How to avoid copying/scanning printed paper ?

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Re: [SLE] Please Desperate Help to...

Franky Goethals

17 Feb 2005 17 Feb '05

21:51

Hi, I remember some years ago, when i published something under windhoze, that i didn't want to see copied or scanned, that i used a sort of watermark, to avoid this. Does anybody has any knowledge if this exists under Linux, or how to avoid this another way ? Printing on special paper is out of the scope, too expensive. Thanks in advance, Franky. -- _________________________________________________________ GOETHALS Franky Driegaaienstraat 104 B-9100 SINT-NIKLAAS B E L G I E Verantwoordelijke MVS Support voor Euroclear Bank Secretaris GSE Z/OS Systems Working Group Privaat doeleinden & GSE Workgroup : Tel. : 32 - (0)3 / 776.65.17 GSM : 32 - (0)473 / 98.90.24 Mail & MSN : franky.goethals@telenet.be http://gsezos.dyns.cx Professionele doeleinden : Tel. Werk : 32 - (0)2 / 224.15.92 Mail werk : goethals_franky@euroclear.com http://www.euroclear.com Registered linux user #378931 (counter.li.org) _________________________________________________________

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James Knott

17 Feb 17 Feb

23:09

New subject: [SLE] How to avoid copying/scanning printed paper ?

Franky Goethals wrote:

...

Hi,

I remember some years ago, when i published something under windhoze, that i didn't want to see copied or scanned, that i used a sort of watermark, to avoid this.

Does anybody has any knowledge if this exists under Linux, or how to avoid this another way ?

Printing on special paper is out of the scope, too expensive.

Thanks in advance, Franky.

Any decent word processor should support watermarks. OpenOffice Writer does.

Randall R Schulz

23:20

New subject: [SLE] How to avoid copying/scanning printed paper ?

Franky, On Thursday 17 February 2005 13:51, Franky Goethals wrote:

...

Hi,

I remember some years ago, when i published something under windhoze, that i didn't want to see copied or scanned, that i used a sort of watermark, to avoid this.

Does anybody has any knowledge if this exists under Linux, or how to avoid this another way ?

Could you say a little more about what you want to do. Do you just want a watermark on a paper document? What application(s) are you using to produce these documents? OpenOffice.org, for one, has built-in support for layering watermarks under each page.

...

Printing on special paper is out of the scope, too expensive.

Thanks in advance, Franky.

Randall Schulz

Franky Goethals

18 Feb 18 Feb

13:51

New subject: [SLE] How to avoid copying/scanning printed paper ?

Hi Randall, I just want to avoid that somebody can copy / scan my presentation that i will be giving, more not. If there exist other possibilities to do this... i'm open for other solutions. I've done this once by a sort of special watermark, but under windows. Is a normal watermark sufficent ? Kind regards, Franky. On Friday 18 February 2005 00:20, Randall R Schulz wrote:

...

Franky,

On Thursday 17 February 2005 13:51, Franky Goethals wrote:

...
Hi,

I remember some years ago, when i published something under windhoze, that i didn't want to see copied or scanned, that i used a sort of watermark, to avoid this.

Does anybody has any knowledge if this exists under Linux, or how to avoid this another way ?

Could you say a little more about what you want to do. Do you just want a watermark on a paper document? What application(s) are you using to produce these documents?

OpenOffice.org, for one, has built-in support for layering watermarks under each page.

...
Printing on special paper is out of the scope, too expensive.

Thanks in advance, Franky.

Randall Schulz

-- _________________________________________________________ GOETHALS Franky Driegaaienstraat 104 B-9100 SINT-NIKLAAS B E L G I E Verantwoordelijke MVS Support voor Euroclear Bank Secretaris GSE Z/OS Systems Working Group Privaat doeleinden & GSE Workgroup : Tel. : 32 - (0)3 / 776.65.17 GSM : 32 - (0)473 / 98.90.24 Mail & MSN : franky.goethals@telenet.be http://gsezos.dyns.cx Professionele doeleinden : Tel. Werk : 32 - (0)2 / 224.15.92 Mail werk : goethals_franky@euroclear.com http://www.euroclear.com Registered linux user #378931 (counter.li.org) _________________________________________________________

Randall R Schulz

15:00

New subject: [SLE] How to avoid copying/scanning printed paper ?

Franky, On Friday 18 February 2005 05:51, Franky Goethals wrote:

...

