Python how to capture image from webcam on click using OpenCV

Question

I want to capture and save a number of images from my webcam using OpenCV  This is my code currently   import cv2  camera   cv2 VideoCapture 0  for i in range 10       return value  image   camera read       cv2 imwrite  opencv  str i    png   image  del camera    The problem with this is that I do not know when the images are being taken  so a lot of them end up blurry  My question is  Is there a way to have the image taken on the click of a keyboard key    Also is there a better way to take multiple images  instead of range

User · Answer

i m not too experienced with open cv but if you want the code in the for loop to be called when a key is pressed  you can use a while loop and an raw input and a condition to prevent the loop from executing forever  import cv2  camera   cv2 VideoCapture 0  i   0 while i  lt  10      raw input  Press Enter to capture       return value  image   camera read       cv2 imwrite  opencv  str i    png   image      i    1 del camera

User · Answer

Here is a simple programe to capture a image from using laptop default camera I hope that this will be very easy method for all   import cv2    1 creating a video object video   cv2 VideoCapture 0     2  Variable a   0   3  While loop while True      a   a   1       4 Create a frame object     check  frame   video read         Converting to grayscale      gray   cv2 cvtColor frame cv2 COLOR BGR2GRAY        5 show the frame      cv2 imshow  Capturing  frame        6 for playing      key   cv2 waitKey 1      if key    ord  q            break   7  image saving showPic   cv2 imwrite  filename jpg  frame  print showPic    8  shutdown the camera video release   cv2 destroyAllWindows    You can see my github code here

User · Answer

Breaking down your code example  Explanations are under the line of code    import cv2   imports openCV for usage  camera   cv2 VideoCapture 0    creates an object called camera  of type openCV video capture  using the first camera in the list of cameras connected to the computer   for i in range 10     tells the program to loop the following indented code 10 times      return value  image   camera read     read values from the camera object  using it s read method  it resonds with 2 values save the 2 data values into two temporary variables called  return value  and  image       cv2 imwrite  opencv  str i    png   image    use the openCV method imwrite  that writes an image to a disk  and write an image using the data in the temporary data variable  fewer indents means that the loop has now ended     del camera    deletes the camrea object  we no longer needs it   you can what you request in many ways  one could be to replace the for loop with a while loop   running forever  instead of 10 times   and then wait for a keypress   like answered by danidee while I was typing   or create a much more evil service that hides in the background and captures an image everytime someone presses the keyboard

User · Answer

This is a simple program to capture an image from using a default camera  Also  It can Detect a human face   import cv2 import sys import logging as log import datetime as dt from time import sleep  cascPath    haarcascade frontalface default xml  faceCascade   cv2 CascadeClassifier cascPath  log basicConfig filename  webcam log  level log INFO   video capture   cv2 VideoCapture 0  anterior   0  while True      if not video capture isOpened            print  Unable to load camera            sleep 5          pass        Capture frame-by-frame     ret  frame   video capture read        gray   cv2 cvtColor frame  cv2 COLOR BGR2GRAY       faces   faceCascade detectMultiScale          gray          scaleFactor 1 1          minNeighbors 5          minSize  30  30               Draw a rectangle around the faces     for  x  y  w  h  in faces          cv2 rectangle frame   x  y    x w  y h    0  255  0   2       if anterior    len faces           anterior   len faces          log info  faces    str len faces     at   str dt datetime now             Display the resulting frame     cv2 imshow  Video   frame       if cv2 waitKey 1   amp  0xFF    ord  s              check  frame   video capture read           cv2 imshow  Capturing   frame          cv2 imwrite filename  saved img jpg   img frame          video capture release           img new   cv2 imread  saved img jpg   cv2 IMREAD GRAYSCALE          img new   cv2 imshow  Captured Image   img new          cv2 waitKey 1650          print  Image Saved           print  Program End           cv2 destroyAllWindows            break     elif cv2 waitKey 1   amp  0xFF    ord  q            print  Turning off camera            video capture release           print  Camera off            print  Program ended            cv2 destroyAllWindows           break        Display the resulting frame     cv2 imshow  Video   frame     When everything is done  release the capture video capture release   cv2 destroyAllWindows     output    Also  You can check out my GitHub code

User · Answer

Here is a simple program that displays the camera feed in a cv2 namedWindow and will take a snapshot when you hit SPACE   It will also quit if you hit ESC   import cv2  cam   cv2 VideoCapture 0   cv2 namedWindow  test    img counter   0  while True      ret  frame   cam read       if not ret          print  failed to grab frame           break     cv2 imshow  test   frame       k   cv2 waitKey 1      if k 256    27            ESC pressed         print  Escape hit  closing              break     elif k 256    32            SPACE pressed         img name    opencv frame    png  format img counter          cv2 imwrite img name  frame          print     written   format img name           img counter    1  cam release    cv2 destroyAllWindows     I think this should answer your question for the most part   If there is any line of it that you don t understand let me know and I ll add comments   If you need to grab multiple images per press of the SPACE key  you will need an inner loop or perhaps just make a function that grabs a certain number of images   Note that the key events are from the cv2 namedWindow so it has to have focus

[python] Python: how to capture image from webcam on click using OpenCV

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