added circle detection

Author: NEEHITGOYAL

Python/circle_detection/README.md

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+# Description
+
+A Python Script to detect shapes,shapes area, color,centroid from images.
+
+## How to execute this Script
+
++ Run `pip install opencv-python` to install the required packages.
++ Add the image to same folder with the name **img.jpeg**
++ Run the script using `python3 circle.py`
++ The script will printout circle radius centre coordinates as well as image with same
+ 
+ ## example
+ 
+ ### INPUT
+![](/Python/circle_detection/img.jpeg)
+ ### OUTPUT
+![](/Python/circle_detection/out.png)
+

Python/circle_detection/circle.py

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+#importing libraries required
+import numpy as np
+import cv2 as cv
+#reading image
+img = cv.imread('img.jpeg')
+output = img.copy()
+#converting image to greyscale
+gray = cv.cvtColor(img, cv.COLOR_BGR2GRAY)
+gray = cv.medianBlur(gray, 5)
+#hough circle detection method for circle detection
+circles = cv.HoughCircles(gray, cv.HOUGH_GRADIENT, 1, 20,
+                          param1=50, param2=30, minRadius=0, maxRadius=0)
+#all detected circles 
+detected_circles = np.uint16(np.around(circles))
+# looping on all detected circles to print centroid coordinates and radius
+for (x, y ,r) in detected_circles[0, :]:
+    cv.circle(output, (x, y), r, (0, 0, 0), 3)
+    cv.circle(output, (x, y), 2, (0, 255, 255), 3)
+    print("center x={},y={},radius = {}\n".format(x,y,r))
+
+#showing the output image
+cv.imshow('output',output)
+cv.waitKey(0)
+cv.destroyAllWindows()