|The following two examples will further prove my theory that Acrobat "Assumes" its default Working Profile for Untagged elements within a PDF.
I really like using ProPhoto and Whacked RGB images in my color-management tutorials because they are so obvious when the wrong profile is Assigned or Assumed or ignored or improperly Converted.
Set Acrobat Working RGB to "ProPhoto RGB" go to Acrobat> Preferences> Color Management for this screenshot and make the change (then Quit Acrobat and reopen my original PDF):
You should now see huge color changes in the right column below Acrobat is no longer Assuming sRGB on Untagged images because you changed its Working RGB to ProPhotoRGB however notice that the Untagged ProPhotoRGB now "matches" the Tagged set!
This is because Acrobat is making the correct Assumption, its default Working RGB is ProPhoto in this example).
SEE AN EVEN MORE BIZARRE EXAMPLE
Set Acrobat Working RGB to "Whacked RGB" (you will have to have that ICC profile installed to select it) or take my word for it that my screen shots are good:
Then Quit Acrobat and reopen my original PDF you should see this:
Notice only the Untagged Whacked RGB is displaying proper like the Tagged set because I changed Acrobat Working RGB to Whacked RGB in my Acrobat preferences (see above screenshot).
AGAIN: This is happening because Acrobat "Assumes" (Assigns) its default working profile to Untagged elements. This is an extremely important concept to understand if you need to visually PROOF a PDF on the monitor, and/or if you need to Convert colors in a PDF to a Print or Destination space because if Acrobat uses or Assumes the wrong Souce profile all color Conversions will be off, including Source> Monitor, Source> Destination, and Source> Print Space.
The point I am exhausting here is unless you are embedding profiles in Acrobat PDF and using those profiles to Convert to Monitor RGB, Print Profiles, and Destination spaces you are either ruining colors on a daily basis, or you are getting lucky that the Source profiles are the same or close enough to your default working spaces that you don't have to figure out what's happening.
CLASSIC BROKEN WORK FLOWS in the Real World:
The classic example of profile problems in the real world is the old-school print shop's clueless "color expert" who ignores our embedded profiles, because he says, he has "turned color management off" and "doesn't use profiles."
He tells us our color is "bad" because his print is bad, and he will try to "fix" our bad color and print another round of proofs.
Does this sound familiar?
What the cave man actually did was strip our document of its embedded profile(s) he ignorantly Assumed-Assigned his own default profile(s) then he takes a sledgehammer and starts beating up our color into his broken workflow....
ANOTHER CLASSIC MISTAKE WITH PDF:
Some moron downstream drags my .pdf into Photoshop and rasters all my vector logos and type into pixels and saves it as a .tif (or worse a .jpg) ... this just happened to me (again) last month after a pointed conversation about printing my Illustrator vector .pdf through a RIP and maintaining vector sharpness in the print (of course my logos and text printed like crap...).