Google researchers develop an algorithm to remove watermarks from images

There’s a lot of creativity in the world of professional photography, with unique and bold ideas defining new boundaries, but there is one thing that remains common among all: watermarks. Used as a way to protect intellectual property, professional photographers and stock photo distributors superimpose watermarks on their works to prevent it from being used without permission.

Left: with the watermark. Right: without the watermark.

Google researchers have now managed to develop an algorithm capable of erasing these watermarks from images automatically, and with impeccable precision – all in the span of a couple of seconds.

A watermark’s strength is in its consistency – that’s how it builds a brand – but Google’s algorithm exploits this strength, turning it into a weakness; essentially, the algorithm uses a pool of images to figure out which parts remain consistent – and are therefore the watermarks. Once it figures that out, the algorithm extrapolates the watermark, and can erase it out of any image with ease; as Google researchers, Tali Dekel and Michael Rubinstein, put it:

If a similar watermark is embedded in many images, the watermark becomes the signal in the collection and the images become the noise, and simple image operations can be used to pull out a rough estimation of the watermark pattern.

Google details the entire process in its paper, but also made a summary with this video:

However, stock photo distributors mustn't fret – Google has a handy solution that breaks its impressive algorithm. The key, of course, lies in making the watermark inconsistent; it’s not as simple as making small changes to the watermark’s opacity, and changing its location doesn't really work either. The best way to counter this algorithm, per the researchers, is to make random and subtle changes in the geometry of a watermark, as highlighted in this GIF and sample:

Google’s work is indeed quite impressive, but scary too; the researchers say that while making subtle geometrical changes to a watermark won’t provide guaranteed protection against similar algorithms, it will surely make the job of removing a watermark more difficult.

Source: Google Research Blog | Images via Google Research Blog

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