REGISTER_FILTER(COLORLEVELS, colorlevels, vf);
REGISTER_FILTER(COLORMATRIX, colormatrix, vf);
REGISTER_FILTER(COPY, copy, vf);
REGISTER_FILTER(COLORLEVELS, colorlevels, vf);
REGISTER_FILTER(COLORMATRIX, colormatrix, vf);
REGISTER_FILTER(COPY, copy, vf);