Black lines appear around objects when printing

When I print from CorelDraw fine black horizontal or vertical lines appear around some objects. So far, I have only observed it with objects which are either vector objects with a transparency or bitmaps with or without transparency, but not all such objects on a page are affected. The lines do not follow the original object border, but roughly a rectangle around the object. Lines are not solid, but irregularily interrupted.

When the same drawing is printed multiple times, the lines are exactly the same.

The lines do not show when the drawing is converted to PDF and then printed.

Printer is a Canon MX870. I have updated printer drivers but that had no effect. Operating system is Win 10 64-bit. No other applications show similar problems.

See attached scan for an example. All the circles are circle shapes with either texture or solid fill, some with transparency. The background is a solid fill. The three horizontal rows of circles are all identical copies of the same (bottom) row.

 

  • Ensure the option to print as bitmap is "unchecked"
  • Object hinting did not save the problem, but checking "Print as bitmap" did the job.

    Thank you all for your help.

    • Transparencies are always tricky (maybe texture fills too, I don't know) so converting to bitmap before printing, one way or the other, is usually a good idea.

      When sending via PSF the transparencies may have been converted to bitmaps, depending on export settings.
      • Thank you. So far printing as bitmap seems to work fine, but if mysterious lines reappear, I'll try converting to bitmap.

        Just out of curiosity:

        Because of your remark, I've imported the PDF back in CorelDraw. Objects with textures had been converted to bitmaps, but the transparencies of solid fill objects are still there. And this file now prints ok even from CorelDraw. So maybe the problem has to do with textures...
        • Possible.
          Depending on PDF compatibility level, certain things may be supported or not.
          When not, Draw has to find a way around it, and it often is by converting tricky parts to bitmaps.

          For fun, try Publishing the original document to PDF using highest compatibility level, then import back to see if there's any difference.