<p>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.</p>
<p>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”?</p>

CC BY-SA 4.0
2020-08-19T09:33:19.923Z
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.
joojaa
CC BY-SA 4.0
2020-08-19T09:35:20.687Z
Not sure you can draw any conclusions by pasting stuff in paint.
joojaa
CC BY-SA 4.0
2020-08-19T11:47:57.750Z
@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.
obi
CC BY-SA 4.0
2020-08-19T11:53:29.297Z
Yeah scanners refuse to read items with omron rings. But cameras do not. Try photographing.
joojaa
CC BY-SA 4.0
2020-08-19T14:34:51.807Z
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.
obi
CC BY-SA 4.0
2020-08-19T14:50:33.737Z
Sounds like drawing errors of teh PDF viewer
joojaa
CC BY-SA 4.0
2020-08-20T08:06:26.473Z
I think if you should consult a professional expert on this matter if the outcome has any legal effects. Without having access to the "data" in question we can just guess and even if we had, I wouldn't draw any conclusions because of an answer from somebody on the internet where I don't know if he is really an expert on the subject.
wychmaster
CC BY-SA 4.0
2020-08-20T21:20:31.067Z
Thank you for that advice. That’s what I was planning to do. But to seek an expert I need to present the case to the higher ups for approval, and I just wanted to check if this was a known behavior of scanners to consider and report on.
obi
CC BY-SA 4.0
2024-07-27T14:38:06.227Z
See also http://www.dkriesel.com/en/blog/2013/0802_xerox-workcentres_are_switching_written_numbers_when_scanning
lhf
<image-processing><pdf>
Do scanners and scanning software compensate and enhance blurry sources?
obi
# Do scanners and scanning software compensate and enhance blurry sources?

(Asked by: username_0 on 2020-08-19)

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”?

**Tags:** image-processing, pdf

> **Comments:**
> **username_1**: 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.  
> **username_1**: Not sure you can draw any conclusions by pasting stuff in paint.  
> **username_0**: @username_1 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.  
> **username_1**: Yeah scanners refuse to read items with omron rings. But cameras do not. Try photographing.  
> **username_0**: 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.  
> **username_1**: Sounds like drawing errors of teh PDF viewer  
> **username_2**: I think if you should consult a professional expert on this matter if the outcome has any legal effects. Without having access to the "data" in question we can just guess and even if we had, I wouldn't draw any conclusions because of an answer from somebody on the internet where I don't know if he is really an expert on the subject.  
> **username_0**: Thank you for that advice. That’s what I was planning to do. But to seek an expert I need to present the case to the higher ups for approval, and I just wanted to check if this was a known behavior of scanners to consider and report on.  
> **username_3**: See also http://www.dkriesel.com/en/blog/2013/0802_xerox-workcentres_are_switching_written_numbers_when_scanning  

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## 0 answers

