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I want to know that if I print this noise texture with high-quality printer and I take a photocopy of that print, will the quality remain same? And how can I match or compare the quality of the print with original image file?

I want to use this image as an identifier. So I just want to know whether it is copy-proof or not. So if someone is having the printed hardcopy and not the original file, can he make an exact copy of that?

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    Hi. Welcome to GDSE. Why do you need to print something, then photocopy it? Why could you not just print more copies? Or if you need to share the image, you could just send someone the image file. Also what kind of photocopying are you referring to? Are you talking about traditional Xerox photocopying which was usually quite bad quality, or modern all-in-one printers which scan digitally then print. – Billy Kerr Apr 29 '19 at 17:01
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    It is very likely that it wont even reproduce accurately. Addressing individual printer dots is, how shall we say, tricky. Mainly because your average printer user does not want to deal with individual dots addressing. So even just getting the image hit the grid perfectly is not easy. Lots of moire. – joojaa Apr 29 '19 at 18:25
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    A copy of a print will not result in the exact same digital file. So the answer is no, but whether you will be able to detect a copy is a different question.. Stan has already answered, so there's no point in repeating it. Also this isn't really a question about graphic design, and very close to being off-topic. – Billy Kerr Apr 29 '19 at 19:32
  • Sure. You can use dimensional differences between original and copy (use moiré to detect difference) or the density differences overall or microdensitometric reading. You can compare the derivatives of the images using fast Fourier transforms. You can compare hue as no two colourants appear the same on the same strata. You can use mechanical manipulation of the copies (some colourants do not bond the same way to the strata.) You could even make a waveplate or hologram of each and compare their optical effects. In short, unless copies are compared to each other, there will be some difference. – Stan Apr 30 '19 at 13:15
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No, it will not, which explains the intrinsic value of the "original" of most anything. An attempt to copy an original in every detail has a variable degree of social acceptance. To some 'faithful' reproduction is highly desirable while 'counterfeit' has lower acceptability.

The operative term here is copied "exactly."
No copy is the same as the "original."

That is the essence of the ability to diagnose or evaluate the fidelity of the copy (and related processes) to the original.

Quantitatively comparing the two is not so simple. The answer lies in the preparation of the original. Make an original that makes what you want to copy difficult. If you want to measure acutance, use fine lines. If you want to measure density, use greyscale, etc. If you want to make an original that is difficult to reproduce you must use unconventional materials, processes, and configurations. Investigate steganography or the embedding of information into seemingly random patterns.

Your question might be beyond the scope of of the graphic design stackexchange site.

Qualitatively, the practical answer is that if you cannot detect a difference, the two can be considered the same.

By the way, "One experiment is worth a thousand expert opinions." - Bill Nye, the science guy.

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  • Your answer is satisfactory. But can you suggest me the way to compare the original and duplicate? So I can just get started on my research. Thank you. – Rahul Savsani Apr 30 '19 at 6:26
  • @RahulSavsani Please understand that a print of a digital file is a copy. The digital file is the original. Your original must be in final form, not one that must be created for final reproduction which is subject to errors in its creation. This is the subtle but important point you must solve. Another detail is the gradual degradation (change) of the original which will affect the accuracy of your "identifier." – Stan Apr 30 '19 at 13:26
  • Thanks for the answer again. And yes, I just want to know that how can I measure the gradual degradation of the original which occurs on any attempt to reproduce the original print? So that I can distinguish between original print and a reproduced print. – Rahul Savsani Apr 30 '19 at 13:46
  • Can I use steganography here to measure degradation in quality due to sequential printing, so that I can distinguish between original and a reproduced print? – Rahul Savsani May 8 '19 at 12:38
  • @RahulSavsani I don't know how stable the message remains through duplication. Possibly image degradation will lose the "internal message" making the process an indication of tampering/unwarranted duplication. – Stan May 8 '19 at 14:19

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