I have a map with countries of unique colours, I want to add a 1 pixel thick black border between them, I use gimp is this possible. Alternatively is there a free program I can achieve this in? Thanks for any help!


1 Answer 1


Yes you can make a selection and do Edit > Stroke Selection. Set the stroke to 1px.

Alternatively you can draw paths manually using the Pen Tool, or turn a selection into a path using Select > To Path, do Select > None, and then use Edit > Stroke path. This usually results in smoother lines.

TBH, GIMP isn't ideal for this kind of work, and you may encounter some problems for example if you use Select by Color to make your selections. What actually gets selected might depend on the image. It might also be better to add your strokes to a new layer so that you avoid editing the map layer directly.

Even better in the long run might be to redraw the map using vector software such as Inkscape which is open source and free. Then you can trace over the top of the raster map, deleting it after you've finished, and just add stroke and fill attributes to the vector shapes.

Here's a quick example made in Inkscape. Here I just drew the lines with the pencil tool, with snapping on. Then I used Inkscape's Shape Builder tool to create the individual shape objects, then I added fills, selected everything, then changed the stroke to 1px.

enter image description here

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