Mark Stephens Mark has been working with Java and PDF since 1999 and is a big NetBeans fan. He enjoys speaking at conferences. He has an MA in Medieval History and a passion for reading.

Interesting PDF bugs – ‘Phantom’ PDF objects

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I have been looking at some Annotation issues and came across an interesting feature in a sample PDF file. I viewed it in Acrobat’s viewer and saw the following.

PDF object view

It is a freetext annotation with an AP object to define how it appears. It was not appearing in our PDF viewer so I dug down and found we were not reading the AP object (number 22). Then I opened up the raw PDF file to see why, which is where it gets very interesting…

Actual PDF data

The PDF only contains 21 objects and there is no AP object attached to the Annotation. The object that I am seeing in Adobe Acrobat is actually a ‘synthetic’ object created by Adobe – it does not exist in the file. So does it really exist?

This post is part of our “Understanding the PDF File Format” series. In each article, we discuss a PDF feature, bug, gotcha or tip. If you wish to learn more about PDF, we have 13 years worth of PDF knowledge and tips, so click here to visit our series index!



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Mark Stephens Mark has been working with Java and PDF since 1999 and is a big NetBeans fan. He enjoys speaking at conferences. He has an MA in Medieval History and a passion for reading.

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