def contours2(img):
# equalize Y channel hist
# img = Preprocess.equalizeHistYChannel(img)
# remove artifacts
# img = Preprocess.removeArtifact(img)
# remove RGB artifact
img = Preprocess.removeArtifactYUV(img)
# apply OTSU threshold
ret, thresh = Preprocess.OTSUThreshold(img)
# search for contours and select the biggest one
c, contours, hierarchy = cv2.findContours(thresh, cv2.RETR_TREE,
cv2.CHAIN_APPROX_NONE)
cnt = max(contours, key=cv2.contourArea)
return cnt
