|
Spot colors can be used with CMYK
or Multichannel documents intended for print to add
additional colors, create "bump plates," and to
control varnishes. They can add a bunch to your
printing bill. Or they can reduce your print costs -
think about using black and a single spot color for
some projects.
Spot color channels are designed to
provide a channel for additional inks to be used in
commercial printing. The location in the image where
the ink should be applied is stored in the spot
channel. A separate printing plate is generated, and
an additional run through the press is required. This
usually increases the cost of the print job.
If you need to ensure an exact match
for a corporate logo, you may want to use a spot
color. Another typical use is extending the color
range of an image beyond those that can be produced
using the CMYK inks. Neon and metallic colors can be
added with spot channels. Spot channels can also be
used to identify areas of an image over which a
varnish will be applied.
A spot channel is added to the image -
and to the Channels palette - using the Channels
palette menu command New Spot Channel. If you have an
active selection in the image, the spot channel will
automatically be created from it. With no active
select, an empty channel is created.
The command opens the New Spot Channel
dialog box. In the dialog box, click the color swatch
to open the Color Picker. Spot colors are typically
selected from a Custom book in the Color Picker.
The name of the color selected is
automatically updated in the New Spot Channel dialog
box, as is the swatch. Solidity refers to how the spot
channel will be viewed on screen - it has no effect on
printing at all. When set to 100% solidity, the spot
color will be completely opaque on screen in areas
where it will be printed at 100% ink density. (Lesser
tints of the ink, identified in the channel by gray
values under 100%, will be proportionately reduced in
opacity.) Setting the solidity to 0%, however, does
not make the spot color transparent. Rather, it simply
reduces the opacity of the spot color areas. Solidity
has no effect when the spot channel is the only
visible channel.
The Solidity field is previewed live
in the image (if you're creating the spot channel from
a selection), so you can experiment with various
settings before closing the dialog box. You can also
re-open the spot color options to change the setting
by double-clicking the spot channel in the Channels
palette.
There are three basic techniques for
identifying where a spot color will be applied:
· Make a selection in the image before using the New
Spot Channel command.
· Create the new spot channel, then use Photoshop's
various tools and commands to create a grayscale
representation of the spot color.
· Make a selection with one or more channels active
and copy, then paste into the spot channel.
Spot channel information does not
appear in the Layers Palette. You edit the spot color
information by editing the spot channel. Remember that
the spot channel is a grayscale representation (even
when the Preferences are set to show it in color).
Paint with shades of gray, not the spot color itself,
in the spot channel. Painting with black produces
areas of 100% spot color tint.
To show on screen where the spot color
will print, the spot channel must be visible in the
Channels palette. It can be made visible by itself for
easy editing (as is shown above), or it can be shown
in conjunction with the composite channel (or any of
the color channels).
Spot channels don't interact with
layers, so adding a type layer in a spot color is out
of the question. Instead, create a type mask in the
spot channel and fill the selection with black. The
Type tool will automatically enter type mask mode when
a spot color channel is active in the Channels
palette.
For 100% coverage of the spot color,
make sure to fill the type selection with black.
Images containing spot channels should
be placed into a page layout program in the DCS 2.0
file format. While the advanced TIFF format supports
spot colors, your page layout program might not
recognize the additional channels or generate color
separations from them.
I've been asked in the past why spot
channels are available for RGB and L*a*b color modes
if they're intended for print. Remember that
conversion to CMYK color mode often happens late in a
work flow. You can add the spot color channels at any
time - they're maintained when you do your final
pre-print color conversion.
In addition, you can use a spot
channel as an interim step in an RGB image. Create the
spot channel, apply the color. Since the spot color is
in a separate channel, it is protected while you
continue editing and adjusting the rest of the image.
Later, use the Channels palette menu command Merge
Spot Channel to integrate that channel into the RGB
channels.
|