Optional lineOptional maxMaximal level for drawn contours. If it is 0, only the specified contour is drawn. If it is 1, the function draws the contour(s) and all the nested contours. If it is 2, the function draws the contours, all the nested contours, all the nested-to-nested contours, and so on. This parameter is only taken into account when there is hierarchy available.
Optional offsetOptional contour shift parameter. Shift all the drawn contours by the specified offset=(dx,dy) .
Optional thicknessThickness of lines the contours are drawn with. If it is negative (for example, thickness=FILLED ), the contour interiors are drawn.
Line connectivity. See LineTypes