Profiles are resources that are available to improve the color
appearance of images. Hardware and software manufacturers provide a variety of
profile options to give users flexibility in controlling image color. Embedded,
workspace, and destination profiles are all available and accessible.
Color Management
Programs like Adobe Photoshop, Illustrator, and InDesign provide a “color
management system” that allows many options for dealing with color
non-generically. Under Color Settings the user has access to Color Management
Policies, Workplace Settings, and Conversion Options to improve the quality of
the flow of color from internal sources that are resident in the software used
to create images, to external resources that produce the final image display.
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| Photoshop color settings dialog box. |
Working Spaces 1.
The working space designates the working color profile to be used for
a particular color model. There
are a number of options are available for each RGB, CMYK, Gray, and Spot color
modes. See theinformedillustrator.com post “Digital Color Spaces” for more information on color
modes.
Color Management Policies 2.
Color management policies oversee the operation of a particular color
model. They handle how color profiles are applied, the moving of color from one
document to another, and they determine if there is a profile mismatch.
Essentially, how the color will behave in an image. Preserve Embedded Profiles
is the default provided and in most cases is the proper selection. Preserving
profiles means that RGB colors will be displayed based on perceptual
appearance, or how they look best in an RGB environment. CMYK colors are
displayed according to the numerical values that will be needed when an image
is translated for output.
Conversion Options 3.
A Conversion Engine is used to select which software to use when
handling the color conversion. Adobe (ACE) is the default setting,
allowing adobe program settings to be used for conversion; but the primary
function involves the “rendering intent” for the colors to be converted. The
Color Conversion Engine uses Intent for the handling of “out of gamut colors”
when rendering colors. There are four rendering options.
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| Conversion engine options in color settings. |
Perceptual Intent
Perceptual, the most commonly used intent, will shift both in-gamut and
out-of-gamut color to generate the best visual appearance for the image. Out-of-gamut
colors are brought in gamut by closest color approximation to optimize colors for improved quality results in the destination display
space.
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| Color rendering intent options. |
Saturation Intent
Saturation focuses on the intensity of highly saturated colors in an
image. Color accuracy is sacrificed for visual emphasis rather than accuracy.
The saturation intent is an option for situations where pseudo color is
preferable to realistic color.
Relative Colorimetric Intent
A popular alternative to perceptual intent, relative colorimetric
matches color to color between a workspace environment and a destination
environment to preserve color consistency. Out-of-gamut colors are changed to
the closest in-gamut color, even when the shift involves duplicating a color
that already exists. Workspace white is matched up with destination space
white.
Absolute Colorimetric Intent
In gamut colors are mapped color to color. Out-of-gamut colors are
remapped to best guess, in-gamut colors. Although relative and absolute
colorimetric intents are similar when it comes to dealing with colors, they
differ substantially regarding white. Absolute colorimetric treats white as a
color that can cause a color shift in the destination space appearance of white,
which may take on a warmer or cooler look.
Black point
compensation preserves the relationship of blacks between the workspace and
destination spaces. Dithering allows the conversion engine to combine in-gamut colors
to best represent out-of-gamut colors.
Applying Standard Profiles
Adobe and other
software developers provide a way to select and apply print profiles. In Adobe
it can be done in the Convert to Profile dialog box, which comes with preset
profiles for many standard destination devices and print surfaces.
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| Convert to profiles dialog bog. |
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| Detail of destination space profile options. |
Using Customized Profiles
The result of
producing prints on a personal printer can be much less certain than in
commercial production, however there are ways to print high quality color with unsurprising,
dependable results.
Custom profiles can
provide even better results than profiles that are available from
manufacturers. What makes custom profiles superior to generic ones is that they
use your own equipment and printing paper to take readings to generate a
profile. So, if your printer’s inkjets are quirky; or you prefer to use third
party inks; or you use hand manufactured or exclusive material papers like
bamboo or canvas; or your livelihood depends on extreme color accuracy; you
will probably want to order a custom made printer profile. There are several
profile companies to choose from, like greatprinterprofiles.com, owned
and operated by photographer Michael E. Gordon. Each provider has different instructions and
applies different methods for generating a custom profile.
Creating a custom
profile print usually involves these steps:
1) Make sure your
monitor is calibrated.
2) Download and
print out target pages.
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| Sample of greatprinterprofiles test target page. |
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| Sample of printerprofilesonline target test page. |
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| Sample of customprinterprofiles target test page. |
3) Ship the printed targets to the profiling company.
4) When received, install
the provided profile into your profile directory.
5) When an image is
ready to print, follow printing instructions, and print.
Custom Color Profile Providers
In The Too Much Information Category
Many profiles are classified as ICC compliant. ICC stands for the International Color Consortium. ICC profiles are
those that conform to the color standards of the ICC, which was formed in 1993. Many devices are set up
using ICC standards. This is essential for consistent conversion from one color
space to another. ICC standards can be applied to classes of input devices, display
devices, and output devices. Algorithmic models perform the transformation
between color spaces, for each device class. They work for device-dependent as
well as device independent color environments. Here’s how ICC works. ICC
operates in a “profile connection space” or PCS space. The PCS space provides
an unambiguous interface between
input and output devices. The interface is either CIELAB or CIEXYZ. These
interfaces are based on tristimulus or RGB color values. The CIELAB system
is based on a positive-negative, or push-pull, color relationship. And CIEXYZ
is based on an X, Y, Z axis coordinate relationship of colors.
