The way these images simulate 3D, as explained by this Website, is by superimposing the same image twice - one that is cyan, or blue, colored and another one that is red colored - over a flat 2D picture background. Since the 3D glasses that they tell you to use have two cellophane 'lenses', one colored red and the other blue, the blue part of the 3D image will, thus, not be seen by the eye looking through the blue cellophane. Likewise, the eye looking through the red cellophane will not see the red parts of the image. By the way, some of you old enough may remember that this is how they used to make 3D movies in the old days.
How does this create a 3D effect, you may ask. Well, each of our eyes see in 2D, and it is not until the brain merges and analyzes the image gathered by each eye, and takes into account how much each element in each image is distant from the same element in the other image when compared to the background, that the brain interprets what items are nearer or farther. The farther the object the closer its position is in both images and, viceversa, the closer the object the more difference in placement in both images.
Let me try to exemplify this for you. Do this for me, place your index finger, pointing upward, about 3 inches away from your nose. Close each eye one at a time and you will see your finger appears to move left to right. Now, place your finger at arms-lenght. Close your eyes one at a time, one after the other. You will notice that the finger left-to-right movement is almost null. This is how your brain interprets how far or close are the objects and also how far they go in depth.
Pretty cool, huh? Well, I was thinking right now, why do kids have to settle with the images provided by third parties. Showing the kids the images from Mars is a great start, but why not also have them do their own 3D images? I'm sure it will be very interesting to see what they can come up with. All you need to do, is have them use a photo editor program. There are free programs very similar to Adobe's Photoshop, such as Paint.NET or GIMPS, that you can easily download and install to use for this activity.
Once you have your photo editor program installed, have the students add a picture to the background layer and turn it to gray color. This will be your stage. Have them insert another layer and add a cut-out image of an object on this layer. How to do this is out of the scope of this post, but there are thousands of tutorials on the Internet on how to do this in any program. Also there is one easy to follow tutorial at the Mars 3D site.
Then, this layer with the cut-out object needs to be duplicated and both layers need to be made semi-transparent and blurred, so that, as a result you will end up with a total of three layers. Change one of the cut-out object's channels to blue and green and the other one to red. Get hold of a pair of 3D glasses, or make your own by following the instructions at http://mars.jpl.nasa.gov/mars3d/3DGlasses.cfm, put them on, and drag one of the two objects appart from the other. The farther appart that you drag onefrom theother, the nearer the object will appear to be. Play with different percentages of layer transparency until you get the best effect.
You think that was fun? Why not trying inserting more than one different object that way you could have some sticking out farther than the others? See? The possibilities are endless! You can have the students create three-dimensional family portraits, comics, animations, presentations, etcetera!