Dan Margulis Applied Color Theory

Traditional Camera Separations

   Date: Thu, 08 Dec 2005 21:49:57 -0800
   From: John Denniston
Subject: Where did the black come from

Not too long ago, the 1970’s until early 1990‘s, colour pictures from wire services arrived at newspapers on a glorified fax machine as CMY separations. These were shot to size and registered on a process camera. Because of time restrictions CMY colour was normal at the paper where I worked but in the mid 80’s we started running a black plate almost all of the time. I'm curious to know how the black plate was made and how the amount of black generation was decided since the back shop had no idea what the colours of the picture were until they made screened separations and stacked them on top of white paper in front of a light box.

Regards,

John Denniston
www.dirtbikephoto.com
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   Date: Fri, 9 Dec 2005 17:23:01 EST
   From: Dan Margulis
Subject: Re: Where did the black come from

They presumably shot contone negatives and then contacted through all three to produce the black, thus not getting any image except where all three channels were relatively heavy.

This created a skeleton black, there being no other option. GCR isn't possible without bringing a computer into play.

If you'd like to experiment for yourself, take any RGB image, and apply the red to the green in Screen mode, and apply the blue to the result in Screen mode. The final image after the three blends should be a highly acceptable black channel.

Dan Margulis
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   Date: Sun, 11 Dec 2005 00:19:50 -0800
   From: Rick Gordon
Subject: How Were CMYK Seps Traditionally Generated?

OK. Could someone (with direct personal experience) please clarify how CMYK separations were generated in pre-Photoshop days? What tools were used, and what kind of finessing has become more difficult using current technologies?

Can someone now -- with Photoshop and whatever skills might be brought to bear -- create separations as good as the best-crafted ones in the "good old days"?

Did those old separations still have the same abrupt flattening of CMY values as ink limits were approached?

What are the real "frontier" areas where improvements are need to match what was attainable using the best traditional technologies?

And regarding "human-generated" profiles, is it really the profiles that are human-generated, or is it really the separations? Does customizing values in a legacy Photoshop CMYK setup really make it any more human-generated, than a hand-tweaked ICC profile?

Rick Gordon

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RICK GORDON
EMERALD VALLEY GRAPHICS AND CONSULTING
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WWW:   http://www.shelterpub.com
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   Date: Sun, 11 Dec 2005 10:55:13 -0500
   From: Jim Rich
Subject: Re: How Were CMYK Seps Traditionally Generated?

Rick,

In the 1940s through the 1960s production level color separations were mostly made in a photographic process such as using a process camera or in using a contact frame.  Though there were a few  continuous tone (CT) based scanners.

During that time, there were two different types of color separation methods.

1. The indirect method and 2 the direct method.

Both methods were technically challenging due to the fact there were lots of intermediate films and technical steps. Things like varying camera exposure, handling films, masks and  contact screens in darkrooms, changing RGB and cc filters  and because  CT  and lith film processors are  unstable and hard to control.

The next type of technology for color separations was a drum scanner. These devices were built before the 1930s but hat technology did not really take off until the late 1960s. During the 1970s and 1980s these tools evolved into powerful color separation tools. Then in the 1990s, scanners (drum and flatbed) evolved into lower cost, but high quality desktop tools.

Drum scanners  of the 1970 and 1980's offered features for controlling specific portions of an image such as  neutral gray, image contrast (tone reproduction) selective color correction and detail enhancement (USM).  And provided a way for a skilled operator to make fine tuned high quality color separations. As PostScript and desktop imaging became popular, scanners became more driven by desktop scanning applications such as Photoshop.

In all of these color separation processes, skilled operators were critical to create high quality color results.

As for what finessing is required for creating good color?

At a fundamental level, first and for most, you need to capture the image correctly with a camera. Then if you are using film from the camera be sure the scanner can capture the tones of the image. In the old days of scanning (the 1980) this meant an investment between $100,000 to over $300,000. Today, that might mean buying an Epson scanner for under $500.

Then you need good color skills that include knowing how to use Photoshop (or a scanning app) to control neutral gray, image contrast, selective color correction and enhance image details. And of course you need to  know how to use accurate ICC profiles.

Can someone now -- with Photoshop and whatever skills might be brought to bear
-- create separations as good as the best-crafted ones in the "good old days"?

The short answer is sure. Skilled color pros use Photoshop and the current capture technology to accomplish this all of the time.
 
