I have 2 duotone images created in Photoshop and linked into an Illustrator file to create a book cover. We have moved the book to a different printer and they need the cover to be CMYK. When I change the mode in Photoshop from Duotone to CMYK it changes some areas to gray and does not retain any of the pantone color in those areas. Can anyone tell me how to get the duotone to change to CMYK and still look the same?
#1
Try converting first to RGB and then to CMYK.
#2
it depends on what colors make up the duotone.
#3
Define "gray".
If by that you mean the color becomes duller, then you may be dealing with an out-of-gamut PMS color (which defines a large percentage of PMS colors) being brought into your CMYK space in accordance with your rendering intent.
This is unavoidable.
However you might like the results better if you:
Choose mode>multichannel.
In the resulting black channel window (here I assume black is one of your colors) select all, and copy.
Open a new document, changing the mode to CMYK, target the black channel and paste.
Then go back to the channel window for thew PMS color in the multichannel file and select all, and copy.
In the new doc use the channels palette flyout to add a new spot channel in the appropriate PMS color, and paste.
Now in the channels palette flyout, choose "merge spot channel".
This bypasses color management and instead of using the Lab values of the PMS color to derive the CMYK numbers, uses the generic CMYK values provided by Pantone.
Your mileage may vary.
#4