Invisible digital watermark

[Simon Frei]

I don't know anything about how it works, I just had a hunch that this
would be something that could be in G'MIC - and it was. You best ask the
G'MIC folks about it.

Honestly, I don't really consider this very useful in the real world.
The party where you proclaim a copyright breach has to use G'MIC digiKam
to recover the copyright information, which they probably won't, and a
simple proof of ownership by comparing to an "original" (higher res,
raw, ...) picture is probably sufficient. If your picture is that
valuable, the "thief" will probably also go trough the trouble of
removing your notice from the fourier domain (which probably is
possible, as it is fourier and the original transformation
implementation is known).

On 12/05/17 15:17, Sveinn í Felli wrote:
> Maybe something similar to image steganography could be used?
> That is a process where one can embed encrypted message/image into a
> picture. Pixelknot is such an OSS-application for Android, see
> <https://guardianproject.info/apps/pixelknot/>
>
> Simon, do you know how well the Fourier markings survive through
> modifications by image sharing services?
>
> Regards,
> Sveinn í Felli
>
> Þann fös 12.maí 2017 12:38, skrifaði Louis A. Turk:
>> On 05/12/2017 07:05 PM, Gilles Caulier wrote:
>>> Very interesting. Please comment this entry in bugzilla accordingly :
>>>
>>> https://bugs.kde.org/show_bug.cgi?id=268981
>>>
>>> Thanks in advance
>>>
>>> Gilles Caulier
>>>
>>> 2017-05-12 12:03 GMT+02:00 Simon Frei <freisim93 at gmail.com>:
>>>> There is a G'MIC filter that embeds text in the fourier domain, it is
>>>> called "Fourier watermark" (and "Fourier analysis" to retrieve the
>>>> info): https://gmicol.greyc.fr/
>>>>
>>>> On 12/05/17 11:35, Gilles Caulier wrote:
>>>>> You cannot. Invisble watermark use wavelets encoding methods which
>>>>> are
>>>>> patented in US and impossible as i know to code in open source...
>>>>>
>>>>> Best
>>>>>
>>>>> Gilles Caulier
>>>>>
>>>>> 2017-05-12 10:42 GMT+02:00 Louis A. Turk
>>>>> <louisaturk at firmanelohim.org>:
>>>>>> How can I do invisible digital watermarking with digikam5 as
>>>>>> mentioned
>>>>>> here:
>>>>>> https://docs.kde.org/trunk5/en/extragear-graphics/digikam/using-dam.html#using-dam-copyright
>>>>>>
>>>>>>
>>>>>> How can I do a regular watermark?
>>>>>>
>>>>>> drl
>>>>
>>>>
>>
>> Thank you Gilles and Simon. Hopefully, the impossible may be possible
>> after all.
>>
>> drl
>>
>