Plot curve using OpenCV instead of Matplotlib's plot().

draw_curve.py

# If you have something like this
matplotlib.pyplot.plot(x_values, y_values, color='yellow')

# You can do the same on OpenCV like this
curve = numpy.column_stack((x_values.astype(numpy.int32), y_values.astype(numpy.int32)))
cv2.polylines(image, [curve], False, (0,255,255))

# And if you need to plot more curves just add them as an element to the array of polygonal curves
curve1 = numpy.column_stack((x1.astype(numpy.int32), y1.astype(numpy.int32)))
curve2 = numpy.column_stack((x2.astype(numpy.int32), y2.astype(numpy.int32)))
cv2.polylines(image, [curve1, curve2], False, (0,255,255))

# More information http://docs.opencv.org/2.4/modules/core/doc/drawing_functions.html#polylines