Color management frustration

[bluskool]

I am either missing something here or Adobe color management fails.

I get different color in Acrobat 8 than I do in any other CS3 app. For example, if I take a PDF that I am sure has no icc profile associated with it and open it in PS, Illy and Acrobat, I get the same color in PS and Illy, but a slightly different color in Acrobat. If there is no profile, shouldn't every program assume the profile is the cmyk profile that I have chosen in my CS3 color settings and render the same color?

P.S. CS3 color settings are set to honor profiles and are synchronized.
Also, please don't post if your only comment is going to be "PDF's should not be opened in PS or Illy." We all already know this to be part of the official Adobe party platform, but irregardless of this, shouldn't color be rendered the same since all the apps are using ACE?

 

[leonardr]

Re: Color management frustration

There are a variety of things that can be going on...

First and foremost - consider the simple handling of opening PDFs in each application:
* When you view a PDF in Acrobat - it is rendering EACH OBJECT'S color NATIVELY into the "destination color space" (either RGB or CMYK, depending - more on this later).

* When you open a PDF in Illustrator, the objects are CONVERTED to a single color space up front (since Illustrator only supports a single color model) and then rendered to RGB (for screen)

* When you open a PDF in Photoshop, it is RASTERIZED into a single colorspace of your choosing at the time of open.

Therefore, Acrobat is the ONLY one of the three applications to handle the object data natively and NOT convert it to something else.

Second, Acrobat's color settings may NOT be synchronized with the rest of the suite. Go to Acrobat's preferences, Color Management, and see if they are sync'd or not. You may not be using the colors you think!

Finally, Acrobat offers two different "modes" for rendering a page - with or without "overprint preview" enabled. Certainly, if your document contains any spot colors or uses OP operators - you want the screen-based view to appear just as the printer will output it. When this is enabled, it forces Acrobat to render FIRST into a "CMYK buffer" and then convert that entire buffer to RGB for the screen instead of just going "direct to RGB". This should explain to folks why this mode is slower to render, but produces more accurate results for print output.

So I don't know which of the above (or some combination thereof) is going on with your machine - but I hope that the information here is useful in helping you diagnose the problem. I also hope that it explains one reason why Adobe's policy is NOT to open PDFs in other apps for viewing...because what you see in other other apps is NOT accurate PDF rendering according to the standard.

Leonard Rosenthol
PDF Standards Evangelist
Adobe Systems

 

[bluskool]

Re: Color management frustration

Thanks Leonard,

That is how I understood Acrobat to handle rendering as well, but one of the first things that I do to a PDF is drop it on my preflight droplet which converts spot and RGB to cmyk and removes profiles (I hope it does anyway. The action I use says remove output intent which I assume means strip the icc profiles.)
Since the apps have to render color in some way, they should all render with their own default profiles (which are all SNAP in my case{I checked Acrobat though just to make sure and it was in sync with the rest of the suite}).

But here is the rub. I had to restart earlier and when I reopened the PDF that I was looking at in all 3 programs, the colors matched. The PDF was the same. I did not modify it or save it in any of the apps, so I have no explanation for why the rendering is correct now.

So whatever the problem was, it seems to have vanished with the restart.

Thank you for the thorough response Leonard. I do understand Adobe's policy on PDF's and I do try everything I can in Acrobat before resorting to Illustrator or, If the situation is really desperate, a rasterization in Photoshop.
Acrobat does have some nice options to fix up PDF's now and I rarely need to resort to anything else, but I would say the biggest reason I need to use another program is for converting build blacks to solids. Maybe in Acrobat 9 we'll get some color sliders : • ]

 

[prepression]

Re: Color management frustration

Try this source if you're looking for a good reference on color management:

http://www.amazon.com/Understanding...=sr_1_5?ie=UTF8&s=books&qid=1207459924&sr=1-5

Good luck!

 

[rich apollo]

Re: Color management frustration

The output intent is different than embedded profiles. I haven't found a way to strip the profiles out other than with PitStop. I don't know how to automate PitStop without investing in PitStop server.

rich

 

[bluskool]

Re: Color management frustration

Rich,

I think I have it figured out. I believe if you use the convert colors action and choose "de-calibrate cmyk" that that will get rid of the profile. I had my droplet doing that and removing output intent, but I guess the output intent part is not necessary.

Dan R.

 

[rich apollo]

Re: Color management frustration

Hmmm. Good idea. I'll have to test that one.

rich