Thinning outlines of a raster file

This is a basic paint question - sorry for the ignorance. I sometimes need to thin the outlines of a simple raster file. How do I do this.

  • What you need to do is save as and rename the file saving the original, then create a mask with no transparency or feathering from each color. If you want a 2 pixel reduction in the black line copy the mask content, paste as a new object and (since the objects meet 1/2 the reduction) enlarge the object 1 pixel proportionally. Then combine the objects