ColorNews Issue #5

Metamerism

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C H R O M i X C O L O R N E W S

Issue #5
June 6, 2002
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Welcome to ColorNews, a periodic update on all things related to Color
Management. Please let us know what your interests are so we can address
these concerns in our coming issues. We apologize for the delay from our
last newsletter, many exciting changes have taken place at CHROMiX and
we will be covering them over the next few newsletters.

ColorNews covers newsworthy items including new product releases and
updates, and interesting, informative web sites. Each issue will
include a feature article covering an aspect of color management such
as profiles, workflow, and so forth.

In a visit to CHROMiX.com or profilecentral.com, you opted to receive
this newsletter. You may have also heard Steve Upton speak and
requested more information. If you have received this message in
error, we apologize. We value our relationship with you and do not
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how to unsubscribe, or how to become a sponsor.

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Table of Contents
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1. CHROMiX News
2. Color News
3. New Releases
4. ColorFAQs - this month's FAQ is on Metamerism, or
Things That Go Weird in the Light
5. ColorNews Administration (feedback, subscriptions, etc.)

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CHROMiX News
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There have been so many changes at CHROMiX since the last newsletter that it is worth mentioning them here:

- our Website has been completely rebuilt reflecting our new corporate look and brands. If you haven't been by in a while, please come take a look. We think you will like what you see.

- ColorThink 2.0 is nearing release - thank you all for your excitement, feedback and patience. We will let you know the moment it is ready.

- ColorGear.com is the new name for our online store which was the first of its kind and remains the most comprehensive color management store available. Please pay us a visit at <http://www.chromix.com/colorgear> (domain setup to be completed soon for colorgear.com) Also! call us toll free at 877-colorgear with any questions or orders!

- ColorValet is the new name for our ground-breaking remote profiling services. Print profiling is going strong and we have a new kit for free download that has been updated for Photoshop 6 (7 to follow soon) and includes larger targets for even more accurate profiles. ColorValet profiles are the highest quality profiles you can get, require only one printed target and are 100% guaranteed - give them a try, you have nothing to lose!

- ColorSmarts - want some? - we organized our technical tips, glossary, ColorNews back-issues, training, technical support and other services under one brand. Come search the most comprehensive technical database on color management topics - for free! Get smart!

- ProfileCentral is undergoing major changes under the hood. Please let us know if you have any profiles you wanted hosted. We'll notify you when the new changes are released.

Staffing - we have had several staffing changes over the last months but one we are really excited about is the addition of Rick Hatmaker. Rick has many years experience in the computing, digital imaging and color management markets and is now acting in a sales and system consulting role for us. Call him toll free at 877-colorgear x7 or hatmaker(at)chromix.com. He's eager to put his talents to work solving your color problems.

Offices - CHROMiX has moved into larger offices in Seattle to accommodate our growth. Our mailing address and phone numbers remain the same but the new space will accommodate our expanding profile-building lab and we are planning on holding small hands-on seminars there as well. We'll let you know more as it develops.

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Color News
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- Epson announces a free plug-in for users of Adobe Photoshop 7.0,
6.0, and Photoshop Elements 1.0, that will offer print imaging
matching for people owning a print image matching-enabled digital
camera and photo printer. Go to
support.epson.com/webadvice/wa0306.html.

- Court of Appeals finds in Apple's favor in ColorSync case brought
by Imatec - again! The Court upheld the lower court's decision
stating that the color management software did not infringe on
Imatec's patents, finding that Dr. Hanoch Shalit, president and CEO
of Imatec at the time the suit was filed, and his company did not own
the rights to the patent in question. A relief for our friends at
Apple to have this finally in the past!

- A little ColorSync info - in the control panel, for any of the
popups, hold the cursor over a profile name and a balloon will appear
showing the filename. This will only work if the file name is
different from the description name - but, all in all, a very handy
tool!


We are always happy to answer any and all questions you might have.
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New Releases
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GretagMacbeth has made many announcements over that past few months including:

- Eye-One UV - the popular Eye-One system is now available with a UV filter to compensate for brighteners in papers. The UV filter cannot be removed however so the Eye-One is available in UV or nonUV configurations
- Eye-One Monitor upgrade path - you can save 10% on Eye-One Pro/Match bundles and keep your original Eye-One. Contact us for more details
- ProfileMaker 4 has been released. With an updated Editor, tuned ColorPicker, Multicolor module and other improvements it is a winner. Upgrades from 3.x are $389

ColorVision has released LCD capable versions of their popular Spyder monitor calibrator. The new instrument can calibrate and profile CRT and LCD displays and starts at $259.

