NoFontNL

Hello all, Let's say I have the black of this image selected. (source: https://www.seekpng.com/ipng/u2w7u2q8t4y3q8y3_by-chuloc-on-deviantart-cute-anime-line-art/) Now I want to select all the inside areas, without doing Ctrl + Manually select new area. How do I achieve that? I was thinking about something like a magic wand tool which is not based on color, but is based on whether pixels are selected or not Thanks in advance!