I have written a number of articles on color over the years.
This is updated as of 2005. I started working in the field of
graphics before color profiles even entered the arena. I remember
when many programs, such as Adobe Illustrator, used manual
calibration to calibrate the monitor inside a specific program. I
wish many of these programs still had that as an option, because
many pre-packaged profiles simply don't work. For example, I have
two Viewsonic Professional Series P95 f monitors, and two P95 f+
monitors. None are exactly alike. This is normal for a monitor.
Thus, if I only used a pre-packaged profile, and didn't tweak each
a little differently, it wouldn't do me a lot of good. Plus, as the
monitors age, their color will change. To create a correct profile,
I would have to use special equipment; and I do not mean just the
color calibrating software that comes packaged with many monitors.
Let me first state something that is unfortunately true. The same
printer or scanner with the same driver version on different
operating systems will produce different colors. This is a real
problem. For example, I had my Epson 1280 adjusted under Windows
2000 to my satisfaction. No matter what I do, it will not interpret
color correctly under Windows XP. Here is how I use the tools
available to me at home to calibrate my monitor. This method has
worked for me for years even though it has changed slightly as the
programs have changed. I will use Photoshop CS2 to demonstrate.
However, this works in other programs since it is program
independent. I am working in RGB. However, at the end of this
discussion, I will note some facts about my experience with CMYK in
this home type of environment. The first step is critical. The
monitor must be able to produce a neutral gray screen. Here is a
way to tell [if you use a PC, don't use fancy wallpaper] go to:
property>appearance>desktop>advanced.
To know if the gray is correct, get an outside source like a
photographic 18% gray card, or any medium gray card that is
absolutely neutral gray. If your screen is not neutral gray, your
colors will always have a cast to them. If you need to correct your
screen, use either the software that came with your monitor or with
your video card. I am not talking about calibrating your monitor;
all I am recommending is that you make your monitor screen a
neutral gray. Once you do that, the colors should line up properly.
At least, I have never known them not to unless your monitor is
overly bright or overly dark or just plain bad. This is not
scientific. After years of doing this, I can tell in my gut what I
need to do. These are just hints I am sharing to help you get
there. I cannot tell you if your monitor is too light or too dark.
We all work differently. That is why we choose different profiles.
The same color profile will appear differently on different
monitors especially if the brightness levels are different. Having
the light in your room at a medium brightness and not shining
directly on the monitor is also important keep it consistent. I
will detour and discuss light now, since it will be important soon.
Light is many difference colors. Daylight has more blue in it than
does a normal incandescent light bulb. When I am looking at color
swatches, for example, I am looking at them under a medium light
and near my monitor, which projects a different light. There will
be some difference in color between the swatches and those on the
monitor because of the reflectivity of the printed paper, and the
differences in light. However, the difference should be minimal. If
I were working near a window, there would be another difference in
color. If you look at a print under a regular light bulb, it will
look reddish. Under some fluorescent, it will look green. If there
is a black and white grayscale in it, the gray should be a neutral
gray under mixed light daylight plus incandescent. I have found
that at home the best way is to take a print, or anything that is
in color, and look at it near a window as well as a table lamp. We
are neutralizing the light to some degree. Again, we are not being
scientific, but I have found this method produces good results.
Learn to look at colors and see how they change with lights. Once
your monitor is a neutral gray, then you can go into your
individual programs and choose a color space to work in. In the
last two versions of Photoshop, I have used the same RGB color
space, sRGB IE 661966-2.1. I have found that space most accurately
represents my colors on my screens with the way I have set up my
overall monitor, i.e., intensity of light and neutral grayness of
the screen. I have created a montage of images to use as a
reference. This montage is comprised of Trumatch
swatches and pictures of objects I have at home, as well as two
images I created. I first created little boxes to be filled in by a
Trumach color. In Photoshop I double clicked on set foreground
color and then clicked on color libraries.
