1. Open a picture, anyone.
2. Goto Image > Dupiclate.
3. Another image should pop up on the canvas. On the dublicated image goto Image > Mode > Grayscale.
4. Next, goto Image > Mode > Bitmap.
5. Use these settings : Output: 72. Pixels/Inch. Use: Halftone Screen. Press OK.
6. Use these settings for the next bitmap option. Frequency: 72. Lines/Inch. Angle: 0. Shape: Round. Press OK.
7. Looks all crappy, right? Well, goto Select > All.
8. Than, Edit > Copy.
9. On the non-bitmap image, goto Edit > Paste.
10. Next, from the drop down list of blends.. Select 'Soft Light'.
11. Don't like how it looks? Lower the opacity to about.. 30-70.

You're done. xD. This works with any type of image, just not blank images.