Hidden watermarks? (how to)

[monikoke]

Hello guys! This is my first post around here. I know some people do this, but I have no idea how to achieve it. Say I am selling a gallery online (100 pics). Can I save a small "mark" on the code of a random picture (which would be automatically placed when someone buys the set), which could later be used to trace whoever is sharing the gallery? Its what they call a hidden watermark.

How do you guys think this could be achived?


Thanks so much for your help!!!


- Monika

[bluebook18]

welcome to gfy, here's a bump

[King-Servers]

it is not so hard
https://www.youtube.com/watch?v=Xgehvx3oKc0

[monikoke]

welcome to gfy, here's a bump

Thanks!!!

[monikoke]

it is not so hard

No... this is not what I want. I don't want to remove a watermark. I want to place a watermark (different for each customer who downloads the gallery). It has to be a hidden watermark (can not be seen in the picture, but it is hidden in the binary code itself).

[codingwelt]

I know this thread is pretty old, but have a look at it. There's some really useful information in there: /showthread.php?t=990150

[monikoke]

I know this thread is pretty old, but have a look at it. There's some really useful information in there: /showthread.php?t=990150

Thanks a lot! Its very useful, although my original question still remains...

[brandonstills]

I believe you are referring to "steganography". You basically manipulate the image in a way that they can't see the difference. Some techniques can even survive destructive operations like cropping, brightness, rotation, noise, overlays, etc.

[monikoke]

I believe you are referring to "steganography". You basically manipulate the image in a way that they can't see the difference. Some techniques can even survive destructive operations like cropping, brightness, rotation, noise, overlays, etc.

Yup... but how can that be achieved automatically? That is, a server would have to do it for every customer.