I used a filter (color > grayscale) to modify the color scheme of my vector graphic. Now when I export to pdf, Inkscape either (a) rasterizes the filter, so that I no longer have a vector graphic, or (b) removes the filter, so that my old colors come back.
How do I make the filter permanent, i.e. actually change the colors in my vector graphic, without rasterizing?
There is also the grayscale "extension", which actually changes the colors as I want it to, but it does not have the filter's options to modify the influence of the original RGB channels on the resulting brightness.