Found Vector Objects in scanned jpg/PDF file. Why?

Question

Hi,

I'm using Acrobat DC. And I was checking a PDF file using Preflight. (It's a PDF file but consists of 5 large jpeg - just scanned in.)

Then to my puzzlement, Preflight found several vector objects in this PDF. And as I checked them, it does look like they are tiny vector objects created by Illustrator or InDesign (rectangles).

But this PDF is supposedly 'fresh' off from the scanner. 5 pages document was scanned in - resulting in 5 jpeg file, and that was saved as PDF for sharing.

So where do these Vector Objects come from? Did Acrobat DC created them as it opened and rendered the PDF?

Or Acrobat DC will never do that?

I am just completely puzzled about where these vector objects came from. If Acrobat DC never do such thing on its own - then we have to start to think about the possibility that the file might got replaced or edited by someone in the process.

Anyway, so confused. Any help/advice will be appreciated. Thanks.

Dov Isaacs · Accepted Answer

Very strange!

No version of Acrobat does or ever did convert any raster imagery in a PDF file to vector objects. And conversion to text only occurs if you run OCR on raster images (and that would not produce vector objects).

You didn't say how the PDF file was created. Was it created within Acrobat via the scan function? Or did your scanner create a PDF file and you subsequently opened that PDF file in Acrobat? There are some scanners that do attempt to do sophisticated object recognition as part of their scan and PDF creation process — that may be what is going on here.

- Dov

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