03-02-2019, 10:15 PM
You can just color select the white and apply the blur. The black being unselected, it won't change:
However, on the edges you don't get a black-to-white transition, you get a sharp black to grey step, and then a grey to white transition. This can be changed with curves, by setting the "black point" to that gray value:
However, on the edges you don't get a black-to-white transition, you get a sharp black to grey step, and then a grey to white transition. This can be changed with curves, by setting the "black point" to that gray value: