Adobe Photoshop CS4 - Manual (Page 159)

152 USING PHOTOSHOP CS4
Color management
Last updated 1/10/2010
About rendering intents
A rendering intent determines how a color management system handles color conversion from one color space to
another. Different rendering intents use different rules to determine how the source colors are adjusted; for example,
colors that fall inside the destination gamut may remain unchanged, or they may be adjusted to preserve the original
range of visual relationships when translated to a smaller destination gamut. The result of choosing a rendering intent
depends on the graphical content of documents and on the profiles used to specify color spaces. Some profiles produce
identical results for different rendering intents.
In general, it is best to use the default rendering intent for the selected color setting, which has been tested by Adobe
Systems to meet industry standards. For example, if you choose a color setting for North America or Europe, the
default rendering intent is Relative Colorimetric. If you choose a color setting for Japan, the default rendering intent is
Perceptual.
You can select a rendering intent when you set color conversion options for the color management system, soft-proof
colors, and print artwork:
Perceptual Aims to preserve the visual relationship between colors so it’s perceived as natural to the human eye, even
though the color values themselves may change. This intent is suitable for photographic images with lots of out-of-
gamut colors. This is the standard rendering intent for the Japanese printing industry.
Saturation Tries to produce vivid colors in an image at the expense of color accuracy. This rendering intent is suitable
for business graphics like graphs or charts, where bright saturated colors are more important than the exact
relationship between colors.
Relative Colorimetric Compares the extreme highlight of the source color space to that of the destination color space
and shifts all colors accordingly. Out-of-gamut colors are shifted to the closest reproducible color in the destination
color space. Relative Colorimetric preserves more of the original colors in an image than Perceptual. This is the
standard rendering intent for printing in North America and Europe.
Absolute Colorimetric Leaves colors that fall inside the destination gamut unchanged. Out-of-gamut colors are
clipped. No scaling of colors to destination white point is performed. This intent aims to maintain color accuracy at
the expense of preserving relationships between colors and is suitable for proofing to simulate the output of a
particular device. This intent is particularly useful for previewing how paper color affects printed colors.
Advanced controls in Photoshop
In Photoshop you display advanced controls for managing color by choosing Edit > Color Settings and selecting More
Options.
Desaturate Monitor Colors By Determines whether to desaturate colors by the specified amount when displayed on
the monitor. When selected, this option can aid in visualizing the full range of color spaces with gamuts larger than
that of the monitor. However, this causes a mismatch between the monitor display and the output. When the option
is deselected, distinct colors in the image may display as a single color.
Blend RGB Colors Using Gamma Controls how RGB colors blend together to produce composite data (for example,
when you blend or paint layers using Normal mode). When the option is selected, RGB colors are blended in the color
space corresponding to the specified gamma. A gamma of 1.00 is considered “colorimetrically correct” and should
result in the fewest edge artifacts. When the option is deselected, RGB colors are blended directly in the document’s
color space.
Note: When you select Blend RGB Colors Using Gamma, layered documents will look different when displayed in other
applications than they do in Photoshop.