Hi Randall,

I just want to avoid that somebody can copy / scan my presentation that i will be giving, more not.

If there exist other possibilities to do this... i'm open for other solutions. I've done this once by a sort of special watermark, but under windows. Is a normal watermark sufficent ?

Ummm... Maybe. What do you mean by "special watermark" and "normal watermark?" As you may know, the real, original meaning of "watermark" refers to a density modulation in the fibers of a piece of paper itself. To see such a watermark you may have to hold the paper up to back lighting. As so often happens, the computer world has appropriated the term for a vaguely similar but distinct concept: A printed image, usually in an grayed-out form, that is printed on each page to indicate the document is "Confidential" or "Preliminary" or to include some kind of proprietary marking. The OpenOffice.org word processor allows you to specify an arbitrary graphic image to be used as the watermark for any given document. Start it up, open the on-line documentation and search for "watermark" and you'll see how to do it (hint: Select from the Format menu the Page... command and change the pop-up from "Color" to "Graphic"). The OOo graphic editor has commands that will take a fully saturated graphic and dim it for use as a watermark image. You should find that, too, when you search in the on-line documentation.

...

Kind regards, Franky.

Randall Schulz

Randall R Schulz

19 Feb 19 Feb

17:04

New subject: [SLE] How to avoid copying/scanning printed paper ?

Franky, On Friday 18 February 2005 05:51, Franky Goethals wrote:

...

Hi Randall,

I just want to avoid that somebody can copy / scan my presentation that i will be giving, more not.

If there exist other possibilities to do this... i'm open for other solutions. I've done this once by a sort of special watermark, but under windows. Is a normal watermark sufficent ?

Kind regards, Franky.

In looking into the PDFTK utility suggested as an answer to another poster's request for PDF concatentation tool, I discovered that it (PDFTK) is capable of adding watermarks to existing PDF files. So this may be another option for you. PDFTK: http://www.accesspdf.com/pdftk/ Randall Schulz

Franky Goethals

17:31

New subject: [SLE] How to avoid copying/scanning printed paper ?

Hi Randall, Thanks for this supplemental info. Do you think an ordinary watermark will avoid copying/scanning my documents ? The aim is to protect my work, that noone can copy it without my permission. Greets, Franky. On Saturday 19 February 2005 18:04, Randall R Schulz wrote:

...

Franky,

On Friday 18 February 2005 05:51, Franky Goethals wrote:

...
Hi Randall,

I just want to avoid that somebody can copy / scan my presentation that i will be giving, more not.

If there exist other possibilities to do this... i'm open for other solutions. I've done this once by a sort of special watermark, but under windows. Is a normal watermark sufficent ?

Kind regards, Franky.

In looking into the PDFTK utility suggested as an answer to another poster's request for PDF concatentation tool, I discovered that it (PDFTK) is capable of adding watermarks to existing PDF files.

So this may be another option for you.

PDFTK: http://www.accesspdf.com/pdftk/

Randall Schulz

Randall R Schulz

17:43

New subject: [SLE] How to avoid copying/scanning printed paper ?

Franky, On Saturday 19 February 2005 09:31, Franky Goethals wrote:

...

Hi Randall,

Thanks for this supplemental info.

Do you think an ordinary watermark will avoid copying/scanning my documents ? The aim is to protect my work, that noone can copy it without my permission.

Greets, Franky.

Well, it (*) certainly will impede causal attempts to copy the work. The specifics depend on the watermark you choose, the resolution of the printer on which the document is printed, the resolution of the halftone screen with which the watermark is rendered, etc. You should experiment with these parameters (and some real photocopiers) to see what gives the best results. (*) I still don't know what you mean by an "ordinary" watermark or what varieties of watermarks you know of. As I mentioned earlier, the original meaning of watermark is a mark embedded in the paper itself, not part of the image printed upon it, as is the meaning of the term as appropriated by the computer industry. Randall Schulz

Carlos E. R.

22:01

New subject: [SLE] How to avoid copying/scanning printed paper ?

The Saturday 2005-02-19 at 09:43 -0800, Randall R Schulz wrote:

...

(*) I still don't know what you mean by an "ordinary" watermark or what varieties of watermarks you know of. As I mentioned earlier, the original meaning of watermark is a mark embedded in the paper itself, not part of the image printed upon it, as is the meaning of the term as appropriated by the computer industry.

