Why do many galleries have a grid on the background?

Question

JavaScript

I noticed a long time ago that in many galleries, especially full-screen galleries, there is some kind of grid of round dots with different radii on the background of the picture - smaller from below and from above, larger towards the center of the screen (similar to gradient emulation). when scrolling the picture, the grid remains motionless, it is more noticeable in light areas.
what is this?
artistic idea? problems with the video card / directX / some other software components?
maybe protecting the browser from a full-sized picture, so that for example it was impossible to “draw” the desktop?
in all browsers that I tried (IE9, Opera, Chrome, FF) the effect is present.
on other computers like the same picture.
for an example , you can look here
I tried to google, but I didn’t find similar questions, but it’s terribly interesting why

Answer 1

The resolution of monitors varies greatly, and if the server only serves 1 image of a certain size, this is an easy way to hide the shortcomings of a small image on a high resolution read screen. For example, at home I have a monitor with a resolution of 1024x768 and at work 1920x1080, we take something in between, let it be 1440x900, put a layer with dots on top, but if now I look at this picture from work, it will increase by 60% and to hide the artifacts of such an increase make a layer with dots.

Answer 2

In the example gallery, the grid is overlaid on top of the image by the browser ( div[class=fp_overlay] ).
At the same time, the picture itself is clean.
Copy protection non-fuzzy? Rather, the authors of the gallery believe that it is more beautiful.

Answer 3

It looks like a banal protection against copying pictures.

Answer 4

Most likely the author's idea. Presumably mowed for raster printing a la Roy Lichtenstein.