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I am using latest Adobe Reader XI and after appying signature and printing .PDF document, I get signature displayed inside white rectangle and it covers what should be not covered. It looks as if signature was merely copied and pasted like this:

enter image description here

You see it covers background text as well as line where signature should have been on. Why is that so? Why I can't see this before printing document?

Thanks

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How did you supply the graphical signature? Did you upload the signature as a file with an alpha (transparency) channel? (Tip, if you uploaded a jpg then the answer is no since jpg does not support transparency.)

If you did supply an alpha channel in your sig image, then the behavior is considered a feature of the way that Adobe adds the graphical representation of the digital signature to the document.

It is not a requirement of the digital signature standards that the (optional) graphical representation of the digital signature occlude the content beneath it. Adobe chooses to do it this way.

For example, when you digitally sign a PDF document with CoSign, and you include the graphical representation, the resulting PDF, as displayed by Adobe PDF Reader, looks like this:

Example of a PDF signed with CoSign

You can see from the screen shot (from Adobe PDF Reader) that transparency information was supplied by CoSign for the Signer Information portion of the signature block, but not for the Graphical Signature part. -- CoSign adds both the Signer Information and Graphical Signature to the PDF.

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  • Yes, the signature was in .JPG format that I supplied to Adobe Reader but the form was printed twice in different offices and first form came out properly while second had graphical signature occluding content. Any idea as to why? Can you tell me how to add Alpha Channel to signature in .JPG format?
    – Boris_yo
    Nov 16, 2014 at 7:49
  • Hi, it is impossible to add transparency information to a jpg, the jpg format doesn't support it. You will need to convert it to png or gif, which do. You can use the free gimp image editor.
    – Larry K
    Nov 16, 2014 at 10:35
  • Larry, do you mean that I just open .JPG file and save it as .PNG? It will remove white background from graphic or separate graphic from background with Alpha Channel?
    – Boris_yo
    Nov 16, 2014 at 11:10
  • you need to add the transparency information to the image, then save it as a png. See this question.
    – Larry K
    Nov 16, 2014 at 11:23
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    Note that we don't know if Adobe will use the transparency information when it adds the image to the pdf. You will need to try that (and let us know how it worked!)
    – Larry K
    Nov 16, 2014 at 11:24

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