Hiding Data into Images

A year or two ago computer magazines were writing about the possibility to add secret data to some image file formats. This was (and still is?) done by adding some empty space to the file and then adding the desired data into it. Well I've discovered another method to do the trick!

Step-by-step instructions for hiding

The method is actually quite simple. First take a photo or some other image. Even blank white image will do! Then choose dark grey or some another color for brush. Next write the secret text in to the image so that it will be on it's own layer. (sample images were taken from Paint Shop Pro 7)

Take the Layer Palette tool and set the top layer's visibility to almost zero, so that the text becomes invisible for human eye. Now save the file in desired format. Jpeg will do with photos and in this kind of image even gif stores it in the right way.

How to recover data

Use the highlight, midtone and shadow tool as seen above. Different settings may be required for different background images used.

Epilogue

I tested with many color/background image combinations and it seems that different images need different colors to be used. Try them by yourself to find the best combinations! I guess this is also a secure way to secretly send data to your friend, because at least at the moment there's no automated OCR programs trying to find this kind of hidden data in the internet. And probably there even won't be in this decade or so because of the nature of this trick.

Here's the example image I used above to demonstrate the method. Try to recover the Hello world text from it by yourself!

Tapani Talvitie
31.3.2004

© Copyright by Tapani Talvitie 2003-2007, Last modified 28.3.2007