How can I preserve RGB color within Adobe PDF?

Question

I'm using Acrobat Pro 9.3.1, OS 10.6, and I'm creating PDF output from Keynote, strictly for on-screen viewing.  I would like to use Acrobat Pro to create a compact PDF file with screen-resolution graphics, however I keep running into problems with color changes applied by Acrobat.
The document contains bright RGB colors.  It also contains images, some of which are high DPI resolution. 
* If I use the OS X "Save As PDF..." feature, the generated file is about 32 MB.  Opening the resulting file with Preview, the file looks fine.  Opening the resulting file with Acrobat, though, shows the bright colors in the file as very drab-- almost as though it's been compressed into CMYK space.    Once it's in Acrobat, I can use the PDF Optimizer and save it as a mostly-adequate 10 MB file, but the color issue is annoying.
* If I use the "Save as Adobe PDF" feature, and save the file with "standard" settings, the resulting PDF file is 27 MB.  If opened in Acrobat, it shows the same CYMK-like color compression, and if opened in Preview, it shows the bright colors.
* If I use the "Save as Adobe PDF" feature, and save the file with "PDF/A-1b:2005 (RGB)" settings, the resulting PDF file is 50 MB. In both Acrobat and Preview, it shows up with full and correct colors. So obviously Acrobat is capable of handling RGB after all.  But this format is not really compatible-- it throws a warning about viewing in that format, and has all kinds of graphical glitches.  And, the file is even larger than I started with.
So, what I would like to know is this: How can I set up acrobat to let me produce those nice 10 MB files, without showing the funny color compression?

Answer 1

p taz wrote:
Ummm... not quite sure where you get that from, colour managed means converted as per settings in the device or application.  Acrobat preset for PDFX/1a specs a conversion to cmyk.  Other presets include RGB or unconverted and these are chosen by the app or user.
This is where your problem is, something inside Keynote is applying a conversion.  I was just eliminating the obvious, not just for you but for other, less knowledgeable readers.
Preview will use the monitor or sRGB profile and the only way to make sRGB or equivalents look flat is to feed it an untagged file that belonged to a very different gamut.
3. Yes, conversion is happening.  That's what I'm trying to prevent.
By definition, not converting means UNmanaged..  what you were calling unmanaged before is actually MISmanaged.
As mentioned, Acrobat, to my knowledge does not convert without being told to.  That instruction comes from the built-in actions of the application in question or a user choice and you may not be able to address the former.  If the former was the case then you might be able to work around by preparing your original file in a small gamut like sRGB and then it doesn't matter what Acrobat does unless you chose an unsuitable conversion at the user level.
> Acrobat preset for PDFX/1a specs a conversion to cmyk.
Okay.  That confirms what's going on.  Is there a way to turn this setting off, open the file, and then save it?
>This is where your problem is, something inside Keynote is applying a conversion.
No, actually keynote is irrelevant.  You can blame it and its color mismanagement all day, but the fact is that the change happens when it's opened in Acrobat with the default settings.  We know this because PS or PDF generated by keynote shows up okay in Preview or in that RGB PDF generated by distiller.  It's absolutely unambiguous.  I know that Acrobat is capable of converting the file without converting the color because it can make that RGB PDF.  I know that my monitor isn't totally whacked because if I view that same "RGB PDF" on a different machine and/or OS, it look fine there too.   But what I want to know is how to create that "RGB PDF" without the crazy bloat and iffy file format.  There must be some settings that can be applied in Distiller to get this done. 
From the suggestions that have been made here, it sounds like not many people have actually used recent versions of Acrobat Pro or Distiller on the Mac. (Options like "Email Files" and "PDFX4 2008" aren't there, converting PS files appears to broken, print to PDF is broken....)  That's okay, I don't expect you to know everything about this.  But, telling me just to not use the color blue or that my other programs are to blame isn't exactly helpful either.  Am I asking the questions in the right place? Is there some Adobe tech support venue that's more appropriate?