Help with making watermark that appears when photocopied or scanned

[Guest]

I need to create a textured background on a coupon.  Hidden in this background is the word VOID.  The word void won’t be very noticeable when you’re looking at a original coupon.  But if it’s photo copied or scanned, the word will appear. I will need to print the coupon on a monochrome laser printer.  I believe this can be accomplished with illustrator.  Has anyone done this?  Please help.  Thanks

[Jacob Bugge]

LaserTest,

In order to be only become distinguishable when scanned/photocopied, the word has to have a shade that becomes darker and sharper in that process.

Unfortunately, newer scanners photocopiers have options like (best) photo with rather convincing reproduction, quite different from older ones, so I am afraid it is impossible/very difficult.

When you say monochrome, I presume you mean black (greyscale (or grayscale, especially over there)) only. If you could use another dark colour, especially one difficult to reproduce accurately, that might be a solution.

[_scott_]

Simply put... you can't on a monochrome laser printer.

Special inks are used to add privacy features. You can't load special inks in a laser printer.

[Mylenium]

What the others said - the whole idea won't work for a million reasons. Your own printing process alone can't deliver the goods here, as you are already introducing a raster that may make any hidden text more prominent - there is no way for even the best laser printer to print such soft greyscales without special toners/ inks. If this really is important, you will need to talk to a proper print shop who can do this with special UV/ infrared/ hi reflex inks, varnishes and ideally as a non-offset flexo process to retain contiguous features and edges....

Mylenium

[Guest]

WOW… Thanks for the quick response but don’t you think your throwing in the towel a little too easily.  I’m not saying that this is common and I will agree that newer scanners can produce a higher resolution which can defeat a low level watermark of this type.  I also agree that a truly anti-photocopy watermark will need to be produced by a printing company, not a desktop laser printer.  But to say Impossible I must disagree.  Somehow this person has done it.

http://www.troygroup.com/industry/healthcare/products/printer/securerxprinter.aspx

[Mike_Gondek]

I believe that is built into the paper - probably some sort of chemical reaction that occurs when the paper is heated during the copy process. You could design the logo in Adobe CS, and have a printer add that into the paper.

Do a search for security paper printing to find more places, but here is one

http://www.protectedpaper.com/

[Mylenium]

I didn't say it was impossible at all, it's just impossible with an off-the-shelf laser printer. Whatever method they use (thermal paper, a second (non-rastering) transfer drum adding a special pattern using a special toner, special varnish/ sealnat oil etc.) they do on customized hardware and no doubt they let people pay extra for such a certified machine and the supplies. I really think you are looking for too easy an solution that simply doesn't exist. All of my experience with security printing revolves around using special inks, special papers, varnishes, hot stamping, holograms, laser cut micro patterns and preferrably non-offset printing processes and I know that such facilities are usually very protective about their secrets and won't give them away so anyone can do it on his home printer... So for what it's worth, you might find more peace when doing this conventionally and having your local printer apply some invisible coating that only shows up under very bright light to invalidate photocopying on blank paper stock and you only print the pertinent voucher codes on top yourselves...

Mylenium

[Guest]

First I would like to thank everyone for your replies.  I also want to emphasize that I’m in total agreement that a true, quality, security watermark can only be achieved by use of specialty inks, varnishes, and more.  Personally I view this as a very basic attempt at creating a security watermark.  Unfortunately for me my boss is hell bent on this. 

Good news though, and you all might find this interesting.  I just received two close-up images of this poor man’s security watermark.  The Master is the image that was printed on the monochrome laser printer and the Copy is the image that was produced by the copier after being photocopied. As you can see the copied image is not as crisp.  Hence the watermark is more apparent. The lower curved area is a piece of the font.  The rest is the textured background.  The font is filled with a 45 degree line pattern.  The background appears to be a halftone with a evenly spaced dot. 

So I guess I should revamp my question to ask;

1 How could I create a fill pattern for a font like this?

2 How would I create a similar background pattern?

Thanks in advance for your help.

[Guest]

Thanks everyone for your input.  I was messing around with this over the weekend and found the solution.  It was a LOT easier than I thought it would be.  In fact I came up with many different patterns that worked.  In short I created a background texture.  I then overlaid the background texture on the font and made it perpendicular to the back ground.  I also rasterized it about ¼ of the resolution.  If you look for the security word, you can see it.  But it’s difficult because the pattern kind of blurs your vision.  When copied, the copier interprets the angles differently and makes one more prominent than the other.  The important thing is to keep the opacity of the background texture and the font the same.  This lets your vision blur them together. 

Now for the million dollar question. OK, so I did what I was asked.  I hid a word in a background texture that became more noticeable when copied.  Is this really a security feature?  In my opinion NO, if it can be printed on your home laser printer than someone else can reproduce it.  That’s not secure.

[Jacob Bugge]

For my part you are welcome, LaserTest.

Is this really a security feature?  In my opinion NO,

I agree.

Besides, the difference you do see between the original and the copy may still depend on the equipment used; you would have to try it on a wide range of different equipment to be sure that it is consistent.

[aarkeys]

Hi Laser Test,

Could you share your image on which you tested.

It can be of great help to me.

thanks in advance