Generating a product pdf from the front end (enabled by ticking the box at Configuration>Shopfront>block 2 "Show pdf)
fails when an entry is present in the "Availability" field (field 5) on the page:
Products>Product Status
The error that streams onto the page is pasted below and the text appearing after the final "/" is the text that has been entered into the "Availability" field:
TCPDF ERROR: [Image] Unable to get the size of the image: http://sitename.com/components/com_virtuemart/assets/images/availability/text that has been entered into field 5
I have tested the bug on multiple websites - all running Virtuemart 3.0.6.4 and Joomla 3.4.1 Stable.
Changing the template to Beez for testing did not eliminate the issue.
When the text that has been entered into the "Availability" field is removed the pdf will generate properly.
In other words - you cannot make an entry into the Availability field AND generate a product pdf.