PDF print and Photoshop imported documents with transparency background

[Curieux75]

Hello, in Illustrator I need to import psd files with tranparent background, then I incorporate them and export the whole document in PDF with high print quality.
All psd documents are in 300dpi, CMYK, print quality.

It seems perfect with Adobe Reader DC *but* when I print the PDF document, I see the limits of the psd transparent layer. Its very soft, some time it doesnt change anything, sometime it bolds the vectorized text, change softly a color, depends of the printer.
I have tried to flatten the transparency and export in PDF/X but it doesnt improve the result.
Could you please help me ?

Thanks

[Monika Gause · Accepted solution]

Please read about the Yucky discolored box here:https://indesignsecrets.com/eliminating-ydb-yucky-discolored-box-syndrome.php

[Curieux75]

Thanks a lot Monika, I'll test that, have a nice day !