add hough line method in Opencv code files

Author: manthan89-py

Readme.md

@@ -28,6 +28,8 @@
 * shape_detection_opencv.py
 * histogram_opencv.py
 * template_matching_opencv.py
+* hough_line_transform_opencv.py
+* probabilistic_hough_line_transform.py
 
 ## Helpful Documentations⭐:
 * OpenCV : https://docs.opencv.org/master/

hough_line_transform_opencv.py

@@ -0,0 +1,39 @@
+import cv2
+import numpy as np
+
+img = cv2.imread('test_images/sudoku.png')
+grey_img = cv2.cvtColor(img , cv2.COLOR_BGR2GRAY)
+
+######## Standard Hough Transform #########
+ 
+# 1 Edge Detection
+edges = cv2.Canny(grey_img , 50 , 150 , apertureSize=3)
+cv2.imshow('canny' , edges)
+
+# 2 Convert lines to Hough lines ( Standard Method )
+lines = cv2.HoughLines(edges, 1 , np.pi / 180 , 200)
+
+
+for line in lines:
+    rho , theta = line[0]
+    a = np.cos(theta)
+    b = np.sin(theta)
+    x0 = a*rho
+    y0 = b*rho
+
+    # x1 stores (r*cos(theta) - 1000*sin(theta))
+    x1 = int(x0 + 1000*(-b))
+    # y1 stores (r*sin(theta) + 1000*(cos(theta)))
+    y1 = int(y0 + 1000*(a))
+    # x2 stores (r*cos(theta) + 1000*sin(theta))
+    x2 = int(x0 - 1000*(-b))
+    # y2 stores (r*sin(theta) - 1000*(cos(theta)))
+    y2 = int(y0 - 1000*(a))
+
+    cv2.line(img , (x1,y1) , (x2,y2) , (0,0,255) , 2)
+
+cv2.imshow('image' , img)
+cv2.waitKey(0)
+cv2.destroyAllWindows()
+
+## Problem : Lines are not perfactly detected.

output/Readme.md

@@ -13,5 +13,5 @@
 # Canny Edge Detection
 <img src="canny_edge_detection.png">
 
-# Approximation Of Geometircal Shapes
+# Approximation Of Geometrical Shapes
 <img src="approximation_of_shapes.png">

probabilistic_hough_line_transform.py

@@ -0,0 +1,20 @@
+import cv2
+import numpy as np
+
+img = cv2.imread('test_images/sudoku.png')
+gray = cv2.cvtColor(img , cv2.COLOR_BGR2GRAY)
+
+# find edges
+canny = cv2.Canny(gray , 50 , 150 , apertureSize=3)
+cv2.imshow("Edges", canny)
+
+# Hough lines Transform ( Probabilistic method )
+lines = cv2.HoughLinesP(canny , 1 , np.pi / 180 , 100 , minLineLength=100 , maxLineGap=10)
+
+for line in lines:
+    x1,y1,x2,y2 = line[0]
+    cv2.line(img , (x1,y1) , (x2,y2) , (0,0,255) , 2)
+
+cv2.imshow("Image",img)
+cv2.waitKey(0)
+cv2.destroyAllWindows()