I was actually fortunate enough to start showing folks how to create high-end color separations with Photoshop  back in 1992. This was straight forward for me, since  I showed up on the Photoshop scene (in 1989) understanding the fundamentals of color reproduction. By that time I had served two apprenticeships,  one for black and white and one for the color camera and then I  spent the 1980's installing color drum scanners.  That type of background meant  I only had to learn the  Photoshop tools and not how to create color separations.  The point is that these are two distinct sets of skills for getting the best-crafted seps using Photoshop.
 
Today,  my  sense is that people show up " with Photoshop and whatever skills " and then expect to get good results when they still need to learn about how to reproduce color images.
 
Did those old separations still have the same abrupt flattening of CMY values?

Some times depending on the operators skills and if the scanner was working properly and if the scanner  had the right sensor technologies.
 
What are the real "frontier" areas where improvements are need to match what
was attainable using the best traditional technologies.

If you are talking about creating color separations, you need to have a good capture device and once you have that, then....my view is that we have been there for a few years and it is not a frontier. In the context of this comment, the only frontier to overcome is getting the right training.
   
And regarding "human-generated" profiles, is it really the profiles that are
human-generated, or is it really the separations? Does customizing values in a
legacy Photoshop CMYK setup really make it any more human-generated, than a
hand-tweaked ICC profile?

Humans use machines to create ICC profiles. Period.

And if you have the right profiling tools you can often get a good color match out of the box. Now if you are using profiles and have a bad image and you expect more from that bad image.... then you need to apply color skill.
 
While you  might be referring to the UI in the Photoshop custom Color Settings where you dial in values, a machine was used to get you to that point of the UI. This allows you to customize a few settings of a profile you generate.

There are reasons to tweak a profile such as to make a small color correction or to make a small color change to match another device. However, these days I see less and less reasons to do profile editing.
 
Nothing is perfect in  life. IMO, ICC profiles are a great help to easily keep a system optimized. They are easy to create   and do a great job to help all levels of end-users quickly  create high quality color matches.

But eyeballs (and color skill), are a big help too.

If there was a  theoretical battle going on about which is better, icc proflies or eyeballs. my comment (and experience) would be that you can get to a  high quality color match a lot more quickly using  both.

Mileage may vary.

Jim Rich
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   Date: Sun, 11 Dec 2005 22:09:00 EST
   From: Dan Margulis
Subject: Re: How Were CMYK Seps Traditionally Generated?

Rick Gordon writes,

OK. Could someone (with direct personal experience) please clarify how CMYK
separations were generated in pre-Photoshop days? What tools were used, and
what kind of finessing has become more difficult using current technologies?

Drum scanner operators made their own profiles, which were generally called "presets" in those days. Each make of scanner had slightly different profile-editing capabilities. Typically they might have five-point curves for each channel, plus a version of Photoshop's Selective Color on steroids, enabling precise targeting of specific color ranges. Because of computing limitations they did not have as much control over GCR as one would like, typically only a heavy and a light setting.

Because the object of the game was to avoid having to color-correct on an expensive workstation, when each image was scanned, a profile was loaded (or sometimes the scanning house had only one basic profile) and then edited for each original other than gang scans, so that profiling and color correction were joined in a single operation.

Can someone now -- with Photoshop and whatever skills might be brought to
bear -- create separations as good as the best-crafted ones in the "good old
days"?

With Photoshop only and without any plug-ins, no, although Custom CMYK is good enough for most purposes.

Did those old separations still have the same abrupt flattening of CMY
values as ink limits were approached?

Similar flattening.

What are the real "frontier" areas where improvements are need to match
what was attainable using the best traditional technologies?

Changing the CMYK-phobic mindset of the Photoshop team to see if they can be motivated to produce software at least as good as what was available in 1985 on machines running with 32K of RAM with profiles stored on 8-inch floppies.

And regarding "human-generated" profiles, is it really the profiles that
are human-generated, or is it really the separations?

That's just semantics. The profile governs the separation.

Does customizing values in a legacy Photoshop CMYK setup really make it any
more human-generated, than a hand-tweaked ICC profile?

A profile made in Custom CMYK *is* an ICC profile. If what you're asking is, is there a technical advantage in entering all values by eyeball as the old scanner operators did, as opposed to using machine measurements as a starting point and editing from there, no.

Dan Margulis
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   Date: Mon, 12 Dec 2005 00:10:51 -0800
   From: John Denniston
Subject: Re: How Were CMYK Seps Traditionally Generated?

