opencv/samples/python/chessboard.py

#!/usr/bin/python
import cv2.cv as cv
import sys
import urllib2

if __name__ == "__main__":
    cv.NamedWindow("win")
    if len(sys.argv) > 1:
        filename = sys.argv[1]
        im = cv.LoadImage(filename, cv.CV_LOAD_IMAGE_GRAYSCALE)
        im3 = cv.LoadImage(filename, cv.CV_LOAD_IMAGE_COLOR)
    else:
       try: # try opening local copy of image
            fileName = '../cpp/left01.jpg'
            im = cv.LoadImageM(fileName, False)
            im3 = cv.LoadImageM(fileName, True)
       except: # if local copy cannot be opened, try downloading it
            url = 'http://code.opencv.org/projects/opencv/repository/revisions/master/raw/samples/cpp/left01.jpg'
            filedata = urllib2.urlopen(url).read()
            imagefiledata = cv.CreateMatHeader(1, len(filedata), cv.CV_8UC1)
            cv.SetData(imagefiledata, filedata, len(filedata))
            im = cv.DecodeImageM(imagefiledata, cv.CV_LOAD_IMAGE_GRAYSCALE)
            im3 = cv.DecodeImageM(imagefiledata, cv.CV_LOAD_IMAGE_COLOR)

    chessboard_dim = ( 9, 6 )

    found_all, corners = cv.FindChessboardCorners( im, chessboard_dim )
    print found_all, len(corners)

    cv.DrawChessboardCorners( im3, chessboard_dim, corners, found_all )

    cv.ShowImage("win", im3);
    cv.WaitKey()
    cv.DestroyAllWindows()