^ what he said,
assuming you're using ps
make a new image
make it small like 4x4 pixels
make the background transparent
zoom in
use a 1 pixel pencil
make a black diagonal line from 1 corner to the next
click edit->define pattern
define it as whatever
goto your file you want to have the diagonal lines
click the paint bucket tool
at the top where it says foreground in the dropdown menu, select pattern
find your pattern
use the paint bucket over the image
you can make different patterns or change the direction etc, or make it thicker by making the canvas bigger and making the line thicker than 1 pixel
thats how its done, if you know your way around ps you should have no problem doing that
This post was edited by archon210 on Nov 5 2009 06:11pm