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Photochemical color timing


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#1 John Butler

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Posted 02 November 2008 - 09:04 PM

I speak with not as much as experience as I would like in this area, but I am curious about something. I have noticed that modern DI color graded films have a strange, "pulled-out" color palette most of the time, and that they have a sharply contrasting look to films even from the 1990's. For a slightly more convincing older look, would photochemical color timing create a more "classic" color palette than the popular method used today? Or am I pretty much spouting gibberish?
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#2 Simon Wyss

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Posted 03 November 2008 - 04:41 AM

Up to this day there has not ever been photochemical timing. That would imply exposure of printing stock through a selected single frame of the negative at one of 50 steps for each printing light colour, red-green-blue. Such strips would then be processed and projected by an intensely cooled strip projector. I am on the way to offer this in black and white with the 50-step scale on 35-mm and 16-mm stock.

What you mean has to do with the latest generations of colour film stock and the chemistry. In conjunction with Digital Intermediates you have a different exposure of the respective stock from what happens when you go camera neg - interpos - interneg -positive. New internegative stocks are in use for the purpose of DI which behave unlike traditional internegatives. Grading/timing assessments ever since 1957 have been simulations on CRT first and other monitors later. Before introduction of the Hazeltine Analyzer 50 years ago graders almost always judged by the naked eye. Subtractive colour correction gelatine filters were used. They still can be used. But find an experienced grader and an old printing machine ! Eastman-Kodak recently brought out a new series of Wratten gelatine filters. It could be an adventure . . .
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#3 Brian Pritchard

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Posted 03 November 2008 - 04:44 AM

I speak with not as much as experience as I would like in this area, but I am curious about something. I have noticed that modern DI color graded films have a strange, "pulled-out" color palette most of the time, and that they have a sharply contrasting look to films even from the 1990's. For a slightly more convincing older look, would photochemical color timing create a more "classic" color palette than the popular method used today? Or am I pretty much spouting gibberish?

I don't think you are 'spouting gibberish', John. The only way to get a 'film look' is to make a print from a negative. Whenever DI's are introduced there will be some changes to the image colour, structure and definition. Invariably some colour changes are introduced purely by the video setup method and it is unlikely that the colourist would not introduce some changes to the colour palette, one of the reasons for going through the DI route anyway. I am sure not everybody will agree but that is the way I see it.
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#4 wolfgang haak

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Posted 03 November 2008 - 06:46 AM

changes in technology and workflow will always influence the outcome.

So the question do films using DI have the same look as film in the 90's is inevitably yes. Film stocks have changed since the 90's as well, so the result will change here too.

Isn't this more of a question of preference though? Do you like what you see on screen? After all, only the people on set know what the "real thing" looked like. Just a thought.
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#5 K Borowski

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Posted 03 November 2008 - 07:12 AM

Well, it isn't just film stocks changing, as Wolfgang says.

What I believe is the biggest problem is the limited dynamic range of most digital scans. I don't know for certain, but it's probably only 8- or 12-bit. 14-bit tops.

Film resolves more than 16-bit color, and, in fact, this is where it has much higher resolution than digital. It isn't straight spatial resolution, per se, but rather a higher color and dynamic range resolution.

This is what you are using with a standard 2K DI. Now, if you got a 4K scan with a scanner that could capture higher dynamic and color bit depth, things would be different. . .
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#6 K Borowski

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Posted 03 November 2008 - 07:16 AM

Grading/timing assessments ever since 1957 have been simulations on CRT first and other monitors later. Before introduction of the Hazeltine Analyzer 50 years ago graders almost always judged by the naked eye. Subtractive colour correction gelatine filters were used. They still can be used. But find an experienced grader and an old printing machine !


Hey Simon, weren't they still making Cinex strips into the late '60s early '70s? That, I assume, would imply that they were still judging exposure and color by eye 35-40 years ago? Or were cinex strips because of CRT monitor that hadn't become accurate-enough to determine results yet?

I assume that CRTs weren't always accurate back then because, even today, I've had printers tell me they can't always be trusted, probably more due to laziness in calibrating them to the print stock with each new emulsion batch than the faults of the monitors themselves.
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#7 Brian Pritchard

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Posted 03 November 2008 - 08:45 AM

Hey Simon, weren't they still making Cinex strips into the late '60s early '70s? That, I assume, would imply that they were still judging exposure and color by eye 35-40 years ago? Or were cinex strips because of CRT monitor that hadn't become accurate-enough to determine results yet?

I assume that CRTs weren't always accurate back then because, even today, I've had printers tell me they can't always be trusted, probably more due to laziness in calibrating them to the print stock with each new emulsion batch than the faults of the monitors themselves.


Even today VCR's are not 100% accurate; invariably the grader will have to make sight corrections to produce an acceptable answer print.