From there I accessed the Trumatch library. Once there, I typed in
the letters and number; like 6a for red and proceeded from there.
I could have used Pantone or any library where there was also a
separate book of swatches. The gray scale was just a matter of
typing in 100%, 90%, etc. using grayscale as my color mode.
Since I am not working with a service bureau and needing to produce
color separations, I work in RGB mode and leave the default setting
for CMYK alone. To decide on the appropriate RGB color space, it is
important to turn off embedded profiles at this point, even if you
decide to use them later. If you don't, your images will not change
in color as you change RGB profiles. I then checked all the
profiles available in Photoshop and compared them to the swatches
and the colors of the other external sources I was using as a test
base.
I kept a list of the ones that most closely resembled the swatches
as a whole. It is important to use mixed-colors (those under the
gray scale in the image above), because I have found that it is
harder to tell the saturation level of the RGB, CMY colors if they
are the only ones used, and that can make a difference. When I
first started, I only used those colors. Then, when I went to
print, the colors were not correct. It was because of the
saturation levels. A color that looked OK on the screen could be
too saturated and overpower another. Usually what you will find is
that one color might be off a little, and in trying to fix that by
choosing another profile, others will then be off. So, go with what
looks best as a whole on your monitor using the swatches as well as
all the objects. While I did all the above testing in RGB, I took a
blank template and made sure it was in CMYK color mode. I then went
through the process of filling in the swatches in CMYK mode, and
brought in the bottom images, which converted them from RGB to
CMYK. I looked at them on the screen beside an RGB test and an RGB
test that I converted to CMYK. The images of figures and pictures
were all originally created as RGB so even in the document created
in CMYK mode, those images had to be converted when copied and
pasted. All the color and gray scale bars in first image to the
left were created in CMYK mode. The bars in the middle image were
created in RGB mode, and those on the far right were created in RGB
mode and converted to CMYK mode. A screen capture was taken of each
image. There were no embedded profiles.
Next we need to look at the relationship between the different
colors and what they mean. The relationship between Red
Green Blue and Cyan Magenta
Yellow blacK, is often hard to understand. Both
color spaces are interrelated.
Notice how, no matter what mode you are in, the colors created
using CMYK percentages will always appear the same. When you create
colors using RGB, as you add them together you get white. When you
remove all color, you get black. In the chart below, assume that
for RGB, when you are creating new colors, you are adding together
255 of each color. In the CMYK section, you are adding 100% of each
color to create the new color.
However this is all theoretical. In the real world, it does not
happen that way; and that is part of the problem and confusion
about colors. Look at the screen captures from Photoshop CS2 mixing
palettes. These were created in RGB color mode. Look at the RGB and
CMYK boxes only. The top line shows colors made using RGB numbers.
The second line shows colors made using CMYK numbers.
The same holds true for the next group of colors.
RGB colors are colors from light think in terms of the light from
your monitor while CMY[K] colors are colors from ink think in
terms of a printer. In light, if you add Red, Green, and Blue
together you will get white light. The absence of all colors is
black. Whereas in CMY, it is a building up process, Cyan, Magenta,
and Yellow added together create Black [dark mud brown], and when
all are taken away, you are left with white. Since the back is not
really black, we add blacK to our CMY printing colors. In
very simplistic terms, and without going into any scientific
explanations; one works in an RGB [light] space, eventually using
CMYK colors if the documents are to be printed. If the mode is RGB
or CMYK, you are still using the printers [CMYK] colors if the end
result is printing. The web has other problems, which I will not
even try to discuss here because this is a discussion of RGB and
CMYK color modes and not Indexed color.
All supporting images are copyright, and
cannot be
copied, printed, or reproduced in any manner without written
permission from the artist.
- The Paula Sander's Report is a regular
Renderosity Front Page featured column, where Paula investigates
and comments on graphic software, techniques, and other relevant
material through her reviews, tutorials, and general articles.
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