How to vectorize illustrations with Inkscape

- Open bitmap image with Inkscape; select embed
- Select all (Ctrl+A)
- Path->Trace Bitmap (Shift+Alt+B)
- Select Brightness cutoff; deselect Smooth; press OK (ignore the preview; it doesn't work)
- Object->Lower to Bottom (End) to move the vectorized image behind the bitmap image
- Click the bitmap image to select it
- Press Delete to delete the bitmap image leaving only the vectorized image
- Right-click on vectorized image; select Enter group
- Click on background; delete the (white) background; now the background of the SVG is transparent
- Select all (Ctrl+A)
- Path->Simplify (Ctrl+L) (with Simplification threshold 0.0005; see Preferences/Misc)
- Save as PDF (without Export area is drawing/page) and Compressed Inkscape SVG