E-6 to C-41: A Transition

[Drew Wiley]

Latitude is not gamut. Two different variables, at least until the point the chrome
bottoms of tops out, which is beyone its intended usage anyway. Gamut more specifically applies to what specific hues will reproduce within that hypothetical sphere. When primaries intersect, a neutral is formed which disallows distinction of
similar hues. We have a problem here with basic vocabulary and color theory. Mine
is based upon standards which cut across many industries, and which have been in
place almost a hundred years. Neutrals aren't necessarily bad, but when they are
predominant, as in portrait films, something has to give in terms of saturation and
clarity of the other hues. The nature of the difficulty hasn't changed since color neg
films were first introduced, though progress has been significant. But if you want really clean reproduction, neither color negs or chromes are the way to go - just
build a sharp-cutting tricolor camera using black and white film (not exactly a point
n' shoot option, however).

[Drew Wiley]

Should have added, that's why modern computerized color mapping requires a four
dimensional model, with a separate axis being used for tone than for tint (white vs
black content). It's easier to write that way. And in this respect, white is not just
brightness; it's an ingredient and essentially contamination of each layer, like you
get in subtractive color systems (not additive, though I accidentally reversed the
terms earlier). But about all you have to do is go to Kodak's marketing images to
see how they've gotten pros to highlight the flavor of specific films, with the new
Portra leaning heavily toward portraiture. Films all still have a signature.

[Ben Syverson]

Latitude is not gamut. Two different variables, at least until the point the chrome
bottoms of tops out, which is beyone its intended usage anyway. Gamut more specifically applies to what specific hues will reproduce within that hypothetical sphere.

Wrong. Re-read this.

"Gamut" encompasses brightness—and "latitude" is another way of saying "range of brightness."

Latitude is in fact a key component in gamut. Imagine you could only represent colors at one stop—Sunny 16, EV 15. If EV was 16, the output would be pure white. If EV was 14, it would be pure black. But this hypothetical sensor could reproduce any color under the sun, as long as it was EV 15.

The gamut chart for such a sensor would look like a deflated beach ball floating in 3D space next to even sRGB.

[Drew Wiley]

Ben - I haven't willed anything into truth. This is old,old, very routine stuff to color
specialists. Basic theory, and it amazes me that a little bit of gadgetry can make one
think it's obsolete. I've sat down and had respectful conversations with the head of
the International Color Council and discussed pros and cons of spectrophotometer
design, and we understood each other. I can talk to X-Rite engineers and we perfecty understand one another. Why is this conversation so difficult?

[Ben Syverson]

I can talk to X-Rite engineers and we perfecty understand one another. Why is this conversation so difficult?

I don't know—you tell me. I've given you a mountain of information about why you're mistaken, and you've basically told me to make some wet prints and judge them by eye.

If you insist that transparency films can do amazing feats of image capture that negatives can't touch, I'd say the burden of proof is in your court, my friend.

[Drew Wiley]

Ben - I've got to do something more exciting right now like work on taxes. I apparently just don't have the skills to teach Kindergarten color theory to kids more
interested in eating their paint.

[Ben Syverson]

Drew, I have no doubt that you know more about color theory than I do. I know this because you write it so often, and with such passionate conviction.

In fact, you seem to be so scholarly that you don't even feel moved to demonstrate or exercise your knowledge. I can only hope to reach that level of enlightenment.

I suppose at your level, one transcends worldly trappings such as "data," and simply divines Color Truths from the Gods.

But thanks anyway for the ad hominem.

[rdenney]

Sheesh.

I'm a systems engineer, in addition to other things. I don't measure things against an absolute standard, because nobody in the engineering world can define let alone afford absolutes. I think in terms of fulfilling requirements, and requirements emerge from goals and needs, not the other way around.

Drew's empirical evidence is in the coloration of a few specific minerals in the work that he does. He is also making very specific color separation exposures for making dye-transfer prints. The requirements that emerge from those activities, particularly in the context of the intended processes, are considerably different from those that emerge from the activity implied in the original post.

It has been said and said again that it wasn't the OP's intention to fulfill Drew's exacting requirements, but rather the much more general requirement of achieving the "look" of E6 when using C41 materials.

Much of the argument is based on words like "quality" and "look". But those words have no testable definition, and can't be used as requirements in the practical world (and, Drew, it was you who mentioned the practical world).

The biggest mistake people make is imposing their requirements on everyone without checking to be sure they trace to the activities of others. I write policy for systems engineering compliance, and have to devise ways to lead people through systems engineering processes without tell them what their needs and activities are, so I know how tempting this mistake can be. Many engineering projects--and color matching is an engineering project even if the standards applied to it are based in artistic objectives--run off the rails because the requirements are not nailed down based on what their owners actually do.

Ben's standard is "reasonable", and Drew's is "exacting", and each is an appropriate requirement given what each do and hope to achieve. To say one necessarily applies to the other makes the mistake I warn against.

For constructing a model of what everyone should do, it's easy: If you will do what Drew does and apply Drew's standards, then you have much work ahead of you to determine which process fulfills your requirements. If you just want to achieve a general look of transparency film using negative materials, then Ben has outlined an approach that will fulfill those requirements.

The next step in these arguments is for one person to say that the other person's requirements are wrong, and then when they are traced accurately to what they do and their needs, then the attack shifts to them having the wrong goals. I have presided over many, many meetings where the conversation had gone that way and it was up to us to bring it back. Thinking another person's goals are invalid because they are not our goals is where the insult is.

Rick "it ain't about the logarithms" Denney

[Ben Syverson]

Rick, I think part of the problem is that there are actually two arguments in this thread: one is that E6 and C41 films are impossible to match, and the other is that E6 films can capture colors that C41s simply can't.

Obviously I take exception to both, but I would not impose my standards on anyone else. I think you should test for yourself. My problem is precisely that Drew repeatedly tells people "you can't do that" on this thread, without backing it up.

[Drew Wiley]

No ... my problem was with trying to communicate with sheer visual illiteracy. The data
was right in front of your very nose but you don't understand how to interpret it sensibly. I gave a subtle hint. Just go back and study some of the old color guide books and they will gently introduce you to the subject. The Kodak guides weren't written for engineers. But the response was, this is 1970's stuff and obsolete. No. The graphs by Fuji and Kodak are still made the same way and are still just as relevant if applied to current products. You don't have to analyze things that in partiuclar manner, but this is a shortcut which simplifies actual film testing. Imagine going into an elementary astronomy class and stating that you don't have to learn the significance of Copernicus or Galileo because their idea are hundreds of years old and therefore now meaningles. Guess what, the earth still revolves around the sun.