how to detect a given set of watermarks in images

i need to know whether images entered watermark or not

[Image Analyst]

Is the watermark one of yours, that you know how it's constructed and where it is? Or do you just want to find any watermark (visible or invisible) that anyone in the world might have put into any image?

[kishore reddy]

i want to find any watermark(visible or invisible )that anyone in the world might have put into any image