Surely this is a gradient made from Cyan, magenta, yellow or black?
I'm thinking the printers workflow is a little bit old. I thought DeviceN or "nchannel" was only a description of a spot colour? It shouldn't cause any issues? I'm wondering why the printers are even checking for this?
Since I reckon the printers have an older workflow, I think the nchannel is only with pdf 1.6 or higher.
I think if you made a pdf with 1.5 or even 1.4 (transparency is flattened with 1.4) then it shouldn't show up.
And since I think the printers are using ancient workflows (ancient is such a weird word to use) that I think it's probably best to make this PDF flattened.
Always get colour proofs, especially in situations like this.
Exactly what nChannel evidence do you have? Depending upon how you export the PDF, you might end up with content is SeparationBlack. That is effectively equal to CMYK=(0,0,0,k) and should cause no problems with display or any RIP that conforms either to the official PostScript or PDF specifications.
I made the PDF using 1.4 and saw the same result. This is a one color (K) project I am working on. I have attached before and after screenshots/images showing the color of the object in the PDF which I am placing into InDesign, and the after screenshot which shows the NChannel conversion. I have seen the same thing a few times now, and the only common element sems to be that I am placing a PDF into InDesign, and the element in the PD is gray 0% brightness.
Forget PitStop. Use the Acrobat 10 or Acrobat 9 Output Preview Separations and Output Preview Object Inspector functions to see what you really have. If you have content that is SeparationBlack, you are good to go. That is equivalent of CMYK=(0,0,0,k).
I am only up to Acrobat version 8, so I can't use the tool you described. In the preflight report I can see that this only uses one sep (K)
I have also found that NChannel show up only when I place a PDF into InDesign when the PDF contains gray. If I place a grayscale .jpg or .tiff for example, the color comes out exactly the same in the resulting PDF, with no NChannel. The conversion to NChannel only happened using PDFs. I even used PDF optimizer to flatten the PDF first before placing it in InDD, but that had no effect.
Why does InDesign convert the color for GS PDFs, and is there a way to make it stop doing that?
It's already been said, stop using Pitstop.
Use Acrobats tools to see what's really in the PDF.
Perhaps Dov can guide you more on how to troubleshoot this in Acrobat. But Pitstop seems to be the problem here.
i noticed in the OP's post that the printer's REP is making the comment. what does the printer's ART DEPARTMENT think?
i use acrobat 8 and enfocus pitstop 10 to diagnose faults with supplied PDFs at work. It is possible in acrobat 8 to go to the output preview and turn on separations. if the black channel is turned off, what happens? does the page go white (indicating that black was the only colour on the page) or is colour still visible?
I've had PDFs in the past with DeviceN as the OP is describing but am outputting to an Apogee X RIP and the art separates on the black channel just fine.
as to the mechanics of what's going on when making the PDF... no idea.
That should RIP without any problem with the content of that SeparationBlack going to the K channel.
That is correct. In Acrobat 8 when I go to Output Preview and turn off process black, the page is completely blank.
I have also noticed that in InDesign, any objects that have transparency effects such as drop shadows applied to them are NChannel in the resulting PDF. Once again, I see the same result in Acrobat's output preview.
The printer will not accept files that contain NChannel because they say "NChannel... does not convert to gray correctly"
Looks like this inquiry is goint to lead me back to the printer for more details.
Again, I think the printer is too overly concerned or else working with a very old system. I think this is down to the grayscale images or gradients/continous tones.
I was able to rid the Device N by going to PDF optimiser and I ticked the
Under Discard User Data I have ticked
Discard document info and metadata
Discard all object data
Discard private data of other applications
Discard hidden layer content and flatten visible layers
Under Discard Objects I have ticked
Discard embedded print settings
I'm not entirely sure which one cause the DeviceN to disappear.
But it didn't come up again after I did that.
Thank you everyone for your help on this topic. This issue has been resolved. A different printer has confirmed that the N Channel in our files RIPs just fine. As everyone here has said, the issue was not with my files, but with the workflow of the original printer..