The same PDF file is shown differently in iPad and Mac

Question

I bought a PDF book from O'Reilly, and copied the file to iPad to read.

And it I see some marks as below. I tested with a couple of PDF apps and all of my apps show the marks.

And this is the screen capture to open with Preview.app in Mac which doesn't have the mark.

• Why is this? Does the Preview.app or Acrobat cuts out the marks whereas the iPad apps don't (or can't)?
• Is that a bug in iPad app?
• Is there a PDF tool to remove those marks?
• Is there an iPad app that doesn't show the marks?

ADDED

I tested with some of my iPad pdf apps.

• iBook - OK
• PDFReader - shows the marks
• iAnnotate - shows the marks
• Note Taker HD - shows the marks

I think some (or most) of the iPad pdf readers doesn't process the marks correctly.

Answer 1

Why is this?

Those marks are called Printer marks or Crop marks. They are used for professional document production such as printing books.

Does the Preview.app or Acrobat cuts out the marks whereas the iPad apps don't (or can't)?

It seems as if Preview.app and Acrobat intelligently ignore printer marks, whereas other apps do not.

Is that a bug in iPad app?

I do not think it is a bug.

Is there a PDF tool to remove those marks?

There is a question about this on stackoverlow, but in short, cropping the document will get rid of the marks.

Is there an iPad app that doesn't show the marks?

I don't know of any than can automatically hide crop marks, but advanced pdf reading apps for iPad such as Goodreader allow you to crop the pdf on the fly.