Вы искали: cvsaveimage (Английский - Русский)

cvsaveimage(filename, frame);
cvsaveimage(filename, frame);

cvsaveimage("out.jpg", imgout);
cvsaveimage("out.jpg", imgout);

cvsaveimage("image.jpg",frame);
cvsaveimage("image.jpg",frame);

cvsaveimage() , а для С++ cv::imwrite()
cvsaveimage() , а для С++ cv::imwrite()

cvsaveimage("image16-canny.png", canny);
cvsaveimage("image16-canny.png", canny);

cvsaveimage(filename, frame);cvsaveimage(filename, dst);
cvsaveimage(filename, frame);cvsaveimage(filename, dst);