This tutorial is available as a PDF. Click here to view or download it
Well here's a tutorial adapted from a Photoshop's tutorial and as you've probably guessed we're going to make a map...
EDIT: There are now two ways for doing step 3, thanks to @PeaceHeather.
Below are links to the effects mentioned in this tutorial: Threshold by @Ed Harvey Multi-Threshold by @dpy Curves+ and Gradient Mapping by @pyrochild Grid / Checkerboard by @BoltBait Lines/Grid by @ReMake
Here's the final product:
Open up a new image 800x600 px (File => New).
Apply Clouds effect (Effects => Render => Clouds) and set Scale amount to 545.
Step 3 Way 1
Apply Posterize adjustment (Adjustments => Posterize), set all values to 2.
Step 3 Way 2
Use the Threshold effect (Effects => Color => Threshold).
Now you move the sliders to add or subtract land/sea.
Addition: There is a few more ways to make a black and white contrast image besides the above in step 3. You can use Brightness / Contrast (Adjustments => Brightness / Contrast) with maximum contrast,
or Levels (Adjustments => Levels) with Input Histogram settings shown below,
or Curves (Adjustments => Curves), or Curves+ (Adjustments => Curves+) with Black & White built-in preset,
or Gradient Mapping (download preset Black and White)
All of the above ways will give you exactly the same results.
You should now have a black and white map looking like this:
Use the Magic Wand tool with the Flood mode set at Global and Tolerance at 0, select the white and delete it.
Addition: You can skip this step using in step 3 Multi-Threshold effect (Effects => Multi-Threshold) with the settings shown below.
Make a new layer below the land and fill it with a dark brown colour (5C4D2B)
Add a Radial Gradient to the dark brown background, the primary colour should be AB9E67 and the secondary colour should be 5C4D2B.
If you wish you could hide the map layer.
Now, if you have hidden the map layer, unhide it then select it. Select the Paint Bucket tool, set the Flood mode to Global and fill the black with dark brown colour 2A2415. You should now have something like this:
Step 8 (optional)
Create a new layer which should be on top of all layers and add a compass. If you need a compass image, open the image shown below in Paint.NET and invert its colors (Ctrl+Shift+I). Make sure it's only white and transparent.
Put the compass at the bottom right and set the layers opacity to 100. Merge layers down.
Make a new layer . Change your primary colour to AB9E67 and the secondary colour to 5C4D2B.
Now go to Clouds effect (Effects => Render => Clouds) and set Scale amount to 280.
Now change the Layer Blending Mode to Color Dodge and set Opacity to 75. Merge layers down.
Set your primary colour to Black . Make a new layer . Run Grid / Checkerboard effect (Effects => Render => Grid / Checkerboard) and use the following settings,
or use Lines/Grid effect (Effects => Render => Lines/Grid) with the settings shown below:
Select the Move Selected Pixels tool and move the grid to the left and up by 1 px. Change the Layer Opacity to 75. Merge layers down.
And you must be finished.
Results of the tutorial may vary, and you can change them according to suit your needs or preferences.
Added and edited by ReMake.