Open CV library In Python

1. OpenCV In Python
Kaizen Group presentation
Jun 2023

2. Why AI?
Conditions ….
For example:
X<100
-10<Y <20

3. Table of contents
• Introduction
• Drawing shapes and lines
• Simple & Logical operations on images
• Threshold & Watermark
• Morphologic transformations
• Edge & Corner Detection

4. Table of contents
• Object recognition with Template & Feature Matching
• Histogram of images
• Color spaces (RGB, BGR, HSV)
• Video and Color detection
• Video – Face detection
• Video – Hand gesture Detection

5. Drawing shapes and lines
import cv2
import numpy as np
#creating a black square
image=np.zeros((512,512,3),np.uint8)
#we can also create this in black and white,however there would not be any changes
image_bw=np.zeros((512,512),np.uint8)
cv2.imshow("black rectangle(color)",image)
cv2.imshow("black rectangle(B&W)",image_bw)

6. • #create a line over black square
• #cv2.line(image, starting coordinates, ending coordinates, color, thickness)
• #drawing a diagonal line of thickness 6 pixels
• image=np.zeros((512,512,3),np.uint8)
• cv2.line(image,(0,0),(511,511),(255,127,0),6)
• cv2.imshow("blue line",image)
Drawing shapes and lines

7. • #create a rectangle over a black square
• #cv2.rectangle(image,starting coordinates, ending coordinates,
color, thickness)
• #drawing a rectangle of thickness 5 pixels
• image=np.zeros((512,512,3),np.uint8)
• cv2.rectangle(image,(30,50),(100,150),(255,127,0),5)
• cv2.imshow("rectangle",image)
Drawing shapes and lines

8. • #creating a circle over a black square
• #cv2.circle(image,center,radius,color,fill)
• image=np.zeros((512,512,3),np.uint8)
• cv2.circle(image,(100,100),(50),(255,127,0),-1)
• cv2.imshow("circle",image)
Drawing shapes and lines

9. • #creating a polygon
• image=np.zeros((512,512,3),np.uint8)
• #lets define four points
• pts=np.array([[10,50], [400,60], [30,89], [90,68]], np.int32)
• #lets now reshape our points in form required by polylines
• pts=pts.reshape((-1,1,2))
• cv2.polylines(image, [pts], True, (0,255,255), 3)
• cv2.imshow("polygon",image)
Drawing shapes and lines

10. • #putting text using opencv
• #cv2.putText(image,'text to display',bootom left starting point, font,font
size, color, thickness)
• image=np.zeros((512,512,3),np.uint8)
• cv2.putText(image,"hello world", (75,290),
cv2.FONT_HERSHEY_COMPLEX,2,(100,170,0),3)
• cv2.imshow("hello world",image)
• cv2.waitKey(0)
• cv2.destroyAllWindows()
Drawing shapes and lines
hello world

11. Simple & Logical operations on images
• img = cv.imread ("/content/drive/MyDrive/totfarangi.jpg", cv.IMREAD_COLOR)
• # Show the image
• cv2_imshow(img)
• cv.waitKey(0)
• cv.destroyAllWindows()
• img.shape (524, 650, 3)
• red_Strawberry = img [240:500 , 50:320 ]
• cv2_imshow(red_Strawberry)
• cv.waitKey(0)
• cv.destroyAllWindows()

12. Logical operations on images
• ret, maskimg = cv.threshold(img2gray, 40 ,255, cv.THRESH_BINARY)
• mask_inv = cv.bitwise_not(maskimg)
•
cv2_imshow(mask_inv)
• cv2.waitKey(0)
• cv2.destroyAllWindows()

13. • img1_m = cv.bitwise_and(img1, img2, mask=maskimg)
•
cv2_imshow(img1_m)
• cv2.waitKey(0)
• cv2.destroyAllWindows()
Logical operations on images

14. Color spaces
BGR, RGB , HSV
• #BGR
• image_bgr = cv.imread('/content/drive/MyDrive/totfarangi.jpg')
• image_gr = cv.cvtColor(image_bgr, cv.COLOR_BGR2GRAY)
• cv2_imshow(image_bgr)
• cv2_imshow(image_gr)
• cv2.waitKey(0)
• cv2.destroyAllWindows()

15. • # RGB
• #blue_ch, green_ch, red_ch = cv.split(image)
• image_rgb = cv.cvtColor(image_bgr, cv.COLOR_BGR2RGB)
• # BGR opencv
• # BGRA / RGBA 4 channel alpha opacity
• cv2_imshow(image_rgb)
• cv2.waitKey(0)
• cv2.destroyAllWindows()
Color spaces

16. • # HSV [20, 100, 100]
• image_hsv = cv.cvtColor(image_bgr, cv.COLOR_BGR2HSV)
• cv2_imshow(image_hsv)
• cv2.waitKey(0)
• cv2.destroyAllWindows()
• plt.imshow(image_hsv)
• plt.show()
Color spaces