The first lab I worked in, Filmatic, was still sight grading colour in 1971 when we purchased our first Hasletine VCR. The grader went through the negative, grading for density, a print was made and he would then colour correct by eye. Most of our graders could get an acceptable answer print on the first attempt.

We were also colour reversal grading which was all done by eye and continued to be, even after the arrival of an analyser.

Today when making graded internegatives from colour prints or reversal originals I still sight grade, using filters to verify the colour correction required, even though the Kodak Analyser at the lab has the facility for positive to positive grading.

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#8 wolfgang haak

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Posted 04 November 2008 - 06:04 AM

Karl,

I know from a friend of mine who's working for a big digital VFX house (DNeg) that they scan everything to to 32bit EXR. I've noticed that exr's aren't popular around here, but they do have their merit, especially as nearly all VFX programs can output them. The workflow happens a 4k 32bit from DI scans and stays there until the how chebang gets printed back on film for release. For the biggest productions (The Dark Night) they filmed on 70mm/35mm scanned to 8K and worked 8k 32 all the way through. As their facility manager said:
"The real challenge is how much electricity you can get into a facility to run all that storage..."
With off the shelf software 4K@32 bit remains the technical threshold for the time being where the failure (crash) rate in post stays manageable.

HellBoy II / Dark Night are heavily funded projects, but you can scan at higher bitdepth, and for the big boys it's routine. I for my day to day work render to 32 bit exr as well when producing 100% CGI work.

scary, memory eating stuff ;)
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#9 Hal Smith

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Posted 04 November 2008 - 01:13 PM

...........Today when making graded internegatives from colour prints or reversal originals I still sight grade, using filters to verify the colour correction required, even though the Kodak Analyser at the lab has the facility for positive to positive grading.

Which makes perfect sense if you think about it. If the ultimate receptor of a filmed project is going to be the human eye isn't it rather obvious that the best judge of any intermediate steps is the educated human eye?

I've never personally known a film timer but a good friend in the past was a Master Lithographer at a high end printing facility in Chicago whose main work was things like brochures for ad agencies. He could see fine gradiations in printed color quality that were at best vaguely recognizable to my eye. More importantly he knew how to adjust his 4-color German press to fix any problems in his printed product. He definitely was a master at what he did for a living.
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#10 Leo Anthony Vale

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Posted 04 November 2008 - 04:59 PM

Hey Simon, weren't they still making Cinex strips into the late '60s early '70s? That, I assume, would imply that they were still judging exposure and color by eye 35-40 years ago? Or were cinex strips because of CRT monitor that hadn't become accurate-enough to determine results yet?


When i was at WRS, the timers would time reversal originals and YCM masters by eye.

Though the guy that timed the YCMs was usually way off. I would cut the replacement I/N made from the YCMs into the original neg reels. The client would complain about a timing flash at the cut & i would compare the numbers on the timing sheets and drop my jaw at how far off they were off between the original and replacement footage. They were able to match the footage, but at the price of a noticable timing flash.
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#11 K Borowski

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Posted 05 November 2008 - 07:25 PM

Karl,

I know from a friend of mine who's working for a big digital VFX house (DNeg) that they scan everything to to 32bit EXR. I've noticed that exr's aren't popular around here, but they do have their merit, especially as nearly all VFX programs can output them. The workflow happens a 4k 32bit from DI scans and stays there until the how chebang gets printed back on film for release. For the biggest productions (The Dark Night) they filmed on 70mm/35mm scanned to 8K and worked 8k 32 all the way through. As their facility manager said:
"The real challenge is how much electricity you can get into a facility to run all that storage..."
With off the shelf software 4K@32 bit remains the technical threshold for the time being where the failure (crash) rate in post stays manageable.

HellBoy II / Dark Night are heavily funded projects, but you can scan at higher bitdepth, and for the big boys it's routine. I for my day to day work render to 32 bit exr as well when producing 100% CGI work.

scary, memory eating stuff ;)
Wolfgang


Hey Wolfgang, forgive me for mis-stating what is done. I've never done any of this myself, mind you, but I understand that at some point they drop it down to a 10-bit file for the majority of 2Ks, so while they may be *working* with 32, you throw out all but 10 at the end. Is this not the case?

I mean, ultimately you'll see a slight improvement by at least working with a higher bit-depth, but the final down-grade really makes this subtle, IMO.
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#12 David Mullen ASC

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Posted 05 November 2008 - 07:36 PM

Hey Wolfgang, forgive me for mis-stating what is done. I've never done any of this myself, mind you, but I understand that at some point they drop it down to a 10-bit file for the majority of 2Ks, so while they may be *working* with 32, you throw out all but 10 at the end. Is this not the case?

I mean, ultimately you'll see a slight improvement by at least working with a higher bit-depth, but the final down-grade really makes this subtle, IMO.


