Update calcBackProject_Demo1.py

To round a ndarray it's necessary to use np.round() instead to Built-in Python round()

samples/python/tutorial_code/Histograms_Matching/back_projection/calcBackProject_Demo1.py

@@ -31,7 +31,7 @@ def Hist_and_Backproj(val):
     histImg = np.zeros((h, w, 3), dtype=np.uint8)
 
     for i in range(bins):
-        cv.rectangle(histImg, (i*bin_w, h), ( (i+1)*bin_w, h - int(round( hist[i]*h/255.0 )) ), (0, 0, 255), cv.FILLED)
+        cv.rectangle(histImg, (i*bin_w, h), ( (i+1)*bin_w, h - int(np.round( hist[i]*h/255.0 )) ), (0, 0, 255), cv.FILLED)
 
     cv.imshow('Histogram', histImg)
     ## [Draw the histogram]