Could someone please explain this phenomenon?

[G5Unit]

About a year ago, I used an Epson Perfection 1250 scanner to capture a strip of color changing LED lights from about 2 feet away. What I got was the uploaded image.

I recently tried to re-create the effect with an Epson Perfection 1600, yet I was unable to get the streaks of light that I achieved in the original.

What was going on in the original scan to make it come out like it did?

 

[robbieduncan]

Relatively long exposure?

 

[macuserx86]

Looks like dirty glass to me.

 

[G5Unit]

Looks like dirty glass to me.

I made sure that the top of the glass on the scanner was as clean as possible, yet there was a lot of dust underneath.

 

[jackrv]

I agree with Robbie. Looks like a longer exposure.

 

[Nostromo]

No aliens or ghosts, sorry.

 

[psonice]

It's caused by the way the scanner works. A scanner is a bit like a camera - it has a sensor to record the image, and a lens (or mirror) combination to focus the image. The difference though is that the sensor records a single line instead of a whole scene like a camera does, so it has to 'scan' down the page taking lots of one-line images as it scans the page.

If you hold something far away from the scanner, it's effectively 'out of focus'. On a camera a point of light (like the lights you were holding) turns into a blurry circle when it's out of focus, but the optics in a scanner are different - quite often they focus in a single direction, meaning when it's out of focus you get a line. This is what you captured.

It's actually possible to make a super-high-res camera (like 100 megapixels or more!) from a scanner. You take the sensor out of it, and attach it to a camera lens to focus the light. Then you mount the whole thing on a device that slowly rotates it while it's 'scanning', and it scans the scene.

Links for the curious:

http://hackaday.com/2009/06/09/130-megapixel-scanner-camera/
http://golembewski.awardspace.com/