Create new layer, fill with white, move white layer BELOW layer with black dots, then merge all layers (Ctrl-Shift-E).

Go to effects - Blur - Gaussian blur, apply blur with about 3-4 pixels.

Open Levels (Ctrl-L) and adjust them carefully so that dots are sharpened and rounded. For me, the best result is 144 and 161.

Remove white. You might know how to do it from my previous tutorials, so in short:
- select all (Ctrl-A)
- copy (Ctrl-C)
- turn on quick mask (Q)
- paste (Ctrl-V)
- turn off quick mask (Q)
- remove selection (Del)
- make layer black (Ctrl-U, set Lightness to -100%).

Now copy black dots to our wallpaper, and invert (Ctrl-I) to make dots white.