add new opencv programe files and some sample test images

Author: manthan89-py

Find_and_draw_contours_using_opencv.py

@@ -0,0 +1,20 @@
+import cv2
+import numpy as np
+
+img = cv2.imread('test_images/opencv-logo.png')
+imggray = cv2.cvtColor(img , cv2.COLOR_BGR2GRAY)
+ret , threshold = cv2.threshold(imggray , 127 , 255 ,0)
+
+# contours : numpy array of (x,y) coordinates of boundries of object.
+# heirarchy : information about image topology
+contours , heirarchy = cv2.findContours(threshold , cv2.RETR_TREE , cv2.CHAIN_APPROX_NONE)
+
+print(f"Number of Contours : {str(contours)}")
+
+# contourIdx = -1 i.e draw all contours
+cv2.drawContours(img , contours , -1 , (0,255,0) , 5)
+
+cv2.imshow("Original Image",img)
+cv2.imshow("Gray image",imggray)
+cv2.waitKey(0)
+cv2.destroyAllWindows()

Readme.md

@@ -22,6 +22,9 @@
 * image_gradients.py
 * canny_edge_detection.py
 * image_pyramids_opencv.py
+* image_blending_using_pyramids_opencv.py
+* Find_and_draw_contours_using_opencv.py
+* basic_motion_detection_using_opencv.py
 
 ## Helpful Documentations⭐:
 * OpenCV : https://docs.opencv.org/master/

basic_motion_detection_using_opencv.py

@@ -0,0 +1,52 @@
+import cv2
+import numpy as np
+
+cap = cv2.VideoCapture('test_images/vtest.avi')
+
+ret , frame1 = cap.read()
+ret , frame2 = cap.read()
+while cap.isOpened():
+
+# difference between first and second frame
+diff = cv2.absdiff(frame1,frame2)
+
+# convert it into gray ( for finding contours )
+gray = cv2.cvtColor(diff , cv2.COLOR_BGR2GRAY)
+
+# apply blur
+blur = cv2.GaussianBlur(gray , (5,5) , 0)
+
+# find threshold
+_ , th = cv2.threshold(blur , 20 , 255 , cv2.THRESH_BINARY)
+
+# dilate the images
+dilated = cv2.dilate(th, None , iterations=3)
+
+# find contours
+contours , _ = cv2.findContours(dilated , cv2.RETR_TREE , cv2.CHAIN_APPROX_SIMPLE)
+
+# draw contours
+# cv2.drawContours(frame1 , contours , -1 , (0,255,0) , 3)
+
+# Make rectangle around contours
+for contour in contours:
+(x,y,w,h) = cv2.boundingRect(contour)
+
+if cv2.contourArea(contour) < 900:
+continue
+
+cv2.rectangle(frame1 ,(x,y) , (x+w,y+h) , (0,255,0) , 2)
+cv2.putText(frame1,'Status: Movement' , (10,40) , cv2.FONT_HERSHEY_SIMPLEX ,1 , (255,0,0), 3)
+
+cv2.imshow('feed' , frame1)
+frame1 = frame2
+ret , frame2 = cap.read()
+
+# again read the frame for only second frame2
+# that's how we calculate the difference between two frames
+
+if cv2.waitKey(40) == 27:
+break
+
+cap.release()
+cv2.destroyAllWindows()

image_blending_using_pyramids_opencv.py

@@ -0,0 +1,84 @@
+import cv2
+import numpy as np
+
+apple = cv2.imread('test_images/apple.jpg')
+orange = cv2.imread('test_images/orange.jpg')
+
+# print(apple.shape)
+# print(orange.shape)
+
+# apple_orange = np.hstack((apple[: , :256] ,orange[: , 256:]))
+
+
+
+# Gaussian pyramid for apple image
+apple_copy = apple.copy()
+
+gp_apple = [apple_copy]
+
+for i in range(6):
+apple_copy = cv2.pyrDown(apple_copy)
+gp_apple.append(apple_copy)
+
+# Gaussian pyramid for Orange image
+orange_copy = orange.copy()
+
+gp_orange = [orange_copy]
+
+for i in range(6):
+orange_copy = cv2.pyrDown(orange_copy)
+gp_orange.append(orange_copy)
+
+
+
+
+
+# Generate Laplacian pyramid for apple
+apple_copy = gp_apple[5]
+lp_apple = [apple_copy]
+
+for i in range(5,0,-1):
+gaussian_extended = cv2.pyrUp(gp_apple[i])
+laplacian = cv2.subtract(gp_apple[i-1],gaussian_extended)
+lp_apple.append(laplacian)
+
+
+# Generate Laplacian pyramid for orange
+orange_copy = gp_orange[5]
+lp_orange = [orange_copy]
+
+for i in range(5,0,-1):
+gaussian_extended = cv2.pyrUp(gp_orange[i])
+laplacian = cv2.subtract(gp_orange[i-1],gaussian_extended)
+lp_orange.append(laplacian)
+
+
+
+
+
+# Now add left and right halvas of images in each level.
+apple_orange_pyramid = []
+n = 0
+for apple_lap , orange_lap in zip(lp_apple, lp_orange):
+n += 1
+rows , cols , ch = apple_lap.shape
+laplacian = np.hstack((apple_lap[: , 0:int(cols/2)] ,orange_lap[: , int(cols/2):]))
+apple_orange_pyramid.append(laplacian)
+
+
+
+
+
+# Now Reconsturct the image
+apple_orange_reconstruct = apple_orange_pyramid[0]
+for i in range(1,6):
+apple_orange_reconstruct = cv2.pyrUp(apple_orange_reconstruct)
+apple_orange_reconstruct = cv2.add(apple_orange_pyramid[i] , apple_orange_reconstruct)
+
+
+cv2.imshow('apple',apple)
+cv2.imshow('orange',orange)
+cv2.imshow('apple_orange_reconstruct',apple_orange_reconstruct)
+
+cv2.waitKey(0)
+cv2.destroyAllWindows()