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A comment on Making Visible Watermarks More Effective. Parent comment

Re:Making Visible Watermarks More Effective by fake-name on Thursday August 17, 2017 @02:53PM (#15039705)
The point of the article is that, for sites with a huge image corpus, if they apply some randomization to the watermark for every image, it's much more challenging to recover a un-marked image.

Right now, sites like shutterstock and other image sites apply the same watermark to every image, making it quite easy to computationally extract the watermark, and then apply the inverse transform to marked images.

If the watermark is permuted on a per-image basis, it becomes much harder, since you can't extract the watermark from a single image.

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Re:Making Visible Watermarks More Effective by jotato on Thursday August 17, 2017 @03:00PM (#15039781)
I wonder what would happen if I took 1000 copies of the same image that is using a warped mark and ran it through the algorithm....
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Re:Making Visible Watermarks More Effective by lightbyte on Thursday August 17, 2017 @03:11PM (#15039879)
The algorithm is calculating the mean of the set of images, so putting 1000 copies of the same image will do absolutely nothing
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Re:Making Visible Watermarks More Effective by colejohnson66 on Thursday August 17, 2017 @10:09PM (#15042911)
Couldn't I run the result through Photoshop with some "Content Aware Fill" on the remaining spots?
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Re:Making Visible Watermarks More Effective by jotato on Thursday August 17, 2017 @03:30PM (#15040034)
i mean to remove the watermark on that specific image
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Re:Making Visible Watermarks More Effective by azdle on Thursday August 17, 2017 @03:46PM (#15040178)
The idea is to use a randomly-warped per-image watermark. So in theory, there's exactly one distinct watermark per image, so 1000 of the same image would have the same watermark.
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Re:Making Visible Watermarks More Effective by Kdparker on Thursday August 17, 2017 @04:35PM (#15040708)
It would be easy to change that hash by modifying one pixel per image (pick one that is unaffected by the watermark).
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Re:Making Visible Watermarks More Effective by azdle on Thursday August 17, 2017 @04:42PM (#15040784)
I'm not sure what you're suggesting. Change what hash? Of the image? I can't think of how that could help with removing a watermark.
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Re:Making Visible Watermarks More Effective by LukeShu on Thursday August 17, 2017 @05:52PM (#15041380)
jotato: I believe this can be defeated by tricking the watermarker in to generating 1000 distinct watermarks for the same image.

azdle: That won't work, because "there's exactly one distinct watermark per image, so 1000 of the same image would have the same watermark."

Kdparker: So subtle alter the image, to trick the watermarker in to thinking the image isn't the same, thus generating more distinct watermarks for the (effectively) same image.

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Re:Making Visible Watermarks More Effective by baddox on Thursday August 17, 2017 @10:45PM (#15043104)
If you have the original image, the problem is already solved. If you don't have the original image, then all you will be doing is submitting the watermarked image and having the site apply another random watermark to it.
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Re:Making Visible Watermarks More Effective by 0x0 on Thursday August 17, 2017 @03:44PM (#15040161)
They would probably use the same warp every time on a specific image, so that you can't average it out across multiple download sessions.
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Re:Making Visible Watermarks More Effective by AgentME on Thursday August 17, 2017 @03:42PM (#15040146)
The algorithm takes a bunch of pictures, figures out what's in common between them, and then removes that part. If you give it only many copies of the same image, it will find that the whole image is in common between the images, and subtract out the entire content.
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Re:Making Visible Watermarks More Effective by throwaway91111 on Thursday August 17, 2017 @04:06PM (#15040374)
Surely the watermark could also be ugly and irreversible; ie clamp to white.
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