Graphics Programs Reference
In-Depth Information
supposed to provide an idea of the correct values to place as either a single
dot gain setting (in Standard) or the various values to produce a curve
(in Curves). The Separation Options are where I can control such factors
as total ink limits, UCR/GCR, and other black generation options. All are
discussed in detail in Chapter 7; the settings here are quite similar to the
separation settings in products we will investigate for building custom
CMYK profiles in various profile packages.
Sidebar
Custom Ink Settings in the Classic Engine:
It would be unfair not to mention the
Custom
menu that appears at the top of the Ink Colors pop-up menu. As seen in Fig. 2-9, picking this
menu item provides yet another scary-looking dialog. This is used to create a custom ink model
assuming you had the equipment. You'll have to run a test press run to your printer or press
and measure the output using a Spectrophotometer on eight colors plus the substrate (the
paper). You'll need this hardware device and some software that will provide either CIE xyY or
CIELAB values (see Chapter 10). A target will need to be generated that has the eight color
values that need to be entered into this dialog.
You can make a document yourself. Use Photoshop to specify the colors in CMYK (i.e.,
100C/0M/0Y/0K for pure Cyan, 0C/100M/0Y/0K for pure Magenta, and so on). Then load that
color into a rectangle selection of your document large enough to measure. Do this for each of
the eight colors listed. To measure exact dot gain values for each ink, specify each ink color in
the following percentage: 2%-4%-6%-8%-10%-20%-30%-40%-50%-60%-70%-80%-90%.
You should end up with a total of 61 patches to measure (eight for the solid colors plus the
paper white, and then 13 dot gain patches for each of the four inks). After this document is
printed, measure each solid color as well as the white of the paper stock and enter the values
in the appropriate fields shown in Fig. 2-9. Next, select
curves
from the
Dot Gain
pop-up menu
in the Custom CMYK dialog. Enter the values for the dot gain in each field for each ink (see
Fig. 2-10). This method is best used for making a custom ink set for your final output device;
that is, the press the job will be printed on. However, according to Adobe, this works with offset
lithography as well as ink-jets and toner-based devices. You can also use this technique for a
Contract Proofing device. Some printers will be willing to output a small test document on an
unused portion of another print job. Obviously the same paper stock and press conditions for
this test print should match the job you intend to run.
You'll still need to discuss other issues with the printer, such as total ink limit and other
black generation settings, but this technique should get you closer to a good conversion for
final output than using a standard ink model. As you can see in Fig. 2-11, you can save out this
custom ink model as an ICC profile. I have to question the time and usefulness of doing this
as opposed to using the same instruments to measure more patches and build an ICC profile
using a dedicated package. However, Photoshop does have a somewhat simple mechanism for
producing a custom ICC profile using the Classic CMYK engine.
Gray
The Grayscale working space pop-up seen below the CMYK pop-
up is where we pick our preferred Grayscale working space. This selec-
tion allows the option of picking five dot gain settings or two settings
based on gamma (1.8 and 2.2). The two basic modes, gamma or dot gain,
