I know water mark the photograph is one method to protect ones copyright over the picture. is there any other technique through which one can prevent or detect the plagiarism of photos.
4As is, your question is pretty vague. What do you expect of a 'protection mechanism'? Do you wan to assess proof of ownership for exact copies, modifications and derivative works, what kind of modifications? What kind of watermarking are you expecting, visible or invisible? Watermarking is a complicated matter and depends a lot on the use case.– M'vyOct 10, 2017 at 8:43
i edited your tags to be more specific - if you search those tags here, you will see a lot of options– schroeder ♦Oct 10, 2017 at 8:43
Watermarking is not one method but many of them. You can add hidden marks which are detected by crawling the whole internet for pictures, or you can put visible mark to say that it's copyrighted material.– AriaOct 10, 2017 at 8:58
There's not any fool proof way. If you upload or host a photograph on a server and it's accessible by users or it's accessible by anyone with an internet connection the content becomes fair game for anyone to take/reuse/re-upload/edit/copy.
Here are some mechanisms that certainly slowdown people form misusing your content:
Watermarking (as you mentioned)
Stenography can be used to hide information in the photo that lets you do an image search via google's image search and always find instances of your photo, then you can ask the user to remove the misused content.
Preventing users from taking screenshots (poor form and i.e only)
Preventing users from right-clicking image
1Forget steganography. Steganography is not a security feature, its goal is to make information statistically hidden in a collection of images, so that there is no efficient way to distinguish which image contains information and which does not other than running the decoding process (which is time consuming).– M'vyOct 10, 2017 at 15:06
That's the point. One must hide the information so that others do not know it's in the image. Once you encode the content you should be able search for it based on your encoding method, much like i mentioned in the answer. I will say that it's REALLY out of the way and very similar to a hidden watermark. This is what movie agencies use on movies they give to critics for advanced screening and if they movie is leaked they will know exactly who leaked the content as it is singed with a digital signature iirc.– carOct 10, 2017 at 15:51
1There is a critical difference about watermarks and steganography. Steganography aims at reducing the amount of (statistical) alteration made to the image so that one cannot infer the presence of the mark. Whereas in watermarking, the goal is to have a resistant mark to be able to maintain proof of ownership over modifications of the media. This goal is not compatible with the goal of steganography. Obviously the two techniques share some concept, but they are not the same.– M'vyOct 11, 2017 at 8:51
You've said the same thing twice. With Stenography you sign the image with information. Someone misuses the information and climes the the work as their own. To prove ownership you decode the hidden message, or show that their content does not decode properly ect. This is a simple example. The fact is that one can use all of the listed methods to help slowdown the misuse of their content and track it, which was the point of my original answer. IMHO if you have more to discus I think it's time we take this to a chat so i can make edits to my answer if need be.– carOct 11, 2017 at 12:59
@car I believe M'vy's point is that it is desirable for a watermark to survive changing format (eg if someone changes your watermarked png to a jpg it would ideally still be there), whereas stenography just wants to keep data hidden, and modifying something enough to survive format changes would likely make it much easier to discover. Oct 11, 2017 at 13:14