splitting UV islands to have each face separated by small amount Please note that I am still a beginner.

I have seams and UVs aligned so that the default Blender color texture looks perfect on my low-poly model. When I bake normal maps from higher res models (texture not high-res), I see seams on the borders of faces leaking onto the nearby faces (within the bounds of their island) and this creates very obvious seams when looking at the model with normal map. I though the solution to this would be to scale all UVs but without any face changing size -- to separate them by a small amount.

Is there a script for this or maybe another solution to the problem visible below?



This is my model with normal maps, created in Blender and seen here in 3DCoat.



This is my current UV layout.
Margin

In order to create a small gap between the UV islands you can use the Margin factor it is shown in the tool options panel while performing most of the UV mapping related operations (Unwrap, Smart Unwrap, Lightmap,...)  or even in the Pack Islands command.



This will create an uniform margin along the island's boundaries. That's probably the supposed way to achieve the result that fit best the baking-with-margins workflow.

Scale islands individually

If you are not interested in a uniform margin, but you just need to scale each face down, there is the possibility to change the scaling (S) pivot as shown in the image sequence below: