TV SCANLINES
Step 1: Open your working image. Switch to channel view and create a new channel (Alpha 1 by default). Select the single line mask (hold down on mask tool to see the toolbar flyout. Select the third button from the left) and create a mask somewhere in the channel. Fill the mask with white (Edit/Fill - Contetnts white, opacity 100%, mode: Normal).
Step 2: Now select the rectangle mask tool and double click the button to open the tool properties. From Style select Fixed size and enter width of your image under Width and under Height enter 2. Now select the white line with 300×2 pixel mask and create a patern (Edit/Define pattern). Deselect and fill the whole channel with pattern you just created (Edit/Fill - Contents White, Opacity 100%, Mode Normal).
Step 3: Your channel should look something like this. If it does, switch back to layer view, if it doesn't... hm, keep trying :-). Create a new layer and set the Opacity to 40% or 50% (depends on your choice). Load the selection (Select/Load selection) of the channel you created (or tried to create :-), it should be called Alpha 1, unless you messed around with name of the channel.
Make sure that your active layer is the emptyone you created earlier and fill the selection with black (Edit/Fill - Contents Black, Opacity 100%, Mode Normal.
Thats it. Try some different opacity levels for the layer to control the visibility of scanlines.
