Made some tests with rastering techniques. This one has been rastered in GIMP and then imported to Inkscape where I did Path-Trace. So it is a true vector image although it looks like raster.
甘地（光柵效應）
Dithering、famous-people、History、India、Leader、Mahatma Gandhi、man、Others、Peace、people、Raster Graphics
抖動、著名的人民、歷史、印度、領導、聖雄甘地、人、其他、和平、人、光柵圖形
資料來源：openclipart ( https://openclipart.org/ )