Sunday March 27, 2005

Transparent Screen

The latest fad that's sweeping the blognation seems to be the transparent screen trick: take a photograph of whatever sits behind your screen, then carefully crop and tweak the image and use it as your desktop background.  The result is the illusion that your screen is transparent, with your icons and windows floating in space.  Unable to resist, I spent an hour or so moving my monitor out of the way, taking photos in various lighting conditions, and massaging the best photo until it matches up quite well.  Here's the result:

In the end, I have to admit that I don't find the results very convincing.  That's disappointing because my monitor setup seems particularly well suited to this trick.  The screen is high off the desk and has a narrow border, which should make it easier to get the illusion of floating in space.  On top of that, what's behind it ought to be good raw material for the illusion: the horizontal brown board in the middle and the edge of my desk at the bottom, both passing unbroken through the screen, as well as the prominent vertical copper pipe should all help produce the impression of continuity.  In fact, I think the illusion is pretty convincing in the photograph above, especially in the lower left corner.  (The colors don't match exactly in the image, but they're actually more closely matched than that—my screen photographs blueish.)  It's not as convincing in person, though.

There are several reasons why.  A lot of the photos of this trick out on the web (see the gallery linked above for a large collection of them) involve laptop screens, which are generally pretty small.  My screen is large enough that it fills most of the middle of my field of vision, so that the transition between background and background image takes place in my peripheral vision.  That seems to weaken the illusion a lot.  More importantly, the screen is about 24" away from my eyes, but the wall behind is another 26" behind that.  So, when my eyes are focused on the screen, the background is very out of focus, breaking the continuity between the two backgrounds.  This is especially true when I look with both eyes because of the retinal disparity—I see one screen, but two walls, at least one of which doesn't line up with the image on the screen—but even when I only have one eye open, the screen is in focus while the wall is blurry.

It appears in some of the photos I've seen (like this one or this one) that the point of view is at least several feet away from the screen.  This would obviously reduce the depth-of-field and retinal disparity problems—I'll bet this illusion works really well with a screen that's right up against a background and seen from across the room—but then the illusion won't work for somebody sitting and using the computer.  That's because the image on the screen and the background only line up from one particular point of view—not just a particular angle, but also a particular distance.  The generalization seems to be this: the closer your screen is to the background, and the further your point of view is from the screen, the better the illusion of transparency is.

I expected some of these problems going in, but I was hoping to get a fairly convincing photo to use as my background image.  I think I have to declare failure.  My setup just doesn't lend itself to this optical illusion.  Still, it was an interesting experiment.  (hat tip: Boing Boing)

[Update: Wow, check this out.  It looks like there's a live camera (mounted on the back of the screen?) providing the desktop background image, but I can't see how that would work—I'd expect a strong fish-eye effect.  The web site appears to be a video production company that does some special effects (see here, for example), so my guess is that's it's faked up somehow.  Pretty cool, though.]

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Wow, you have a really huge monitor. I wonder why most of the other screens are of laptops - are laptops really that much more popular?

Moreover, why is this trick so fun? Do we secretly want to make our computers disappear? (Will the the next hottest Mac laptop be the "you'll never know it's there" camouflage model?) What would be really amazing is if you could change the background on, like, MS Word so that it looks like you're typing across your wall while you write.

Posted by: polyglot conspiracy at Mar 27, 2005 3:45:49 PM

Nice go.
I would try it,but I'm far too lazy. I would far rather have a monitor on the wall show a picture of what is outside the other side of the wall. That is just me.

On, and over the last two years, laptops have outsold desktops, but just barely.


Posted by: Kelly at Mar 28, 2005 6:56:10 PM

I don't understand the fascination with laptops. They are underpowered, difficult to customize or add to. The only advantage a laptop has is portability. If that is what you need fine, but if you need serious computing power a laptop cannot keep up.

My desktop has 410gb of hard disk, two 19" flatscreen monitors 1gb of RAM - There is no way a laptop can even compete. Right now I'm just waiting for dual-processor chips to get reasonably priced before I invest in a dual-processor 64 bit chip with 4gb of RAM and probably by that time 1TB of hard disk space.

Posted by: Blinger at Mar 30, 2005 3:00:49 AM

The reason laptops are used is that you can fold down the screen, take the picture, and move it back up to the original with relative ease. Try doing that with an LCD or, forbid, a CRT: You'd have to accurately position a heavy piece of equipment. Not quite as easy as just folding down a screen.

Posted by: Darryl McAdams at Mar 30, 2005 9:35:47 AM

No, this unconvincingness is because of the lack of depth on the monitor, not the blurriness or any else. if the LCD was a 3d one and you had the craziness to make a 3d model as your background, this will work.

But a flat LCD screen has no depth. As soon as you move your head, the picture moves, and there is no 3d.

unless, they make an lcd screen with a transparent back. that would be cool! though how they would display black pixles would be a problem...

Posted by: yujin Wu at Oct 7, 2009 5:00:18 PM