Drawing functions added

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Yogesh Ojha 2018-10-06 22:19:52 +05:30 committed by GitHub
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--- ---
language: c++/python language: python
filename: learnopencv.py filename: learnopencv.py
contributors: contributors:
- ["Yogesh Ojha", "http://github.com/yogeshojha"] - ["Yogesh Ojha", "http://github.com/yogeshojha"]
@ -23,11 +23,11 @@ https://medium.com/@nuwanprabhath/installing-opencv-in-macos-high-sierra-for-pyt
### Here we will be focusing on python implementation of OpenCV ### Here we will be focusing on python implementation of OpenCV
* __Reading image in OpenCV__
``` ```
# Reading image in OpenCV
import cv2 import cv2
img = cv2.imread('cat.jpg') img = cv2.imread('cat.jpg')
# Simple isn't it?
# Displaying the image # Displaying the image
# imshow() function is used to display the image # imshow() function is used to display the image
cv2.imshow('Image',img) cv2.imshow('Image',img)
@ -35,10 +35,67 @@ cv2.imshow('Image',img)
# If you are getting error, Object Type None, your image path may be wrong. Please recheck the pack to the image # If you are getting error, Object Type None, your image path may be wrong. Please recheck the pack to the image
cv2.waitKey(0) cv2.waitKey(0)
# waitKey() is a keyboard binding function and takes arguement in milliseconds. For GUI events you MUST use waitKey() function. # waitKey() is a keyboard binding function and takes arguement in milliseconds. For GUI events you MUST use waitKey() function.
# Writing an image
cv2.imwrite('catgray.png',img)
# first arguement is the file name and second is the image
# Convert image to grayscale
gray_image = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
# Capturing Video from Webcam
cap = cv2.VideoCapture(0)
#0 is your camera, if you have multiple camera, you need to enter their id
while(True):
# Capturing frame-by-frame
_, frame = cap.read()
cv2.imshow('Frame',frame)
# When user presses q -> quit
if cv2.waitKey(1) & 0xFF == ord('q'):
break
# Camera must be released
cap.release()
# Playing Video from file
cap = cv2.VideoCapture('movie.mp4')
while(cap.isOpened()):
_, frame = cap.read()
# Play the video in grayscale
gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)
cv2.imshow('frame',gray)
if cv2.waitKey(1) & 0xFF == ord('q'):
break
cap.release()
# Drawing The Line in OpenCV
# cv2.line(img,(x,y),(x1,y1),(color->r,g,b->0 to 255),thickness)
cv2.line(img,(0,0),(511,511),(255,0,0),5)
# Drawing Rectangle
# cv2.rectangle(img,(x,y),(x1,y1),(color->r,g,b->0 to 255),thickness)
# thickness = -1 used for filling the rectangle
cv2.rectangle(img,(384,0),(510,128),(0,255,0),3)
# Drawing Circle
cv2.circle(img,(xCenter,yCenter), radius, (color->r,g,b->0 to 255), thickness)
cv2.circle(img,(200,90), 100, (0,0,255), -1)
# Drawing Ellipse
cv2.ellipse(img,(256,256),(100,50),0,0,180,255,-1)
# Adding Text On Images
cv2.putText(img,"Hello World!!!", (x,y), cv2.FONT_HERSHEY_SIMPLEX, 2, 255)
cv2.destroyAllWindows()
# destroyAllWindows() destroys all windows. If you wish to destroy specific window pass the exact name of window you created.
``` ```
Further Reading: Further Reading:
OpenCV drawing Functions
<https://docs.opencv.org/2.4/modules/core/doc/drawing_functions.html>
An up-to-date language reference can be found at An up-to-date language reference can be found at
<https://opencv.org/> <https://opencv.org/>