It must be a special watermark designed to interfere with the scanner matrix. The document can be scanned, but the quality is bad, and OCR does not work. The design is most probably proprietary. There are also some special fonts designed so that the human eye can read it, but they can't be read by scanning the radio waves emitted by the CRT monitor - believe me, there are businesses very paranoid about such things. For example, PGP for windows support it: Secure Viewer. Select this option to protect the data from TEMPEST attacks upon decryption. If you select this option, the decrypted data is displayed in a special TEMPEST attack prevention font that is unreadable to radiation capturing equipment, and cannot be saved in decrypted format. For more information about TEMPEST attacks, see the section on vulnerabilities in An Introduction to Cryptography. -- Cheers, Carlos Robinson

Randall R Schulz

20 Feb 20 Feb

02:11

New subject: [SLE] How to avoid copying/scanning printed paper ?

Carlos, On Saturday 19 February 2005 14:01, Carlos E. R. wrote:

...

The Saturday 2005-02-19 at 09:43 -0800, Randall R Schulz wrote:

...
(*) I still don't know what you mean by an "ordinary" watermark or what varieties of watermarks you know of. As I mentioned earlier, the original meaning of watermark is a mark embedded in the paper itself, not part of the image printed upon it, as is the meaning of the term as appropriated by the computer industry.

It must be a special watermark designed to interfere with the scanner matrix. The document can be scanned, but the quality is bad, and OCR does not work. The design is most probably proprietary.

Yes, I was wondering if that was the intent. It's common nowadays (at least here in the States) for financial institutions to issue checks that have include in their background some text (typically the words "VOID" or some such) delineated in varying halftone patterns that are virtually invisible to the human eye but that become quite stark when reproduced by a photocopier.

...

There are also some special fonts designed so that the human eye can read it, but they can't be read by scanning the radio waves emitted by the CRT monitor - believe me, there are businesses very paranoid about such things. For example, PGP for windows support it:

Yup. I've heard of this as well. However, in this case the point is to make it difficult to "view" a CRT display by detecting its radio-frequency emissions.

...

Secure Viewer. Select this option to protect the data from TEMPEST attacks upon decryption. If you select this option, the decrypted data is displayed in a special TEMPEST attack prevention font that is unreadable to radiation capturing equipment, and cannot be saved in decrypted format. For more information about TEMPEST attacks, see the section on vulnerabilities in An Introduction to Cryptography.

It's an arms race. Every attempt to obscure information is met with a counter-measure to assist its detection. And vice versa. C'es la vie. Let the better party win. Either that, or off with their heads...

...

Carlos Robinson

Randall Schulz

Carlos E. R.

15:07

New subject: [SLE] How to avoid copying/scanning printed paper ?

The Saturday 2005-02-19 at 18:11 -0800, Randall R Schulz wrote:

...

...
It must be a special watermark designed to interfere with the scanner matrix. The document can be scanned, but the quality is bad, and OCR does not work. The design is most probably proprietary.

Yes, I was wondering if that was the intent. It's common nowadays (at least here in the States) for financial institutions to issue checks that have include in their background some text (typically the words "VOID" or some such) delineated in varying halftone patterns that are virtually invisible to the human eye but that become quite stark when reproduced by a photocopier.

¡Ah! Here there has been cases with paer money, you know, Euros, Dollars, etc. Well, euros I don't know, but the one we had before, pesetas, certainly.

...

...
There are also some special fonts designed so that the human eye can read it, but they can't be read by scanning the radio waves emitted by the CRT monitor - believe me, there are businesses very paranoid about such things. For example, PGP for windows support it:

Yup. I've heard of this as well. However, in this case the point is to make it difficult to "view" a CRT display by detecting its radio-frequency emissions.

Correct. I wonder if TFT displays are vulnerable :-?

...

...
Secure Viewer. Select this option to protect the data from TEMPEST attacks upon decryption. If you select this option, the decrypted data is displayed in a special TEMPEST attack prevention font that is unreadable to radiation capturing equipment, and cannot be saved in decrypted format. For more information about TEMPEST attacks, see the section on vulnerabilities in An Introduction to Cryptography.

It's an arms race. Every attempt to obscure information is met with a counter-measure to assist its detection. And vice versa.

Offices can have a grounded wire mesh inside walls, and glass windows a thin metalissed film, to stop radiation going out - or in. I know they had such a thing, because mobile phones - I think you call them something different, what was it... ah, cellulars - did not work inside.

