This has happened during a few different projects I've had:
I'm just trying to make sure that the colored box prints the exact same color as the PDF's color and it's not.
Say I'm given a PDF, it's a poster, and it needs to have bleed (a border around it) added.
I'll open Illustrator, put the PDF in there, and use a colored box for the additional bleed/border I'm adding.
I'll use the eye dropper, click on part of the PDF - it'll give me the color of that spot.
I'll take that color and apply it to the colored box, it changes color.
The issue is that sometimes, that color the eye dropper picks up doesn't actually match the PDF's true color.
I can fill in the colored box with whatever color the eye dropper picks up, but it's often a weird color, like with CMYK number values being at 98.35% or something
And even when the color value on the PDF and box are the same, you can see a slight difference between that colored box and the real PDF.
I'll even export that to a PDF and make sure it's correct, using the Object Data Tool or whatever it is, and then using the eye dropper there, and seeing that the color for my box and the PDF are at the same CMYK color values. And you can still see it's incorrect very slightly, and then when you print it it's obviously not the same. Even when I try picking it up in HSB or RGB, it's no good.
So I don't know what to do. This has happened a few times and someone helped me fix it the first time, I think, but now I'm on my own and don't know how to correct it.
Thanks for any help.
[ Moved to the Illustrator forum as your workflow is primarily in there ]
Although Illustrator can 'place' a PDF, it has a somewhat limited range of support for color management in placed assets (output intents and blend spaces in the PDF, etc.) If you open the PDF instead of placing it, you can access the page elements natively and either resize them into the bleed zone or add new ones with the same swatch.