Secret Decoder Glasses
Your art supply box may already have all you need.
Secret Message Decoder - Not 3D
Before we make some 3D images, let’s start with a color filter demo by making and decoding secret messages with Crayola markers and some filters I bought from Amazon. Well, “secret” anyway.
We mentioned before that for 3D images, we need to pick two opposing colors for the image (and glasses). In this example we need two (or more) marker colors and one corresponding filter color. In this post, I’ll use yellow for the secret message and blues/greens for the filter and cover, and follow up with a green message with red/orange filter and camoflauge.
You can use any markers, crayons, colored pencils and any filters you can find BUT you may need to experiment first to ensure your choices are compatible. Not every red filter will be compatible with every crayon in the box. So before you unveil this to a judgmental audience of children, go through your stash to pick the best available color combinations.
A sample of marker colors paired with three colors of filter. Lime and yellow were good color choices because they’re light when applied to the paper, but the filter actually makes them look darker.
In this example I will choose a blue filter with yellow text. I have at least two blue markers for playing with the cover-up design and could probably get away with a purple or light green as well. It’s good to have options since it pays to have fun with the cover-up.
Upper left: An urgent message written in Crayola Yellow and Laser Lemon. Upper right: The plain yellow is more prominent when viewed through my blue filter. Lower left: Both messages obscured with blue and green patterning. Lower right: The hidden message, decoded.
Here you see I wrote a secret message (Hello, World!) and camouflaged it with blue and green lines. Why did I not use a solid block of color? Several reasons.
The markers are somewhat transparent, so a block of color would clearly show the message as bleed-through. We need the design to be a bit busy to distract from the incomplete coverage.
If we tried to fix this by using an opaque marker and we cover the message too well or the message and the camouflage mix together, the decoder will not work.
Crayola-on-Crayola worked here, but if you’re having trouble try mixing mediums. Write the message in ballpoint pen and cover in marker or crayon or colored pencil or a combination thereof.
Another good combination is red/green. Note I used the light green (“lime”) here because the regular green marker was very strong, and I don’t want to have to use too strong of colors in the cover-up. The filter is equally effective on red and orange so I can have a bit more fun with this version.
Red/green example.
In the examples here, we’re not exactly super spies. Squint long enough at the obscured message and you can probably figure it out without the decoder. But the more care you take, the more fun they become. This demonstrates the concept quickly and cheaply enough - but if you’re super concerned about security, have a budget or want to impress, Rainbow Symphony will do custom secret message cards. Otherwise, Amazon has tons of cheap colored filters.
So, how does this get us to 3D?
Look at our filter test again - a given filter will obscure certain colors and enhance others. The blue filter swallows up the blue and electric blue markers (well, mostly) and makes yellows, oranges and reds stand out. The red filter makes red colors disappear but lets blue and some greens come through clearly. You are looking for a pair of colors where each eye allows one color through, and blocks the other. With this selection of colors (red and cyan) the pass-through image on both sides looks black, while ghost or incomplete filtering is minimized.
This is how you will get two slightly different, offset pictures to each eye for the brain to process into a 3D-ish picture. In the case of this line drawing, the 3D effect is basically the seal outlines floating above the page - I tried to make it more interesting by making three layers, but don’t expect a smooth, immersive 3D experience.