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 How to add invisible water marking in images		  New Topic  Reply to Topic
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yogiyang

India
725 Posts
Posted - Jan 16 2021 :  00:02:42  Show Profile  Reply
Hello,

I have a need to implement a feature for use in which the user can add an invisible watermark in image that they create.

On researching regarding this on the internet I came across an article that explains that OpenCV can be used to add invisible watermarks to images.

And IEVision is based on OpenCV( if I am not wrong).

So how can we implement this feature?

TIA

Yogi Yang

xequte

38182 Posts
Posted - Jan 16 2021 :  16:26:48  Show Profile  Reply
Hi Yogi

IEVision includes many OpenCV features, but not all of them. More likely you can do this using standard ImageEn. What method are you looking to use insert the invisible watermark. Generally it is done by overlaying an almost completely transparent watermark image.

Nigel
Xequte Software
www.imageen.com
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yogiyang

India
725 Posts
Posted - Jan 18 2021 :  06:59:31  Show Profile  Reply
Hello Nigel,

What I am looking for is a way to watermark an image and later read the watermark back to prove the ownership of the image creator.

TIA

Yogi Yang
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xequte

38182 Posts
Posted - Jan 18 2021 :  17:45:17  Show Profile  Reply
Hi Yogi

Yes, there are a number of discussions on the web of the best way to do this. Generally, you would avoid easily circumventable options like meta-data. If you overlay an almost transparent image over the image then that is invisible to the naked eye, but can be detected by comparing the watermarked image with the source.

Nigel
Xequte Software
www.imageen.com
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yogiyang

India
725 Posts
Posted - Jan 20 2021 :  01:56:25  Show Profile  Reply
Hello Nigel,

Can we achieve this using IE I mean comparing watermark applied to an image with actual watermark PNG file?

Can you share some source sample please?

TIA

Yogi Yang
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xequte

38182 Posts
Posted - Jan 20 2021 :  23:01:33  Show Profile  Reply
Hi Yogi

Here is a simple test I did using the demo:

\Demos\ImageAnalysis\ImagesDiff\ImagesDiff.dpr


procedure TMainForm.test1Click(Sender: TObject);
begin
  Tile;
  image1.imageenview1.IO.LoadFromFile('D:\src.jpg');
  image2.imageenview1.IO.LoadFromFile('D:\out-2perc.jpg');
  image1.ImageEnView1.Fit;
  image2.ImageEnView1.Fit;
  PerformCompare();
  
  // Stretch result so easier to see
  diffs.ImageEnView1.Proc.AutoImageEnhance3( 1.0 );
end;



Here are the two source images (second one has white text drawn at 2% opacity by merging a text layer):






Here is the difference view:




Of course, being a JPEG there are encoding artifacts. If you use PNG the difference is much more crisp:




This is just a simple example. You could code a better solution by iterating through the scanlines and doing a more targeted comparison.

Nigel
Xequte Software
www.imageen.com
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yogiyang

India
725 Posts
Posted - Jan 23 2021 :  06:01:31  Show Profile  Reply
Hello Nigel,

Thanks for the code sample.

I will test it and get back if I have any other queries.

TIA

Yogi Yang
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