Hybrid Images: Fun with Frequency Passes

Have Photoshop or Gimp? You can make an image that looks like one thing from afar but a different from closeup. Check out the linked examples, and if you appreciate this instructible, please visit my blog for more ideas:
GoodCleanCrazy

Find two photos of faces in similar poses. Mine are below. Guy#1 and Guy#2.

Gaussian blur one image with a 10-20 pixel radius. (Photoshop 6 and Gimp command: Filter>Blur>Gaussian Blur) This filter spreads around the pixel data in the image. The resulting blurry image lacks clarity, but it is full of color and life. It is the foundation of the image. This is basically the "low spatial frequencies" of that image.

High Pass the second image with a slightly smaller radius than you used for the Gaussian blur.

(Photoshop 6 command: Filter>Other>High Pass)
(Gimp command: Duplicate the layer. Top Layer: Filters>Blur>Gaussian Blur. Layer>Colors>Invert. Change the opacity to 50%. Layer>Merge Down.)

The "high pass" image lacks color and life, but has clarity. It is the fine details of the image, and it feels flat without a foundation. This is basically only the "high spatial frequencies" of the same image.

Step 1 Mix and Match

Now we're going to make a hybrid image.

Take the "high frequency" image and set it to "Overlay" mode in a layer above the "low frequency" image.

You now have a hybrid image! Congratulations! What can you do with a hybrid image?

From several feet away, you can only discern the low frequencies of an image. The high frequencies become apparent as you approach the image. Thus you could hide one image in another from distant prying eyes.

It seems to work best to combine images with similar features (faces work great). The mind's perceptions of low and high frequencies and our parafovial sensitivity to low frequency information explains why the Mona Lisa appears to be smiling when you look slightly away from her.

More examples and explanations can be found here.

Comments

[kewlmaster38]

where is the high pass filter when using the gimp? I cant find it under filters and I dont know where else to look.

[royalestel]

In Gimp you have to do this: Duplicate the layer. On the top layer: Filters>Blur>Gaussian Blur. Layer>Colors>Invert. Change the opacity of the top layer to 50% Then Layer>Merge Down. It's a pain, but that's the way it is for GIMP.

[kewlmaster38]

thanks man!

[GreenDay]

That's really trippy...