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#! /usr/bin/env python
print "OpenCV Python version of contours"
# import the necessary things for OpenCV
import cv2.cv as cv
# some default constants
_SIZE = 500
_DEFAULT_LEVEL = 3
# definition of some colors
_red = (0, 0, 255, 0);
_green = (0, 255, 0, 0);
_white = cv.RealScalar (255)
_black = cv.RealScalar (0)
# the callback on the trackbar, to set the level of contours we want
# to display
def on_trackbar (position):
# create the image for putting in it the founded contours
contours_image = cv.CreateImage ( (_SIZE, _SIZE), 8, 3)
# compute the real level of display, given the current position
levels = position - 3
# initialisation
_contours = contours
if levels <= 0:
# zero or negative value
# => get to the nearest face to make it look more funny
_contours = contours.h_next().h_next().h_next()
# first, clear the image where we will draw contours
cv.SetZero (contours_image)
# draw contours in red and green
cv.DrawContours (contours_image, _contours,
_red, _green,
levels, 3, cv.CV_AA,
(0, 0))
# finally, show the image
cv.ShowImage ("contours", contours_image)
if __name__ == '__main__':
# create the image where we want to display results
image = cv.CreateImage ( (_SIZE, _SIZE), 8, 1)
# start with an empty image
cv.SetZero (image)
# draw the original picture
for i in range (6):
dx = (i % 2) * 250 - 30
dy = (i / 2) * 150
cv.Ellipse (image,
(dx + 150, dy + 100),
(100, 70),
0, 0, 360, _white, -1, 8, 0)
cv.Ellipse (image,
(dx + 115, dy + 70),
(30, 20),
0, 0, 360, _black, -1, 8, 0)
cv.Ellipse (image,
(dx + 185, dy + 70),
(30, 20),
0, 0, 360, _black, -1, 8, 0)
cv.Ellipse (image,
(dx + 115, dy + 70),
(15, 15),
0, 0, 360, _white, -1, 8, 0)
cv.Ellipse (image,
(dx + 185, dy + 70),
(15, 15),
0, 0, 360, _white, -1, 8, 0)
cv.Ellipse (image,
(dx + 115, dy + 70),
(5, 5),
0, 0, 360, _black, -1, 8, 0)
cv.Ellipse (image,
(dx + 185, dy + 70),
(5, 5),
0, 0, 360, _black, -1, 8, 0)
cv.Ellipse (image,
(dx + 150, dy + 100),
(10, 5),
0, 0, 360, _black, -1, 8, 0)
cv.Ellipse (image,
(dx + 150, dy + 150),
(40, 10),
0, 0, 360, _black, -1, 8, 0)
cv.Ellipse (image,
(dx + 27, dy + 100),
(20, 35),
0, 0, 360, _white, -1, 8, 0)
cv.Ellipse (image,
(dx + 273, dy + 100),
(20, 35),
0, 0, 360, _white, -1, 8, 0)
# create window and display the original picture in it
cv.NamedWindow ("image", 1)
cv.ShowImage ("image", image)
# create the storage area
storage = cv.CreateMemStorage (0)
# find the contours
contours = cv.FindContours(image,
storage,
cv.CV_RETR_TREE,
cv.CV_CHAIN_APPROX_SIMPLE,
(0,0))
# comment this out if you do not want approximation
contours = cv.ApproxPoly (contours,
storage,
cv.CV_POLY_APPROX_DP, 3, 1)
# create the window for the contours
cv.NamedWindow ("contours", 1)
# create the trackbar, to enable the change of the displayed level
cv.CreateTrackbar ("levels+3", "contours", 3, 7, on_trackbar)
# call one time the callback, so we will have the 1st display done
on_trackbar (_DEFAULT_LEVEL)
# wait a key pressed to end
cv.WaitKey (0)
cv.DestroyAllWindows()
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