Hi Rick,

I don't know how far you want to go back but at the Vancouver Sun, where I worked briefly, they had a display case of old cameras and one was a 4x5 colour camera from the 1950's which had places for three film holders. The image was split into three by mirrors behind the lens so the B&W film in each holder could be exposed at the same time through a different colour filter in front of each sheet of film, much like Technicolor movies. I was told that positive separations were made to size on photographic paper from the negs using an enlarger which were then shot on a process camera.

The camera was used for scenics, portraits, slow moving feature pictures.

 Regards, John

John Denniston

www.dirtbikephoto.com
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   Date: Mon, 12 Dec 2005 11:32:52 -0000
   From: Stephen Marsh
Subject: Re: How Were CMYK Seps Traditionally Generated?

Rick Gordon writes:

Did those old separations still have the same abrupt flattening of
CMY values as ink limits were approached?

Many old 'raw' prepress scans were often UCR with high ink limits (360>) and a skeleton K plate, very raw scans indeed, not suitable for say SWOP where the ink limiting is more noticeable. Comparing an old style sep that is ink limited to 300% to the new methods should be similar in the deep shadows.

What are the real "frontier" areas where improvements are need to
match what was attainable using the best traditional technologies?

For me, how about blue instead of purple, red instead of orange etc? If it is just a case of using XYZ instead of LAB in the profile, why is this not done? Even Photoshop custom CMYK freaks out with intense primary blue RGB image colours, for example. So, even with separation tables, the old prepress guys like Crossfield were ahead of ICC profiles today when it comes to 'out of the box' colour solutions that put you 90% there, with an average scanner operator (there was set-up time, just as with ICC profiling and ).

High end prepress scans (not Photoshop Custom CMYK seps)used to match the art as close as possible within the reproduction process and out of gamut colours such as blue did not come out as purple, not so today if a simple push button rgb > cmyk profile conversion is made in many cases with no thought.

I would also like flexibility in UCR/GCR/ink limits/dotgain. All that custom CMYK can do and more (UCR needing more than one setting), with 'proper profiles'. Smart black content/channel handling.

Stephen Marsh.
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   Date: Mon, 12 Dec 2005 18:45:54 -0400
   From: Lee Clawson
Subject: Re: How Were CMYK Seps Traditionally Generated?

on 12/11/05 11:09 PM, Dan Margulis at Dan Margulis wrote:

Dan, A few added comments to your response to Rick Gordon.....

.....Because of computing limitations they did not have as much control over
GCR as one would like, typically only a heavy and a light setting. I don't
recall GCR, but the Crosfield had its own (English) version which reminded me
of UCR/UCA. A edit was available to tell the scanner the amount of the UCA/UCR
to apply (35% when used).

We used a separate calibration edit for the black channel. It allowed you to set for total amount of black, when it started and ended and the shape of the curve. Combined these edits made for a flexible set up.

One thing that impressed me more than anything was the built-in software run in default mode. I had a tech guy who was color blind who would enter the Wht/Blk points by density numbers (readouts displayed on the keyboard) run the remainder at default and get decent results.

Because the object of the
game was to avoid having to color-correct on an expensive workstation, when
each image was scanned, a profile was loaded (or sometimes the scanning
house had only one basic profile) and then edited for each original other
than gang scans, so that profiling and color correction were joined in a
single operation.

This work-flow became so ingrained that the change, when it came, seemed like we were wasting time on the computer.

What are the real "frontier" areas where improvements are need to match what
was attainable using the best traditional technologies?
 
Changing the CMYK-phobic mindset of the Photoshop team to see if they can be
motivated to produce software at least as good as what was available in 1985
on machines running with 32K of RAM with profiles stored on 8-inch floppies.

I'll second that (except I hate the 8 inch floppies).

Understanding the user manuals left a lot to be desired but the the design of the software for color edits and the integration of software/hardware was a pleasure. I don't find anything in particular missing from Photoshop yet the way things are implemented and depth of user control are sure not the same.

Lee Clawson
2/\V/\7 Studio
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   Date: Mon, 12 Dec 2005 20:54:09 -0500
   From:John Castronovo
Subject: Re: How Were CMYK Seps Traditionally Generated?

Such split beam cameras went a lot further back than the 50's. Go back to the teens and the 20's, before they had color film, and seps were made directly on process cameras that shot from flat art through filters directly onto sensitized plates. The image was broken into dots using an etched glass line screen behind the lens.

john castronovo