...

C'es la vie. Let the better party win. Either that, or off with their heads...

:-) -- Cheers, Carlos Robinson

Randall R Schulz

20:08

New subject: [SLE] How to avoid copying/scanning printed paper ?

Hi, Carlos, On Sunday 20 February 2005 07:07, Carlos E. R. wrote:

...

The Saturday 2005-02-19 at 18:11 -0800, Randall R Schulz wrote:

...
...
It must be a special watermark designed to interfere with the scanner matrix. The document can be scanned, but the quality is bad, and OCR does not work. The design is most probably proprietary.

Yes, I was wondering if that was the intent. It's common nowadays (at least here in the States) for financial institutions to issue checks that have include in their background some text (typically the words "VOID" or some such) delineated in varying halftone patterns that are virtually invisible to the human eye but that become quite stark when reproduced by a photocopier.

¡Ah! Here there has been cases with paper money, you know, Euros, Dollars, etc. Well, euros I don't know, but the one we had before, pesetas, certainly.

Nowhere is the "arms race" aspect more stark than in the design of U.S. currency. The armamentarium now includes microprinting, watermarks (real watermarks), color fibers in the paper, color-shifting inks, embedded security thread. The one thing our currency does not use as an anti-counterfeiting technique is the variant half-tone pattern. That's because currency is not printed using half-tones. If this stuff intrigues you, check out http://www.moneyfactory.com/newmoney/main.cfm/currency/new20 and http://www.moneyfactory.com/newmoney/main.cfm/currency/new50.

...

...
...
There are also some special fonts designed so that the human eye can read it, but they can't be read by scanning the radio waves emitted by the CRT monitor - believe me, there are businesses very paranoid about such things. For example, PGP for windows support it:

Yup. I've heard of this as well. However, in this case the point is to make it difficult to "view" a CRT display by detecting its radio-frequency emissions.

Correct. I wonder if TFT displays are vulnerable :-?

Probably not. The reason the technique can be applied to CRTs is that they are particle accelerators and the energy levels they employ are very much higher. They operate by modulating the electron beam at radio frequencies. This in turn produces radio frequency emissions which, if not shielded, are quite easy to detect at a distance and use to reconstruct the display. In comparison, LCD displays are solid state devices operating with low current and low voltage. The illumination source is the highest-power component in those devices and even it consumes far less power than a comparable sized CRT.

...

...

...
It's an arms race. Every attempt to obscure information is met with a counter-measure to assist its detection. And vice versa.

Offices can have a grounded wire mesh inside walls, and glass windows a thin metalissed film, to stop radiation going out - or in. I know they had such a thing, because mobile phones - I think you call them something different, what was it... ah, cellulars - did not work inside.

That's called a Faraday cage.

...

...
C'es la vie. Let the better party win. Either that, or off with their heads...

:-)

-- Cheers, Carlos Robinson

Randall Schulz

Carlos E. R.

21 Feb 21 Feb

02:01

New subject: [SLE] How to avoid copying/scanning printed paper ?

The Sunday 2005-02-20 at 12:08 -0800, Randall R Schulz wrote:

...

If this stuff intrigues you, check out http://www.moneyfactory.com/newmoney/main.cfm/currency/new20 and http://www.moneyfactory.com/newmoney/main.cfm/currency/new50.

Yep, I'm intrigued. I'll have a look. :-)

...

...
...
Yup. I've heard of this as well. However, in this case the point is to make it difficult to "view" a CRT display by detecting its radio-frequency emissions.

Correct. I wonder if TFT displays are vulnerable :-?

Probably not. The reason the technique can be applied to CRTs is that they are particle accelerators and the energy levels they employ are very much higher. They operate by modulating the electron beam at radio frequencies. This in turn produces radio frequency emissions which, if not shielded, are quite easy to detect at a distance and use to reconstruct the display. In comparison, LCD displays are solid state devices operating with low current and low voltage. The illumination source is the highest-power component in those devices and even it consumes far less power than a comparable sized CRT.

I know :-) But the vga cable is still the same as for a CRT, and perhaps it can be detectable. Much less power, and mixed signals, but perhaps usable.

...

...
...
It's an arms race. Every attempt to obscure information is met with a counter-measure to assist its detection. And vice versa.

