Graphics Programs Reference
In-Depth Information
How the Policies Differ The primary difference between the Preserve
Embedded Profiles and Convert to Working (RGB/CMYK/Gray) policies is the
default behavior of a warning dialog presented to the user if the Profile
Mismatches: Ask When Opening is on. In addition to warnings and default
behaviors, the policies deal with the issues resulting from document spe-
cific color; pasting data from image to image. Since it is possible to have
documents open in various color spaces at the same time, it's important
to consider the ramifications of copying and pasting data (or using drag
and drop) between different documents with different color spaces. If we
have two documents open, one in Adobe RGB (1998) and one in Color-
Match RGB, and we wish to copy and paste data from one to the other,
it is important to control what happens to the pasted data. Does the
pasted data get converted to the document color space or is it left
untouched? Photoshop allows us to control these options by applying the
Ask When Pasting check box. It's a very good idea to have all three warning
check boxes applied so that the resulting warning dialog boxes inform us
of the various options available.
The color policy tutorial illustrates that when the warning check boxes
are applied, the actual policy selected plays a minor role. That is, the
policy selection alters the default radio button only in the warning dialog.
In other words, when a warning dialog is presented to the user, the policy
selected controls one of the three possible options by default, providing
a simple keyboard selection to accept, or if necessary, picking a different
option. Where polices can get dangerous is when no warning check boxes
are applied! In this case, color space conversions can take place without
a warning. By removing any kind of warning we can greatly speed up
handling of documents. The downside is that, unknown to you, conver-
sions might be applied. I mention this so that users who need a guaran-
tee that nothing can affect their documents behind the scenes understand
the importance of the warning check boxes.
See Chapter 9, Tutorial #5: “Color Policy.”
Sidebar
Convert or Preserve? You might be wondering about when to convert or preserve the color
data in a document. If documents are coming from various sources with embedded profiles pre-
serving the profile is usually the best tactic. If I supply someone with a tagged document in
ColorMatch RGB, I do so for a reason. Therefore, someone opening my files would have little
reason to convert the data into a different RGB working space. Converting from a smaller to a
larger gamut working space usually provides no benefit. That is, if I provide a document in
ColorMatch RGB and someone blindly converts into Adobe RGB (1998), the color gamut has
not increased, Photoshop has spent additional time conducting a conversion, and the original
data might undergo some degradation. Every color space conversion will produce some round-
ing errors due to the math involved. Although you can do this on high-bit (16-bit per channel)
files, and since Photoshop conducts all its color space conversions with 20-bit accuracy, this
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