Blurry pixels

[yeohray]

Yes, it is a bitmap.

This is the image when imported by Illustrator from a PDF/X file generated by Xara Designer:



Note that 2 blurry areas as highlighted by the red ovals.

When the brown frame is moved upwards, the underlying green bitmap shows through, and is sharper than the green background that's part of the brown frame:



Do you know why this is so? Why is the background not blurry, but the background that's part of the frame object is blurry? This is obvious even when viewed in Acrobat Reader, or Foxit Reader.

This is the frame object when viewed on a white background.



As to why we are making the changes ourselves, it's because we only want to change the prices on this design, which is a menu. Should it be this difficult?

Thanks in advance.