Offices can have a grounded wire mesh inside walls, and glass windows a thin metalissed film, to stop radiation going out - or in. I know they had such a thing, because mobile phones - I think you call them something different, what was it... ah, cellulars - did not work inside.

That's called a Faraday cage.

Heh, I knew that before I was 14 year old :-p The neat thing about it is that we knew not that they had it installed, it was disguised. We learnt about it when we noticed the "side" effects, like cellulars not working inside - till they installed repeaters inside, because the company issued cellulars to us. -- Cheers, Carlos Robinson

James Knott

03:32

New subject: [SLE] How to avoid copying/scanning printed paper ?

Carlos E. R. wrote:

...

I know :-) But the vga cable is still the same as for a CRT, and perhaps it can be detectable. Much less power, and mixed signals, but perhaps usable.

Those cables also have shielding and chokes, to suppress RF, so as to prevent interference, that will greatly reduce that signal.

Franky Goethals

20 Feb 20 Feb

07:51

New subject: [SLE] How to avoid copying/scanning printed paper ?

On Saturday 19 February 2005 23:01, Carlos E. R. wrote:

...

It must be a special watermark designed to interfere with the scanner matrix. The document can be scanned, but the quality is bad, and OCR does not work. The design is most probably proprietary.

That's what i'm searching ! Now i still need to find it :-) If you encountered it already, please point me to it. Thanks in advance & greets, Franky. -- _________________________________________________________ GOETHALS Franky Driegaaienstraat 104 B-9100 SINT-NIKLAAS B E L G I E Verantwoordelijke MVS Support voor Euroclear Bank Secretaris GSE Z/OS Systems Working Group Privaat doeleinden & GSE Workgroup : Tel. : 32 - (0)3 / 776.65.17 GSM : 32 - (0)473 / 98.90.24 Mail & MSN : franky.goethals@telenet.be http://gsezos.dyns.cx Professionele doeleinden : Tel. Werk : 32 - (0)2 / 224.15.92 Mail werk : goethals_franky@euroclear.com http://www.euroclear.com Registered linux user #378931 (counter.li.org) _________________________________________________________

Carlos E. R.

15:09

New subject: [SLE] How to avoid copying/scanning printed paper ?

The Sunday 2005-02-20 at 08:51 +0100, Franky Goethals wrote:

...

On Saturday 19 February 2005 23:01, Carlos E. R. wrote:

...
It must be a special watermark designed to interfere with the scanner matrix. The document can be scanned, but the quality is bad, and OCR does not work. The design is most probably proprietary.

That's what i'm searching ! Now i still need to find it :-)

If you encountered it already, please point me to it.

No, I'm sorry. I know it exists, but I have never used it. -- Cheers, Carlos Robinson

Hans Witvliet

12:35

New subject: [SLE] How to avoid copying/scanning printed paper ?

On Sat, 2005-02-19 at 23:01, Carlos E. R. wrote:

...

It must be a special watermark designed to interfere with the scanner matrix. The document can be scanned, but the quality is bad, and OCR does not work. The design is most probably proprietary.

You can experiment with colors. If you make a raster image with bars 5 mm spaced, in light orange, and ordinary text grey, there is no problem in normally reading it, but when scanning or copying (BW) it, the orange background will become foreground. And OCR will certainly fail. Hans

Ciro Iriarte

13:44

New subject: [SLE] How to avoid copying/scanning printed paper ?

That sounds interesting Hans, how would you do it?, tools? Ciro On Sun, 20 Feb 2005 13:35:00 +0100, Hans Witvliet wrote:

...

On Sat, 2005-02-19 at 23:01, Carlos E. R. wrote:

...
It must be a special watermark designed to interfere with the scanner matrix. The document can be scanned, but the quality is bad, and OCR does not work. The design is most probably proprietary.

You can experiment with colors. If you make a raster image with bars 5 mm spaced, in light orange, and ordinary text grey, there is no problem in normally reading it, but when scanning or copying (BW) it, the orange background will become foreground. And OCR will certainly fail.

Hans

-- Check the headers for your unsubscription address For additional commands send e-mail to suse-linux-e-help@suse.com Also check the archives at http://lists.suse.com Please read the FAQs: suse-linux-e-faq@suse.com

Randall R Schulz

15:28

New subject: [SLE] How to avoid copying/scanning printed paper ?

Ciro, On Sunday 20 February 2005 05:44, Ciro Iriarte wrote:

...

That sounds interesting Hans, how would you do it?, tools?

Use GIMP--it's the Photoshop of free software. It's included in the SuSE distributions.

...

Ciro

Randall Schulz

Ciro Iriarte

21 Feb 21 Feb

02:55

New subject: [SLE] How to avoid copying/scanning printed paper ?

Eeee, and if i'm working on a doc of 50 pages with a word processor?, should i copy 'n' paste / import each page to my GIMP image? to get the efect? Ciro On Sun, 20 Feb 2005 07:28:00 -0800, Randall R Schulz wrote:

...

Ciro,

On Sunday 20 February 2005 05:44, Ciro Iriarte wrote:

...
That sounds interesting Hans, how would you do it?, tools?

Use GIMP--it's the Photoshop of free software. It's included in the SuSE distributions.

...
Ciro

Randall Schulz

-- Check the headers for your unsubscription address For additional commands send e-mail to suse-linux-e-help@suse.com Also check the archives at http://lists.suse.com Please read the FAQs: suse-linux-e-faq@suse.com

Randall R Schulz

03:04

New subject: [SLE] How to avoid copying/scanning printed paper ?

Ciro, On Sunday 20 February 2005 18:55, Ciro Iriarte wrote:

...

Eeee, and if i'm working on a doc of 50 pages with a word processor?, should i copy 'n' paste / import each page to my GIMP image? to get the efect?

Ciro

Obviously not. You use Gimp (or whatever image processing software suits you) to produce the watermark image and then specify that image file as the OpenOffice.org Writer page background image. Randall Schulz

Ciro Iriarte

06:50

New subject: [SLE] How to avoid copying/scanning printed paper ?

Was really curious about gettin' "a raster image with bars 5 mm spaced" On Sun, 20 Feb 2005 19:04:17 -0800, Randall R Schulz wrote:

...

Ciro,

On Sunday 20 February 2005 18:55, Ciro Iriarte wrote:

...
Eeee, and if i'm working on a doc of 50 pages with a word processor?, should i copy 'n' paste / import each page to my GIMP image? to get the efect?

Ciro

Obviously not. You use Gimp (or whatever image processing software suits you) to produce the watermark image and then specify that image file as the OpenOffice.org Writer page background image.

Randall Schulz

-- Check the headers for your unsubscription address For additional commands send e-mail to suse-linux-e-help@suse.com Also check the archives at http://lists.suse.com Please read the FAQs: suse-linux-e-faq@suse.com

Hans Witvliet

10:17

New subject: [SLE] How to avoid copying/scanning printed paper ?

On Mon, 2005-02-21 at 07:50, Ciro Iriarte wrote:

...

Was really curious about gettin' "a raster image with bars 5 mm spaced"

On Sun, 20 Feb 2005 19:04:17 -0800, Randall R Schulz wrote:

...
Ciro,

On Sunday 20 February 2005 18:55, Ciro Iriarte wrote:

...
Eeee, and if i'm working on a doc of 50 pages with a word processor?, should i copy 'n' paste / import each page to my GIMP image? to get the efect?

Ciro

Obviously not. You use Gimp (or whatever image processing software suits you) to produce the watermark image and then specify that image file as the OpenOffice.org Writer page background image.

Randall Schulz

Hi Ciro,

About creating the raster-image. Have to dig deep, it was a very long tim ago that i did that excercise. And most of that material i left at my former employer ;-( But to give an indication, i created myself an (encapsulated) post-script file. (PS is a nice programming language!) First attempt was plain with vi, later on with perl and its GD library. It's a long shot, and there are probably nowadays much more easier tools to do that job. Perhaps it can be done with gimp. As example i'll include an orange grid, made with Open Office. (snap to grid, draw line, copy&paste, change color) Adjust it as you like. Hans

James Knott

19 Feb 19 Feb

20:23

New subject: [SLE] How to avoid copying/scanning printed paper ?

Franky Goethals wrote:

...

Hi Randall,

Thanks for this supplemental info.

Do you think an ordinary watermark will avoid copying/scanning my documents ? The aim is to protect my work, that noone can copy it without my permission.

Watermarks will not prevent copying. They only make it obvious that someone else's work was copied. One technique that has been used, is to print on red paper. Copiers often have problems with that.

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participants (6)

Carlos E. R.
Ciro Iriarte
Franky Goethals
Hans Witvliet
James Knott
Randall R Schulz