InDesign converting legacy spot colours

Question

Hi there,
I have been supplied a pdf that contains the spot colour Pantone Yellow C. The PDF properties says that it was created in InDesign CC and I have no reason to doubt this. For our own internal prepress  workflow I need to bring the PDF back into InDesign CC and make another PDF. When I do this the spot colour appears in InDesign swatches palette as a Lab Spot colour. Now I know this is down to the introduction of Pantone+ libraries since CS6 but I do not want to print the spot colour, I want to convert it to CMYK. The Pantone Plus book states that this colour should have the breakdown 0%C 1%M 100%Y 0%K however InDesign CC converts this colour to 2%C 9%M 100%Y 0%K which is quite a difference and gives quite a brown tinge through our ISO proofing device. I then forced the PDF open in Illustrator CC and the swatch appears as a CMYK Spot with the correct pantone breakdown. So my first question is why if Illustrator and InDesign CC are using the same Pantone+ libraries do they both interpret the colour differently?
Hopefully you're still with me on this as it has been melting my brain. My next test was to place the supplied PDF into InDesign CS4, when I did this the spot colour came in as a CMYK spot with the correct breakdown. So my last test was to create a new CS4 document and add the swatch colour to my document. I then opened that document in CC and what do you know it preserved the colour as a CMYK spot.
The nature of our business means that we have to bring supplied PDFs back into CC to produce a new PDF but my concern is that will now be incorrectly converting spot colours to the wrong values.
I know you may say go back to the client and ask them to convert the colour but this is not always practical and we may receive multiple PDFs from different design agencies.
If you have any input/solution I would greatly appreciate your feedback.
Many Thanks,
Nik

Answer 1

Hi Rob,
that InDesign document is great. I've just knocked up a quick script to get the values and write them to a csv file. The reason I want a csv file is so I can embed this in my script and just use grep to find a colour and get it's cmyk values.
set cmykSpotFile to POSIX path of ((path to desktop as string) & "Spot_to_CMYK.csv")
tell application "Adobe InDesign CS6"
  set spot_list to every color of active document whose model is spot
  repeat with thisSpot in spot_list
  set colourName to name of thisSpot
  set colourValues to color value of thisSpot
  my updateList(colourValues, colourName, cmykSpotFile)
  end repeat
end tell
on updateList(colourValues, colourName, cmykSpotFile)
  set the beginning of colourValues to colourName
  set recordString to ""
  repeat with thisItem in colourValues
  set recordString to recordString & thisItem & ","
  end repeat
  set recordString to text 1 thru -2 of recordString
  do shell script "echo " & quoted form of recordString & " >> " & quoted form of cmykSpotFile
end updateList
Many Thanks,
Nik