2 down vote

The functions cv2.drawMatches and cv2.drawMatchesKnn are not available in newer versions of OpenCV 2.4. @rayryeng provided a lightweight alternative which works as is for the output of DescriptorMatcher.match. The difference with DescriptorMatcher.knnMatch is that the matches are returned as a list of lists. To use the @rayryeng alternative, the matches must be extracted into a 1-D list.

For example, the Brute-Force Matching with SIFT Descriptors and Ratio Test tutorial could be amended as such:

# BFMatcher with default params

bf = cv2.BFMatcher()

matches = bf.knnMatch(des1,des2, k=2)

# Apply ratio test

good = []

for m,n in matches:

    if m.distance < 0.75*n.distance:

       # Removed the brackets around m

       good.append(m)

# Invoke @rayryeng's drawMatches alternative, note it requires grayscale images

gray1 = cv2.cvtColor(img1,cv2.COLOR_BGR2GRAY)

gray2 = cv2.cvtColor(img2,cv2.COLOR_BGR2GRAY)

drawMatches(gray1,kp1,gray2,kp2,good)