Dot Matrix effect. Any ideas?

I'm after some help on creating a type of Dot Matrix effect for an image.

For an example go to http://www.designchapel then click on the Portfolio archive then find job number 44 (Vodafone microsite). Image numbers 2 and 3 will give you an example of what I am trying to do.

Any help or pointers in acheiving this look would be muchly appreciated!

It's just a pattern. Similar to the "scanline" effect. Search for creating scanlines. Use a similar method for creating the "dot matrix" effect. BTW, Design Chapel look amazing.