8: Interlace Effect
The above picture is courtesy of www.northarabians.com.
1. Load Photoshop and open your image.
2. Go to (File, New) and and start a new document with a width of 1 pixel and a height of 4 pixels. Magnify your new document up to 1600% by either scrolling the mouse up or pressing 'Ctrl' and '+'. Now choose the Pencil tool (or press 'B'), make sure the foreground is set to a black and draw in the top two blocks of the document with your foreground color, as so:
3. Press 'Ctrl' and 'A' (or go to Select, All) to select the whole document. Now go to Edit, Define Pattern, give your pattern a name and click on OK.
4. Go back to your original image and insert a new layer (Layer, New, Layer). Press OK. While still on this new layer go to Edit, Fill. Select your pattern from the list of patterns and choose an opacity of about 10% to 30%. Click OK. Finally, choose Overlay from the menu in the Layers box (right under the Layers tab).