Print-ready pdfs - shadows around linked .psd files

[prepress labels]

Hello!

We are having the occasional issue with our print-ready .pdf files (that we generate out of Illustrator). Whenever the .ai file contains a linked .psd, we end up with a small grayish CMYK "shadow" where the .psd art ends and the vector art begins (in the .pdf only):



We can't figure out how to get rid of this in the Illustrator .pdf job options.

If we save the linked .psd file as a .tif, then the problem goes away.




It's not simply a matter of zooming in and out on the .pdf--this is showing up on our plates when we output the files.
We'd like to avoid having to resave all our thousands of .psd links and relink them all in our Illustrator files--has anyone else experienced this issue?

Thanks for any feedback!

 

[Greg_Firestone]

Hi Prepress Labels,

Can you please provide what version of Adobe Illustrator you are using?

Also, can you provide details regarding your output settings? One of the standard output profiles? Or is it a modified one?

This info could be useful in helping solve your issues.

Greg

 

[prepress labels]

Illustrator CS 5.1
We're using a custom .pdf preset--here's a screenshot of the compression section:



Let me know if this helps.

 

[Greg_Firestone]

Hi Prepress Labels,

There are a couple settings specified in that screenshot: downsampling and compression.

To test each setting individually, try outputting a file with

a) no downsampling and your current compression settings
b) your current downsampling settings and no compression

Greg

 

[Joe Duffy]

Hi Prepress Labels,

There are a couple settings specified in that screenshot: downsampling and compression.

To test each setting individually, try outputting a file with

a) no downsampling and your current compression settings
b) your current downsampling settings and no compression

Greg

But the tiff file placed works, just not the psd file so if he uses the same .pdf settings for both how could this be the cause?

 

[Greg_Firestone]

But the tiff file placed works, just not the psd file so if he uses the same .pdf settings for both how could this be the cause?

Hi Joe,

I'm assuming the problem only occurs during PDF export (i.e. they look fine when placed). I don't think it's a bad idea to test compression and downsampling settings because they are options in the PDF export and effect raster data. Ideally the PSD and TIFF behave same when placed and exported but in this case they are not. If you downsample or apply compressions, you're modifying the images. This test will allow us to rule out these variables.

I'm also curious how the psd/tiff files are built. The tiff file would most likely have a clipping path (unless it's a layered TIFF). The PSD could have layers with a layer mask. This can play a role as well. For example, some apps won't downsample images that have a clipping mask in order to prevent a glow around the edges from downsampling.

Greg

 

[curveto]

The provided images look like a) the trap engine is active and b) it is finding an edge that you don't want or don't believe exists (but does).

Walk that way and see what you find...

 

[prepress labels]

The provided images look like a) the trap engine is active and b) it is finding an edge that you don't want or don't believe exists (but does).

Walk that way and see what you find...

The .pdf file hasn't been run through a trapping workflow yet--this is happening when I save an .ai file as a .pdf. Is there a trapping engine native to Illustrator that I'm unaware of?

 

[curveto]

Illustrator had trapping support added more than a decade ago.

 

[brockp28]

Illustrator had trapping support added more than a decade ago.

Yes, but trapping is not done automatically when you export. AFAIK, trapping needs to be done through the pathfinder, or manually.

We have had similar thing to this happen as well when exporting from Illustrator, and changing compression and downsampling settings didn't do a thing unfortunately.

I highly doubt it's trapping, as you say, it hasn't been run through a trapping engine yet.

Our only work-around was to export the full Illustrator file as tiff, link into Indesign, and export normally from there.

It's a PITA, especially for multi-page docs, but we had no other way...

 

[Lukas Engqvist]

Looks like the alpha channel is down sampled differently than the image. Note that photoshop to PDF does not support blending modes, which can cause problems since what is left is the alpha channel to handle all transparency. This kind of issues could happen with OPI images, which is where I learned about how downsampling image and alpha is two separate processes, the alpha in a pixel is not hardwired to the pixel boundaries.