RGB PDF's being interpreted as CMYK

[mwdiers]

Context: I am using an HP 9500 as my output device, and have generated my own output profiles. No reference profile was chosen in the creation of the profiles. No white point editing or optimizing either. No simulation profiles are selected.

I have created an RGB color book which we were planning to use to help us pick RBG color values. This book is 144 pages, and spans the gamut RGB values in a 3D HSV grid, where each page is a hue, and contains a grid of colors with saturation as the horizontal axis, and value as the verticle.

Every object in the file is an RGB object. I verified this by importing a page into Illustrator, and further verified this using Enfocus Pitstop in Acrobat Pro.

I was doing some testing to determine which RGB color space best represents the gamut of our device. The problem was - no matter what Input profile (or rendering intent) I picked, the output did not change. This was maddening. "Use embedded profile if available" was NOT checked. The file has no embedded profile.

Finally on a whim, I changed the CMYK input profile a few times. Immediately, the preview changed, and I was getting different results when printing.

Now for the big question: Why the heck is an RGB PDF getting interpreted vie CMYK profiles? It is almost as if Colorproof XF is first converting the PDF to a CMYK TIFF, and then ripping that TIFF.

I have attached a sample page from the book. The same page I was using for testing.

[mwdiers]

A couple of updates:

If I convert the PDF to a TIFF from Acrobat 6, then Colorproof XF will properly render the file as an RGB document.

I converted the document to postscript, and eps, using a variety of settings. In every case, the file was pre-rendered as CMYK, and treated as such. Therefore, this is not just a PDF issue. It is a Postscript issue.

I also attempted to import the PDF into Illustrator, and save it back as a PDF, version 4. Same result.

[HolgerD]

Hi.

Like 5.01 XF is not able to process RGB PDFs by default in RGB colorspace.
The reasons are:
1.) for proofing there is normally no need to process RGB data, because most of the data are CMYK
2.) you need to specify the colorspace of a document rendered by CPSI BEFORE you sent it to the RIP. But you cannot determin the colorspace of a PostScript, PDF or EPS. It can have a lot of colospaces at the same time, and it depends on the settings inside of the document, which one is used.

Nevertheless you can RIP RGB PDFs properly with XF. Inside of the CPSI plugin there is a hidden feature, but you cannot select it by the UI.

Please do the following:
- shut down the XF server
- open up the workflow ticket of the workflow weather you want to process the RGB PDF
- add the following key to the section workflow
<ForceRGB type="int">1</ForceRGB>
- save the ticket and restart the XF server.

Now, ALL of the PDFs, PostScript, etc, will be processed as RGB in that workflow

Hope this will help.

Holger

[mwdiers]

Thank you, that worked!

We are using the HP 9500 as a production device, and your RIP was the only option we had. No one targets this machine for production. Therefore, though it be a proofing RIP, for our purposes it serves well for production as well (with the side benefit of using the printer as a proofing device, when necessary).

I am more familiar with Onyx Postershop, which allows a Postscript file to have a mix of CMYK and RGB objects, and have each interpreted properly according to the profiles which the operator specifies. In addition, it allows one to select different profiles for vector and images. (likewise, rendering intent).

It would be nice to have such features as that in Colorproof, but we can work with Colorproof, so long as we have the ability to force a PS to be interpreted RGB. It just means more Desktop work upfront.

Thank you again.

--------------
Martin Diers
Technical Manager
The Bernard Group
Chanhassen, MN USA