I don't think the conversion from 32-bit linear to 10-bit LOG is as simple as throwing away 22 bits. Most film scans are 10-bit LOG, whereas a lot of computer effects work is done in linear and converted later to LOG. LOG is one method of compressing dynamic range into a curve suitable for film-out work.
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#13 wolfgang haak

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Posted 06 November 2008 - 03:56 PM

I don't think the conversion from 32-bit linear to 10-bit LOG is as simple as throwing away 22 bits. Most film scans are 10-bit LOG, whereas a lot of computer effects work is done in linear and converted later to LOG. LOG is one method of compressing dynamic range into a curve suitable for film-out work.



That's right David. The digital imaging workflow is linear (a tonal correction curve aka 'gamma') is applied by the software on screen for viewing, but the files remain linear.

some idea of numbers:
Data amounts: a 10 bit file can hold up to 210 = 1024 values per channel. (binary 10 bits!)
32 bit 232 = 4294967296 values per channel.


To perform a tonal compression on this means to throw away 4294966272 values per channel. That would be to some degree insane, but it's certainly not what they are doing . the log format is somewhat more complicated. Here's a snippet from cineon.com:cineon.com


"2.1 Full Latitude
The Cineon scanner is calibrated for a 2.048 density range: this allows it to capture the fill latitude (density range) of the negative film with some margin at top and bottom. The scanner light source is balanced on film dmin so that the resulting digital image will have a neutral color balance if the film were exposed at the correct color temperature. The Digital Negative includes significant headroom above the nominal white point to handle over-exposed negative films and scenes with wide contrast range.
2.2 10 bits
With 10 bits per color over a 2.048 density range, the resulting quantization step size is 0.002 D per code value. This is below the threshold for contour visibility, which insures that no contour artifacts (also known as mach banding) will be visible in images. Furthermore, having 10 bits rather than 8 bits allows the Cineon scanner to capture the extended headroom of the negative film. "


hope this shed some light on the issue...
Wolfgang
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#14 Marc Roessler

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Posted 08 November 2008 - 03:40 PM

concerning the desaturated color palette of most current films, it seems seems to be in fashion..
Even ice cream advertisements (both in the theater and printed to paper) showing blue swimming pools seem to go for that look - and this is where I'd expect popping colors, but it's just all milky and toned down! I don't get it. It does look somewhat sleek, but it doesn't really please the eye.

Edited by Marc Roessler, 08 November 2008 - 03:41 PM.

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#15 K Borowski

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Posted 08 November 2008 - 05:26 PM

Just a quick update. It's been a long time since I've been working digitally with color, thank God, but I actually should have said 8-bit per color-channel color.

So 32-bit color is actually only 10 2/3/primary color bits.

It ought to be at least 16 PER CHANNEL to get to where film negatives can roughly do if you were to want to get all of the color information out of them.

There's a website somewhere, yeah I know a website, that seems to be the only comparison of film/digital resolutions that takes all factors into account, including dynamic range and color range.

While 2K gets more than an adequate amount of resolution linearly, the amount of color range and dynamic range that you get with film is not being adequately scanned from negatives with the current workflow. I can tell because I can see that DIs look "flat".

Desaturated is popular because it takes up less file space. . . :blink:
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#16 Glen Alexander

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Posted 08 November 2008 - 07:16 PM

Karl,

Quick question, i want to process some kodak hi-con 5363, CHEAP, quick and easy without going to a lab. do you have a quick list for the "soup"? i want to get a gamma of about 2.95 or so.

http://www.motion.ko..._Films/5363.htm

are you over in the new studios? is david lynch getting a production going?

Edited by Glen Alexander, 08 November 2008 - 07:17 PM.

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#17 K Borowski

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Posted 08 November 2008 - 07:25 PM

Karl,

Quick question, i want to process some kodak hi-con 5363, CHEAP, quick and easy without going to a lab. do you have a quick list for the "soup"? i want to get a gamma of about 2.95 or so.

http://www.motion.ko..._Films/5363.htm

are you over in the new studios? is david lynch getting a production going?


Glen, are you being serious or sarcastic?

I've never processed B&W neg. to spec. before. I did a test once using D-76 with some Plus-X or Double-X, and I've done Foma R-100 too, but never 5363 as a camera stock.

Dominic Case would be better able to answer your question. I'll forward this link to him.

If John Pytlak were here, he'd say you'd need to test first, and that this is a non-standard process not guaranteed to give optimum results. He'd also have probalby about a dozen links to the Kodak website that'd help you. So I'd recommend you search more there. Also, do an internet search for "movie film processing". George Selinsky and Martin Baumgarten have a wealth of information out there.

Finally, I'd say you'll probably want to use D-19 or D-11 or even D-8, as that sounds like an ultra-high gamma. Isn't normal like 0.8 or 1.8? You could probably get away with using Dektol, if it's available in France, but it'd be better with a silver solvent like sodium thiocyanate added. Try for D-19 or another of the scientific/X-ray developers I've listed.

