I received a pdf from a client containing several invoices. Upon further inspecting, some lines on the invoice seem digitally produced. When I tried selecting the page, copying it then pasting it on paint, the lines that seemed suspicious disappeared.

I should note that the source invoice paper are very thin. So before jumping to any conclusions, is it common that some printers or printing software compensate for blurry or lost lines and text and try to “enhance them”?

  • $\begingroup$ Are you sure that is what your seeing. Or rather that the line is just to thin that you would just miss the line entirely when rasterized. You should in general strive to avoid lines smaller than 1/4of a postscript point because thats close to a 300 dpi line. Which is allready hard thing for a 600 dpi printer to reproduce reliably as a uniform line any smaller than this is really going to tax your system. Anyway if you send it as vector then some drivers strive to make all vector lines some width. Byt if you send it as bitmap it can dissapear. $\endgroup$
    – joojaa
    Aug 19, 2020 at 9:33
  • $\begingroup$ Not sure you can draw any conclusions by pasting stuff in paint. $\endgroup$
    – joojaa
    Aug 19, 2020 at 9:35
  • $\begingroup$ @joojaa with lines I meant the invoice number, some letters and numbers, and with some invoices I was left with a blank background. I used paint just to try and see if the image was loaded on the pdf then edited using pdf tools. It seems like there is a background and lines drawn on top of it to compensate for lost data. I was just wondering if it were a known enhancement that some scanners do, or if these lines were manually added. $\endgroup$
    – obi
    Aug 19, 2020 at 11:47
  • $\begingroup$ Yeah scanners refuse to read items with omron rings. But cameras do not. Try photographing. $\endgroup$
    – joojaa
    Aug 19, 2020 at 11:53
  • $\begingroup$ That’s not exactly what I mean. I received scanned invoices from a client and I want to know if the client manually edited them or if the edit is just something scanners do to compensate for low quality. $\endgroup$
    – obi
    Aug 19, 2020 at 14:34


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