Over at that other thing that I've been doing, the subject of watermarking images comes up quite frequently (texture rippers). I've also been doing something else on the sly and my interest in watermarking has been piqued just a tad. If I can actually put these two things together, it will be awesome, but I'm going to settle for watermarking for now (and keep the rest under wraps for a bit longer).
So this guy posted a mini-tut on a simple watermarking technique. I played with it and got to know it. Once I understood his technique intimately, I did it up Stroker/WJ-style as a filter.
Read on.
----
DevIL Download:
http://openil.sourceforge.net/download.php
Put DevIL.dll in Photoshop/, Photoshop/Plug-ins/Filters/ or that one Windows directory... System32? I have DevIL.dll in my filters directy and it's all good for me. This DLL is needed for Nam's Mark to load an image watermark.
Namssor's Mark b1
TS_namsmarkb1.rar
Chuck that into your filter directory and re-start your host of choice.
BBL with some notes.
----
Watermark
There is a button to load a watermark image file and a non-editable string to show last watermark image used.
The last mark used is stored in the registry and should be automatically loaded on each invocation. I have tested with Ctrl+F but not with scripting (in an Action).
----
Watermark Threshholds
The watermark image needs to be threshholded. Since this implementation is full RGB, you can threshhold each channel individually. I did think about threshholding the whole thing at 128 under the hood, but decided on some flexibility and control.
----
Noise
These control the noise mask. Since the noise is pseudo-random, you can use Seed at the same value for the exact same noise everytime, or use different seeds for different noise in different projects or whatever. Inter is the number of interations that noise is added. N Threshhold determines whether or not a given pixel is 'on' or 'off'. Using these slider, the noise mask can have different spreads.
----
Output
These are the options for raw output. Whichever one is active for the Preview is what you get in the final output. The only two that you will really need are Noise Only and Marked Image, but I tossed in the other two for detective reasons.
----
Defaults
These will save or load slider values only in registry settings - SLIDER VALUES ONLY! No affect on the watermark image or output options.
----
And finally Strength all by its lonesome. The higher the value, the more mask + noise will affect the final image output.
----
How to check a Suspect image:
Load up your original in PS. Put the Suspect image in the same document on a new layer above the original. Set the blending mode of Suspect to Difference. Above this, add a Levels adjument layer and bring Output 255 all the way down to 10 or so.
Above all of that, add a new layer and fill with any colour your precious heart desires. On this layer, fire up Namssor's Mark and use the *exact* same settings that you used to watermark your work. For Output, use Noise Only. Since outputting Noise Only, only the Noise sliders absolutely have to be exact. Click OK.
Once back in the Layers palette, set the new Noise Only layer to Difference. Maybe, just maybe, your watermark will show. Now, I can do the watermark check with a filter, but I decided on letting you use Photoshop's tools for this. I did this for very specific reasons (I'll let you ponder why).
In the tests that I did, the results were far more positive than I was expecting. There is still some noise, but definitely more than enough visual to conclude in the affirmative that my mark does indeed exist in the suspect image.
I even tested the pseudo-randomness and that pulled through like a charm.
But the one thing that I didn't test is putting it in an Action and Batching. For where I'm at, testing positive with Ctrl+F is enough.
Another thing I did was try to break the watermark. This is proving to be far more difficult than I originally thought. Even against my assaults, the watermark remains largely intact. One thing that really helps is that I did this in RGB.
I'm smart, understand the method intimately, coded it - and I'm having a hard time defeating it. Kudos for that I guess. Does that make me less of a coder? Jeez, I feel so inadequate all of a sudden. :sniff: I need a hug.
----
PC Win only. I'm still WinXP SP3 and it works for me. No idea if it will work with any flavor of Vista in particular.
Photoshop CS2 and it works for me. No idea if it will work with higher/lesser versions of PS. Also, it should work with other hosts but I have no real idea which ones (PSP, Gimp, etc).
It does use the registry for a handful of values. This might come into play if you keep your computer on lock-down.
I actually tossed in far more error-checking than I usually do.
posted 04-01-2009 19:22
