June 30, 2014, 10:41:24 am »

After scanning, wouldn't you want to edit using the monitor's Native gamut?  And then changing to sRGB, etc. for the final use?

Jim Kasson

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Re: Film Gamut
« Reply #4 on: June 30, 2014, 11:18:20 am »

Does anybody know what is the Gamut of 35mm film? Adobe RGB? Pro photo?

I'm assuming that you are referring to the gamut of the captured image, not the range of colors to which the film responds. I'm also assuming that you're referring to color transparency film, since color negative film is not intended to directly produce colors, but spectra which are turned into viewable colors by another photographic medium, and the gamut of B&W film is boring, devolving down to Dmin and Dmax.

There are many kinds of transparency films, and all have somewhat different gamuts. What they have in common is that they produce colors with a subtractive model, passing light through layers of cyan, magenta, and yellow dyes. Thus, it is difficult for transparencies to produce some light, saturated colors.

You refereed to two RGB color spaces, one of with is physically realizable (Adobe RGB) and one which is simply a mathematical construction (ProPhoto RGB). RGB color spaces have an entirely different mixing model from transparency films; they add red, green, and blue light. Thus it is difficult for monitors to produce some saturated dark colors.

Since the mixing models are different, and the colorants are different, the shape of the gamut of transparency films won't match that of monitors, and thus it would be inaccurate to say that any transparency film's gamut is close to that of any RGB monitor.

If  we're looking for a digital medium to compare transparency film to, I suggest printer media. Same mixing model -- with dye printers, anyway. Similar colorants -- with four-color printers, anyway, although having black does make things a little different. And, if the printers are printing on transparent media, similar viewing.

Jim

digitaldog

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Re: Film Gamut
« Reply #5 on: June 30, 2014, 12:57:58 pm »

After scanning, wouldn't you want to edit using the monitor's Native gamut?  And then changing to sRGB, etc. for the final use?
You'd want a good scanner profile which itself should define the gamut of the capture and archive in that space as the master. From there you'd convert to any color space necessary to do whatever you wished. The fewer conversions the better, stick with scanner RGB understanding it's not necessarily well behaved like RGB working spaces (R=G=B is neutral).

We never edit in our display color space.
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Jim Kasson

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Re: Film Gamut
« Reply #6 on: June 30, 2014, 01:53:03 pm »

If  we're looking for a digital medium to compare transparency film to, I suggest printer media. Same mixing model -- with dye printers, anyway. Similar colorants -- with four-color printers, anyway, although having black does make things a little different. And, if the printers are printing on transparent media, similar viewing.

As a complete aside, I've always thought that, if the Kodak/Fuji/Agfa chemists could have worked it out, it would have been really nice to have a 4th, black layer in transparencies. We might have less color shift as the luminance varied.

Jim

alifatemi

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Re: Film Gamut
« Reply #7 on: July 01, 2014, 02:22:31 am »

Thanks for your info everybody, I was just curious where the transparency/negative film gamut stands compare to digital. of cource if we scan a film, then everything will be limited in digital working space cage.
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Jim Kasson

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Re: Film Gamut
« Reply #8 on: July 01, 2014, 10:54:53 am »

Thanks for your info everybody, I was just curious where the transparency/negative film gamut stands compare to digital.

When you bring negative film into the picture, it sounds like you're probably talking about the range of colors in the original scene that can be captured, not what I and everyone else who responded thought you meant.

Which are you curious about, the gamut of colors that can be captured, or the gamut of colors that you can see when looking at the developed film? (which I'll call output gamut)?

By the way, the topic of capture gamut is nowhere near as straightforward as the topic of output gamut.

Jim
« Last Edit: July 01, 2014, 11:02:12 am by Jim Kasson »
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alifatemi

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Re: Film Gamut
« Reply #9 on: July 01, 2014, 11:09:21 am »

developed film, output gamut but now I know what I was looking for.
« Last Edit: July 01, 2014, 11:11:15 am by alifatemi »
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digitaldog

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Re: Film Gamut
« Reply #10 on: July 01, 2014, 11:58:42 am »

This might help, a simple 2D gamut map of an Imacon 848 vs. Adobe RGB (1998). I don't recall the film used for creating that profile back in 2002.

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