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I have heard on some occasions that programs for digital media, such as Adobe Photoshop, embed hidden watermarks in the pictures that make it possible to spot a pirated copy and trace it to the person using that copy. This point typically comes up in discussions "GIMP vs Photoshop" which begin by someone mentioning that GIMP is free, which gets the response that Photoshop could be pirated, which is then shot down by the "they're gonna catch you via the watermarks" answer.

It seems plausible to me that this can be done at the technical level, but is it really used in the industry to find and persecute software pirates?

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  • The technology is called hidden digital watermarks. – Oddthinking Jul 28 '11 at 6:04
  • You can't crack freedom :) – nico Jul 28 '11 at 6:07
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    Is anyone seriously alleging Photoshop includes hidden digital watermarks? Can you provide an example of the claim? (And I the only one frustrated that the piracy argument is not shot down with "But that is both illegal and unethical." rather than "The boogeyman will get you.") – Oddthinking Jul 28 '11 at 7:05
  • @Oddthinking: that was part of the meaning of my comment. An opensource program being free does not just mean that it does not cost money. To me the piracy argument should be shut down with "start using and contributing to opensource alternatives and you will see that there is no need to crack software. And, if you still think you need <non-free software> that means the guys who made it did a really good job and you should support them". – nico Jul 28 '11 at 7:18
  • My understanding is that the watermarks are from the digital camera and used to trace photos containing illegal content (think Wikileaks dumps). Adobe as well as other photo editing software simply makes sure that the watermark is retained with the image even after cropping and altering. Hunting down individual user pirates is not cost effective for Adobe. The government has deep pockets when it comes to catching bad guys or people simply trying to foment rebellion. – Chad Aug 31 '11 at 20:53
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There are currently no known steganographic watermarks and you can assume that if they were discovered they would be cracked by the hacking community or their existence would be advertised so that illegitimate users could protect themselves.

Adobe Photoshop outputs files in a wide range of formats and the process of embedding hidden steganographic watermarks would need to be tailored to each file format or a subset of the most popular formats (.jpg, .gif, etc.) could be chosen by Adobe. Then you need to understand that the process of hiding a watermark within a lossy jpeg image is significantly different from hiding it within a raw or lossless image.

With a lossy image you have the option of introducing bitmap data which can interpreted by a jpeg viewer as normal artifacts of the compression/decompression process. The amount of information you can hide is then dependent upon the size of the image/file.

Let's say you want to track images produced by your software based on the license key. We could easily introduce a hashcode for a 24 bit license key such as {1234-5678-1234-5678-1234-5678} into a 120 kilobyte JPEG image with a reduction in image quality of something like 0.02% versus an unaltered JPEG.

With lossless image formats it becomes especially difficult to hide steganographic data within an image without tipping off users somehow. A gradient image acting as a control could be created by a user and then saved in all lossless formats where the individual color values of every pixel could be compared to the control image. A difference of even one bit between expected and actual color values could indicate something fishy going on and if you get something like 32 bits you could be looking at a hash of a license key or other data.

It seems more likely to me that the watermarks would be introduced within the various filters and effects supplied by Adobe and targeted at professional images upwards of 1024x768 pixels. Rather than trying to embed steganographic data at brush-stroke level for effects such as burn/dodge you could have subtle variations in full-image filters such as color-balance to hide data that would not be detectable by end users.

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Watermarks (specifically those embedded in digitally stored images, video, and audio) are more a concern of the photo/video/sound industries, and usually just an end-product of the concerned editing software. Anything that Adobe Photoshop outputs can be manipulated to remove the watermark if you messed with it enough or found and manually removed the watermark (supposing there is one).

The Adobe software suite is so unique that it is unnecessary to watermark the software itself to determine whether it's been pirated. Given just a list of files, or the results of a few file comparisons, someone could likely determine that you have Adobe's software. They could then go through their list of registered users and find whether you're allowed to use it. Watermarking would be more effectively used to track down the person who initially released the product.

Adobe has systems other than watermarks that help prevent piracy.

You probably won't get caught, but if you're very popular and produce high-quality photos that appear to have effects that only Adobe has, you might raise a few eyebrows.

I personally recommend The GIMP for 99% of situations. Adobe's programs should be used almost exclusively by professionals who need pre-built advanced functionality. If you need Photoshop, you should be working for someone who can afford it.

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  • Hello and welcome to the site. We require all answers here to be referenced. Please fix your answer by referencing your claims such as that Photoshop watermarks your files, that you can remove the watermark, that someone can determine whether Photoshop was pirated, that Adobe has other systems to prevent piracy, etc... – Sklivvz Jul 27 '11 at 8:48
  • Sure, I use GIMP as I prefer a Linux/Unix-style system, but all the windows users I know use Photoshop... – Lagerbaer Jul 27 '11 at 15:02
  • It's a pain to look everything up when you have extensive personal experience with every point of the answer... but OK, I'll find sources for you. Gimme a few hours. – Barbarrosa Jul 27 '11 at 23:23
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    Those Windows users are 1) people who legitimately need the obscure extra functionality or name of Photoshop, 2) cheap #1's, or 3) people who don't know or care about the GIMP. The GIMP would seriously suffice for most people. – Barbarrosa Jul 28 '11 at 2:45
  • Barbarrosa, this answer seems to confusing visible digital watermarking with invisible or steganographic digital watermarking. Your first two links are about the former, but the question is about the latter. Using a hex editor to remove a watermark seems like an unlikely technique. – Oddthinking Jul 28 '11 at 5:59

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