As for your last sentence, I have no idea what you're talking about :ph34r:


Also, please try not to cross post. Feel free to start a new topic, send me an email, or send me an instant message, but please do not interrupt others' posts just to talk to me.
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#18 Glen Alexander

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Posted 08 November 2008 - 07:57 PM

Glen, are you being serious or sarcastic?

I've never processed B&W neg. to spec. before. I did a test once using D-76 with some Plus-X or Double-X, and I've done Foma R-100 too, but never 5363 as a camera stock.

Dominic Case would be better able to answer your question. I'll forward this link to him.

If John Pytlak were here, he'd say you'd need to test first, and that this is a non-standard process not guaranteed to give optimum results. He'd also have probalby about a dozen links to the Kodak website that'd help you. So I'd recommend you search more there. Also, do an internet search for "movie film processing". George Selinsky and Martin Baumgarten have a wealth of information out there.

Finally, I'd say you'll probably want to use D-19 or D-11 or even D-8, as that sounds like an ultra-high gamma. Isn't normal like 0.8 or 1.8? You could probably get away with using Dektol, if it's available in France, but it'd be better with a silver solvent like sodium thiocyanate added. Try for D-19 or another of the scientific/X-ray developers I've listed.

As for your last sentence, I have no idea what you're talking about :ph34r:


actually quite serious about a fast dev. yes this is extremely high gamma. the dev time needs to be kept to minimum to avoid smearing. if i use off the shelf standard dev, the timing gets too long.

you have no idea, the original poster actually might be interested as it is a similar topic about processing and chemistry.

as for last sentence

http://www.variety.c...e...980530&cs=1

your sig now says warsaw..
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#19 Dominic Case

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Posted 09 November 2008 - 11:16 PM

Karl sent me the link to this thread. Reading through I was more interested in the colour timing discussion. Not sure why it was abruptly swung over to black and white hi-con, I can't think of a subject that is less related in this general topic. "So-called "photochemical timing" is not about processing or chemistry.

So, maybe someone knows how to cross this over into a new thread, I can't figure that out at the moment. It would have been better to start a new thread on b/w hicon processing and leave this thread to the colour grading topic.

Moving on, this stock requires a high contrast positive (print) developer - D-97 is recommended. It's a hydroquinone-based developer, but canb use Ascorbic acid instead.

As D-97 is a hi-con developer you should have no trouble getting the gamma you want (around 2.95). Dev time varies, I'm not sure what the specified time is. If you want it in a short processing time, you can raise the dev temperature easily to around 24 or 25 deg ©, but beware of going much warmer, and ensure that the stop and wash are at a similar temperature. But you might be able to halve the dev time at the higher temperature.

Have a look at Kodak's processing manual.
http://www.kodak.com...h2415/h2415.pdf
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#20 Dominic Case

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Posted 09 November 2008 - 11:39 PM

Up to this day there has not ever been photochemical timing. That would imply exposure of printing stock through a selected single frame of the negative at one of 50 steps for each printing light colour, red-green-blue. Such strips would then be processed and projected by an intensely cooled strip projector.

Back on topic, I'm mystified by this response. Any chance of further explanation?

Meanwhile, I think the question was not about how accurately grading/timing could be done by eye, by trial and error, by laying filters over test prints or two-frame pilots to assess corrections, or by previewing on Kodak Analyser, Hazeltine or Colormaster.

All of these methods are capable of leading to similar results if the grader is good at her or his job.

Those results will be almost entirely dependent upon exactly how the original negative was lit and shot. Print grading (a clearer term than photochemical grading) is really based on the philosophy that the DoP knows what they are doing, and has enough experience to predetermine the results. Grading is mostly fine tuning to compensate for variable exposures, colour cast in lenses, different emulsion batches and so on - and to a small extent, to impart a mood on the film or the scene. The "look" and the colour fidelity is largely determined by the emulsion manufacturer.

So it isn't really a limited range of controls, it's a sytem that is quite adequate for the task.

Now, with DIs giving the ability to produce much more artificial colour palettes after the shoot (actually, after the emulsion is coated!), we seem to have extended our visual language. Those desaturated scenes are simply buttons pushed that say "winter" or "austere, poverty, struggle street" or "hard man action". The slightly amber and oversaturated look says "happy valley". And so on.

Why do they all look different from pre-DI films? It is perfectly possible to produce a finished film via DI that looks like a pre-DI film (though the effects of digital scanning will be marginally different from the effects of two generations of intermediate duplication). In fact the null closed loop is the test for a good system - if you can scan an image, do nothing to change it, then record it out and make a print that is indistinguishable from the original.

But why would you go through a DI and then do nothing to change the image?
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