- X-Rite and Monaco have combined forces to work on a Mac-compatible
color management solution that includes Monaco's MonacoPROOF software
and X-Rite's spectrophotometers. For more information go to
<http://maccentral.macworld.com/news/0108/21.color.shtml>

- Adobe has released an update for PageMaker ColorSync. This fix
allows you to start Pagemaker 7.0 without receiving the error message
that the app has "unexpectedly quit because of error type 1,010." We
HATE those types of error messages! Go to
<http://www.versiontracker.com/moreinfo.fcgi?id=11615&db=mac> for the
download.

- Jim Rich has written a new book, the "Photoshop 6 Color Companion,"
which promises to be invaluable to us PS6 users. To order, go to
www.gain.net, or call 800-662-3916. The book sells for $50, or $40
if you're a GATF/PIA member.


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ColorFAQs
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Each month, our President Steve Upton will take time to answer questions
we receive on a regular basis. If you have specific questions or
comments, please see below for how to make submissions.

This Month - Metamerism - or Things That Go Weird in the Light.

Have you ever compared two garments in a store and decided they
matched, only to find that when you left the store and went out into
daylight they no longer matched and instead looked quite different?

If so, you have seen an optical phenomenon called metamerism (me 'ta
merizm). Strictly speaking, metamerism occurs when you see two
samples match under one light source (illuminant) and not match under
another.

How can this be?

Well, it comes down to the difference between how an object affects
light, and the color it appears to our eyes. Objects affect light by
selectively reflecting or absorbing light of different wavelengths.
So an object that absorbs most blue wavelengths and reflects most red
wavelengths will usually appear red to our eyes. The actual color it
appears to us is dependent on the spectral composition of the light
reflecting off the object.

Let's say, for example, we have two objects that each reflect red
light in approximately the same way but one reflects blue light while
the other absorbs it. If you put both objects under reddish lighting
(and most indoor tungsten lighting falls into this range) then they
may appear to be very close to the same color. As there is very
little blue light falling on our objects, the difference between
their blue reflectiveness is almost invisible. The red reflection is
about the same so they both reflect similar wavelengths and our eyes
see them as the same color!

This would not be a problem if we didn't have many different colors
of lighting in everyday life.

So let's take our objects outside into mid-afternoon daylight.
Sunlight at that time of day contains considerably more blue light
than indoor lighting. As before, our pair of objects will reflect red
light similarly but one of them will reflect a significant amount of
blue light while the other absorbs it. Our eyes will see the blue
light from one object combined with the red light and we would
probably call the result magenta. Suddenly what we thought were two
reddish objects no longer match at all!

Is this a problem?

That depends. In many ways this very phenomenon is essential to color
reproduction (see "Metamerism as Friend" below), but when colors
"shift" from our expectations, clients stop paying bills, and that is
a problem.

Where will we see this problem in the business of digital imaging?

- Proofs and press jobs failing to match under different lighting.

- Color builds chosen for normal printing failing to match under
unusual lighting. A good example of this is trade show booths and how
they are lit with unusual lights in exhibit halls.

- Two prints using different technologies - such as inkjet vs
photographic print - failing to match under certain lighting.

- A product shot failing to match the product in all lighting conditions.

There are other situations as well.


Is there anything we can do about it?

1) Be aware - this isn't really a solution but it is always the first
step toward one.
2) Choose pigments carefully. Beware of pigmented inks for inkjet
printers (see Pseudo Metamerism below)
3) Control your lighting - both for producing prints and for final
viewing, if possible.
4) Profile carefully

Can color management using ICC profiles correct for this problem?

No... and yes. ICC profiles are typically built using readings
referenced to D50 (5000K) lighting. That means that prints created
using these profiles will look best under D50 lighting. Viewing them
under any other lighting can give unpredictable results. Most
printing pigments and dyes have been carefully chosen to not conflict
with each other or other pigment sets. One exception that is
appearing more and more is pigmented inks for inkjet printers (again,
see Pseudo Metamerism below). Sometimes you can measure printed or
scan/camera targets with a different light source such as D65 in the
calculations. This should make the print viewable optimally under D65
lighting. This is not always successful and requires the appropriate
settings to be available both on the instrument and in the software.
We are continually experimenting with such techniques to find
solutions for our clients.

