Adobe PHOTOSHOP 5.0, User Manual, Page: 105 / 400

97 ADOBE PHOTOSHOP 5.0
User Guide
The Ink Colors dialog box displays the various
combinations of CMYK and the CIE coordinates
measured for each. CIE coordinates are an inter-
national color definition standard supported by
PostScript Level 2.
By default, the Ink Colors dialog box defines colors
as Y (lightness), x, and y values. The default ink
sets are calibrated for viewing conditions of 5000K
(when viewed under D50 lighting), 2
°
field of view.
Note: Colors appear slightly different based on how
much of the eye’s field of view they cover. The CIE
has defined two standard ways of measuring color
coordinates, one based on colors filling 10
°
of the eye’s
field of view, and one based on colors filling 2
°
of the
field of view. Photoshop uses the 2
°
field of view
standard.
4
If desired, choose L*a*b Coordinates to enter
the color box coordinates as Lab values rather than
Yxy values. Use this option if your colorimeter
only has Lab readouts.
5
Using your printed CMYK proof, take a reading
of the color values using a spectrophotometer or a
colorimeter, and then enter those values in the Ink
Colors dialog box.
Alternatively, you can click the color box of the ink
color you want to adjust and then adjust the color
on-screen until it matches the patch on the color
proof.
6
If desired, choose Estimate Overprints to
automatically estimate the overprint colors (MY,
CY, CM, and CMY) using the CMYK and white
values you entered. This is useful if you don’t have
a proof.
7 Click OK.
Converting to CMYK
To print a color separation, you convert an RGB,
indexed-color, or Lab image to a CMYK image.
(PostScript Level 2 color printers can interpret and
print Lab images.) The conversion splits the RGB
or Lab colors into the four colors commonly used
for printing color separations: cyan, magenta,
yellow, and black.
Note the following when converting an image to
CMYK:
•
Be sure to save a copy of your RGB or indexed
color image in case you want to reconvert the
image.