TUTORIAL: stereograms – how to see unseen

Stereograms in geocaching sometimes are used to hide coordinates or some hints. The problem is, not everyone are able to look properly at picture and see hidden content. I belong to that group, however I don’t want to leave such mystery cache unsolved, I had to find some solution. My first idea was to ask someone for help 🙂 If you are home alone at the moment and there is no one who can help you, help yourself!

Although the description looks long, doing all the following operations (after mastering them) should take up to one minute.

We will use graphic program called GIMP (www.gimp.org) – it’s free and available on few operating systems.

First, download stereogram and open it with GIMP.

  1. Open layers window by clicking menu: Windows -> Dockable Dialogs -> Layers (or use keyboard shortcut: Ctrl+L)
  2. Use Duplicate Layer function: it’s available in Layers -> Duplicate Layer menu (or use keyboard shortcut: Shift+Ctrl+D).

    As the effect, there should be new layer (in our case named “stereogram.jpg copy”).
  3. Select newly created layer (it should be automatically selected after adding). Next, in layers window, select Mode menu and choose Difference mode.
    It should cause that our picture turns all black.
  4. Select Move tool from Tools -> Transform Tools -> Move menu (you can also use keyboard shortcut M).
  5. Click somewhere inside picture window area (but not in picture) and start moving picture using arrow keys to the left or to the right (when you choose direction, stick to it) and… wait for the effect. After moving your picture several dozen pixels, hidden context should reveal. In our case:

Those who are able to see content of stereograms, can see this in different way – they say it’s kind of 3D effect. Fortunately – although another way – you and I can also see what was invisible until now 🙂

Despite above, you can also use some websites. They are not perfect (nor my way), but sometimes they are helpful. Not all stereograms can be decoded with these websites, but it’s worth trying. Two sample websites are:

These websites seems simple and I don’t think there is need to describe how to use them, but if you don’t agree – let us know by leaving a comment.

Sample stereogram was generated on website http://www.hidden-3d.com/index.php?id=msg_gen.

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