If you click on the Functions ...
button, a further dialog
box appears in which you can modify the complete colour list in
various ways.
The left half of the dialog controls a Colour system converter. If
you want to convert all colours that are present in a given colour
system to another colour system, use the functions in this area. If,
say, you wish to convert all RGB colours, click on the corresponding
radio button at left under Source
and on that of the desired
new colour system (such as CMYK) under Target
on the right. A
click on Convert colour system
button converts directly all RGB
colours of the whole document colour list to CMYK colours. You will be
returned immediately to the Edit colour list main dialog.
If you wish to sort the whole colour list, then you have various
sorting modes available in the top right panel. Select the desired
mode and click on Sort colour list
. All colours of the document
colour list will be resorted immediately and you will be returned to
the main dialog once more.
The Convert grey to K
panel is a special form of the Colour
system converter. It converts all grey values in the document colour
list (i.e. all values in the K
system, all identical values in
RGB and CMY colour systems) into the correct, pre-separated CMYK
colour values. This means, for instance, that K30 will be turned into
C0 M0 Y0 K30. Simple switching of the colour system from K to CMYK
would produce C30 M30 Y30 K0 instead. The result of this would be that
when imagesetting this grey value, nothing at all would appear in the
black separation film while 30 % would be output in each of the three
C-M-Y colour separations films. In itself that wouldn't be too
serious, but with offset printing, for instance, the result is never
really a 30 % grey but a muddy brown between 40 and 50 %. A simple
switching of R0 G0 B0 (RGB black) to CMYK would result in
C100 M100 Y100 K0, which offset printing would reproduce as a muddy
black made up from cyan, magenta and yellow, whereas a 100 % black in
the black separation film was actually desired. The Convert grey to K
converter will produce the required result by converting the
above-mentioned RGB black correctly to C0 M0 Y0 K100.
So for safety's sake, don't forget to make use this function of the grey to K converter before outputting the data for imagesetting.
