Add python binding and sample for LSD

samples/python2/lsd_lines_extraction.py

@@ -0,0 +1,40 @@
+#!/usr/bin/env python
+
+'''
+This example shows the functionalities of lines extraction finished by LSDDetector class.
+
+USAGE: lsd_lines_extraction.py [<path_to_input_image>]
+'''
+
+import sys
+import cv2 as cv
+
+if __name__ == '__main__':
+    print(__doc__)
+
+    if len(sys.argv) > 1:
+        fname = sys.argv[1]
+    else :
+        fname = '../data/corridor.jpg'
+
+    img = cv.imread(fname)
+
+    if img is None:
+        print('Failed to load image file:', fname)
+        sys.exit(1)
+
+    gray = cv.cvtColor(img, cv.COLOR_BGR2GRAY)
+
+    lsd = cv.line_descriptor_LSDDetector.createLSDDetector()
+
+    lines = lsd.detect(gray, 2, 1)
+    for kl in lines:
+        if kl.octave == 0:
+            # cv.line only accepts integer coordinate
+            pt1 = (int(kl.startPointX), int(kl.startPointY))
+            pt2 = (int(kl.endPointX), int(kl.endPointY))
+            cv.line(img, pt1, pt2, [255, 0, 0], 2)
+
+    cv.imshow('output', img)
+    cv.waitKey(0)
+    cv.destroyAllWindows()