How can I “apply” a filter permanently without rasterizing?

Question

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.

Answer 1

The problem is that the Greyscale Filter is an SVG filter, and these can't be expanded to vector only. When saved as a PDF, SVG filters must be rasterized because the format doesn't support SVG filters. So the only real option, if you want to keep everything vector, would be to recolour the artwork yourself by changing fill and stroke colours instead of relying on a filter.

There are a couple of possible work-arounds to make the task slightly easier, although manual recolouring will still be required.

1. Make a copy of the original coloured artwork. Apply the Greyscale Filter to it, and use this copy to change the colours of the objects in the original, selecting one at a time, then sampling the colours from the filtered copy using the Pick Colours (eyedropper) tool.

2. Use the Greyscale Extension as a starting point, and from there, manually change the fills and strokes of the objects that aren't the right shades.

Answer 2

No luck. Inkscape's filters do not affect paths nor create new paths which could be separated, they affect the rendering process when the displayed raster image is generated.

Some programs can open as vector a SVG file which is saved in Inkscape and has filters. Illustrator is one of them, but in my tests the shown image has always been different than in Inkscape although Illustrator's appearance panel shows that there's a path with SVG filter. Of course an attempt to "expand" the filter generates a rasterized image.

Path effects can be fixed by converting them to path.

Check if the Extensions have something useful. They affect paths.