Conversion to PDF lightens blacks (CMYK)!

Question

Hello,
I noticed that converting a document to PDF with Acrobat lightens blacks in the CMYK space.
In fact, converting that same PDF document once more to PDF lightens blacks once more! This happens whether I select in the Colours option "Convert all colours to CMYK" or "Leave colour unchanged".
In fact, CMY and K are altered in the conversion. In other words, in the process of making the PDF, Acrobat changes the colours even when selecting "Leave colour unchanged" to a point that it's noticeable on screen.
I believe the original file was in RGB colour space - blacks set to R=G=B=0. Opening the first PDF (having gone through 1 pdf conversion: original file -> PDF1) in Photoshop CMYK-16bit mode yields rich blacks (with values for all CMYK). Opening the second PDF (having gone through 2 pdf conversions: original file -> PDF1 ->PDF2) in Photoshop shows pure black (C=M=Y=0, K=100)!
So Acrobat, regardless of the colour conversion setting, appears to convert blacks to rich blacks in the first PDF conversion, and back to pure black (C=M=Y=0, K=100) in the second conversion, which looks a little more grey than rich black.
I have seen this happen in Acrobat 8 and 9, and I am using the Print option (not "Save As") to make the PDF file, choosing "Acrobat PDF" as the printer.
Can someone explain:
1- Why this is happening?
2- How to fix it? (i.e. leave the blacks unchanged through the PDF conversion)
Thanks.

Answer 1

Lisa,
The solution suggested by VAN may work perfectly for you in regard to on-line viewing, but will most likely not work in print.
The solution suggested by Sheila is more general and will also enable proper conversion for prepress PDF's. To do it you'll need to create a custom color map, that remap the RGB-color from Heading1 to the CMYK (or SPOT) color from the logo art.
To create a custom color map in Grafikhuset Publi PDF you simply right-click the Publi PDF icon in the system tray, select the Attended Queue you want to use, and then turn on automatic creation of color maps in the Optimizer section of the pop-up menu. This will prompt you with an interface that allow you to create new spot colors -- next time you print to the queue.
Clicking the "Convert to" field for each listed Gray, RGB, CMYK or other spot color allow you to remap colors exactly as your job require. When finished you can save the color map for later use. You may actually attach it to the queue, so you don't need to enter new information each time you print (If you attach it to the queue you should switch off the automatic color map creation, since its OFF state assure that the analysis phase is skipped and conversion is run directly without prompting).
Note: due to a font-error with input fields in the color map editor you must have XP themes enabled, i.e. the classic Windows 2000 interface still works, but will display text and numbers as WingDings (fixed with a patch coming soon).
Hope this helps.
Best regards / Med venlig hilsen
Jacob Schäffer | Chief Developer
Grafikhuset
Paradis Allé 22, Ramløse
DK-3200 Helsinge, Denmark
Phone: [phone]
Email: [email protected]
Web: www.grafikhuset.net