6
$\begingroup$

The pattern seems consistent with the magnetic force lines of a bar magnet. enter image description here

$\endgroup$
2
  • $\begingroup$ Was your camera flash on? Also, can you check if the same pattern appears if you take a picture of a piece of paper or some low light/contrast thing? $\endgroup$ – user12029 May 11 '15 at 22:33
  • $\begingroup$ No, the flash was off and other images look fine. $\endgroup$ – mightwork May 11 '15 at 22:37
10
$\begingroup$

That looks like a Moire pattern to me. You have a camera with a grid of pixels on the imaging element and a screen with a grid of (colored) pixels. These elements don't line up exactly, so you get the odd patterns.

Try taking another image with the camera slightly twisted along the lens axis or slightly angle the lens axis to the laptop. If it's a Moire, then the image will look quite different in both cases.

And if I am understanding it right, these type of Moire patterns are made as a result of overlapping of curved grid lines

No, they're similar to aliasing effects. Imagine taking a picture of a grid. The optics will put a picture of the grid onto the imaging sensor (CCD). At some distance/zoom, the lines of the grid will be almost exactly the same distance apart as the CCD elements. If the lines fall between the elements, they won't be seen easily. If they fall exactly on the elements, they are seen easily.

But your laptop screen isn't all the same distance from the lens. It's flat, so the edges are farther than the center is. This means the angular separation of the LCD pixels changes from the center to the edge. This apparent change in the grid separation from one part of the image to another makes the bright/dark/bright/dark areas appear. They're curved because the apparent grid size changes with distance (so you get sort of circular patterns).

Your original image looks to me to be a very lucky shot. The grid in the middle is free of much distortion over a large area. Pretty neat.

$\endgroup$
3
  • $\begingroup$ being trying it for some time now. Cant seem to reproduce the effect. And if I am understanding it right, these type of Moire patterns are made as a result of overlapping of curved grid lines ? $\endgroup$ – mightwork May 11 '15 at 22:39
  • 1
    $\begingroup$ I would try to turn on the (digital) viewfinder and while looking at it move the camera to different distances. I would expect there to be certain distances where the screen showed odd patterns. $\endgroup$ – BowlOfRed May 11 '15 at 22:45
  • $\begingroup$ imgur.com/MNPNdD0 This looks more like it. It seems it was just coincidence that the original pattern resembled magnetic force fields. $\endgroup$ – mightwork May 11 '15 at 22:53

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.