+-------------------------------------------------------------------+
| A D V E R T I S E M E N T
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| CHROMiX ColorThink - Your brain on color!
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| If you haven't seen ColorThink yet, you're missing the full
| picture! ColorThink is the color management toolset that
| picks up where the other tools leave off. Manage your profiles
| individually or in sets, scan and fix problem profiles (including
| profiles imported from PC's to Macs). Graph profiles in 2D and 3D.
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| ColorThink is $129 in our store and is now available as a free demo.
| <http://www.chromix.com/colorthink>
+-------------------------------------------------------------------+


*** Pseudo Metamerism ***

One closely-related problem cropping up more and more often in the
inkjet printing world is often (incorrectly) called metamerism.

When colorants are mixed carefully in a printer, you can achieve a
smooth, neutral gray gradient from black to white. With most inkjet
printers, the ink combination will include Cyan, Magenta, and Yellow
inks in varying amounts along with Black ink. When properly balanced,
pleasing black and white images can be printed. Many users are also
experimenting with near-neutral imaging such as adding a slightly
blue or sepia tone for effect.

With the fugitive nature of dye-based inks, many users are switching
to pigment-based inks for the vastly improved permanence. After all,
if you are printing and selling works for display, your customers
tend to have the expectation that the work will last beyond 2-3
years. Pigmented inks however, can suffer from a pigment balance
problem which rears its head in a similar manner to the two-sample
metamerism problem.

When a quality ICC profile is created for a pigmented ink set, you
will typically see a good neutral gray gradient. As mentioned above,
ICC profiling assumes the print is viewed under D50 lighting. With
some pigment sets (ie CMYK inks sold and/or used together) the gray
gradient color shifts considerably when viewed under different
illuminants. It is important to note that this is not an expected
color shift but rather a shift that appears strange to the eye. One
would expect that a gray tone viewed under D50 lighting would appear
to be a warmer gray when viewed under warmer, tungsten lighting. The
color balance failure we are referring to here shows up as a green or
magenta cast and is noticeably different than a shift normally
attributed to warmer or cooler light.

Many people incorrectly refer to this phenomenon as metamerism.
Metamerism, however, is specifically defined as a phenomenon that
occurs between two samples. The ink balancing situation does not
involve two samples but rather a balance of pigments in one sample.
Strictly speaking, then, it is not metamerism and we (at CHROMiX)
often refer to the problem as Gray Balance Failure or Color Balance
Failure.

What can I do to avoid Gray Balance Failure (GBF)?

As with the suggestions above there are several things to do to
minimize the effects of GBF.

1) Control your lighting - not always possible, but if you can it is
often the easiest solution.
2) Choose your pigmented ink set carefully. View them under different
lighting conditions to see if they shift considerably. Remember, it
is the combination of pigments that is causing the problem. Some
users have found success in mixing inks from different vendors such
as the black from one set in combination with the colored inks from
another. Needless to say, this route can require extensive testing.
3) Profile for different lighting conditions - as mentioned before,
this is not often very easy to do.

*** Metamerism as Friend ***

After all is said and done, it is fair to say that metamerism is our
enemy, right?

Not so fast...

Metamerism, remember is when an object matches another under a
certain illuminant even though the spectral characteristics of the
two objects differ. The act of balancing three or four colorants
(such as CMYK inks) so they appear to be the same color as an
original object is also based on metamerism. Because of the 3-channel
nature of our eyes, we can get 4 inks to appear to match a real-world
object like a person's face without the spectral characteristics of
the inks resembling the face much at all. This means that the print
and the face affect light differently but appear to be the same color
to our eyes!

This is the basis of digital imaging and printing today. It is fair
to say, then, that without metamerism we would not be able to do ANY
of the imaging we do today! It is only when the balance fails that we
call it a problem. Perhaps a match-failure problem should be called
metamerism "failure" rather than metamerism, but this term does not
seem to be used at all.

In closing...

As with anything in the color management world, being aware of the
problem is half the battle. Now that you know about metamerism and
GBF you can consider it as a contributing factor when things don't
look right.

Also, if you have no D50 lighting under which to view your prints it
is possible they will never look quite right. Invest in controlled
lighting for print viewing. With the many variables in digital color
work that can give you problems, nailing down lighting is considered
a basic requirement for print viewing as well as monitor to print
matching (see ColorNews issue #2).

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ColorNews is edited by Carolyn Hobart (hobart(at)chromix.com).

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