**Photoshop, should work with any version, and hopefuly this can translate to Gimp
So, I've been thinking on this ever since I tried Ascension's tutorial, and read through the big discussion about how to get the rings around the land to look more hand and less straight-edgey-cornerish in the antique style maps. My solution was to use an out glow with a gradient, and hide the imperfections with a woodcut style layer over top. nice enough effect, i suppose, but the thing that's been bothering me for quite some time (from other projects I've been working on as well) was that i KNOW there is a way to get gradients to follow the shape of an object (or path, as it were). Typically, gradient fills go the entire shape, up/down, left/right, radial, diamond, etc - straight directions and that's it. But what if we want to have one follow the coastline?
So i got to experimenting and stumbled upon a rather nifty ring effect using the Stroke layer effect, of all things - the result is like so:
I set up a gradient with the following pattern:
I set up the far left with 5% opacity at position 0%.
Next is 0% opacity at position 5%
Then 10% opacity at position 10%
0% at 15, 20% at 20%
and so on - you should start to see the pattern now. I found it easiest to set up all my 0% opacities at each 5% mark first, then add in the opacity markers afterwards. i also used the keyboard for typing the numbers in instead of eyeballing it Note I started at 5% and end with transparency right next to the coastline - if you end at 100% opaque you will lose the coastline detail. ( I breifly experimented with setting extra markers to sharply define the lines, but it wasn't a noticeable enough difference to make it worth the hassle)
I used the following settings in the Stroke style editor itself: (note, shapeburst is our friend - and the key to this entire process.)
You can also get some neat effects by switching position to inner, or even Center.
I have this gradient set as black to black in the gradient editor, but you can of course modify the colours with the bottom set of sliders all you want, that can give some nice sepia or rainbow tones if you're not using another method of adjusting the colour..
I find that the rings look best between 30 and 75 - too much smaller and it just looks like a greyscale stroke, much larger and it starts looking artificial again.
You can also use the same technique with standard gradients to simply have the gradient follow the lines/shapes you are using, without the rings - this could make for some easy beaches around lakes