distortion : freebies : tutorials : groove effect

		Open the image you want to add grooves to.
		Choose Image > Adjust > Levels and in the middle input level box type 0.4 Move the marquee up one pixel. You can do this by using the arrow keys. Again choose Levels from the image menu and enter 2.0 in the middle input box.
		Move the marquee. That's it.. To do more just follow step 2. To make the grooves inverted just type in the values the other way round (2.0 first)