Save multiple images with OpenCV and Python

Question

I'm using OpenCV and Python to take images. However currently I can only take one picture at a time. I would like to have OpenCV to take multiple pictures. This is my current code.

import cv2.cv as cv
import time

cv.NamedWindow("camera", 1)

capture = cv.CaptureFromCAM(0)

while True:
    img = cv.QueryFrame(capture)
    cv.ShowImage("camera", img)
    cv.SaveImage('pic.jpg', img)
    if cv.WaitKey(10) == 27:
        break 

Solution 1

Your code overwrite a file. Save to different file each time. For example:

import cv2.cv as cv
import time

cv.NamedWindow("camera", 1)

capture = cv.CaptureFromCAM(0)

i = 0
while True:
    img = cv.QueryFrame(capture)
    cv.ShowImage("camera", img)
    cv.SaveImage('pic{:>05}.jpg'.format(i), img)
    if cv.WaitKey(10) == 27:
        break
    i += 1

Solution 2

A minimal example of what you'd like to do, based on the c++ binded interface.

import cv2

cpt = 0
maxFrames = 5 # if you want 5 frames only.

try:
    vidStream = cv2.VideoCapture(0) # index of your camera
except:
    print "problem opening input stream"
    sys.exit(1)

while cpt < maxFrames:
    ret, frame = vidStream.read() # read frame and return code.
    if not ret: # if return code is bad, abort.
        sys.exit(0)
    cv2.imshow("test window", frame) # show image in window
    cv2.imwrite("image%04i.jpg" %cpt, frame)
    cpt += 1

A full example of script, able to read from a camera index, or a file. Includes some failsafes and some information about read device.

usage: record.py [source] [target folder]

#!/usr/bin/env python
import cv2
import sys
import os

cpt = 0
maxFrames = 30

try:
    targetDir = sys.argv[2]
except:
    targetDir = "" # if no argument, then use current directory

try: # read input. eval if to transform video index to int
    vidStream = cv2.VideoCapture(eval(sys.argv[1]))
except:
    print "problem opening input stream"
    sys.exit(1)
if not vidStream.isOpened():
    print "capture stream not open"
    sys.exit(1)

# informations in case the input is a video file.
nFrames = vidStream.get(cv2.cv.CV_CAP_PROP_FRAME_COUNT)
print "frame number: %s" %nFrames
fps = vidStream.get(cv2.cv.CV_CAP_PROP_FPS)
print "FPS value: %s" %fps

# note that we could use frame number here, or "while 1"
# so we could read from a live written file or capture devide.
while cpt < maxFrames:
    ret, frame = vidStream.read() # read frame and return code.
    if not ret:
        print "end of stream"
        sys.exit(0)
    cv2.imshow("test window", frame) # show image in window
    cv2.imwrite(os.path.join(targetDir, "image_%04i.jpg" %cpt), frame)
    cpt += 1
    keyPressed = cv2.waitKey(1) # time to wait between frames
    if keyPressed != -1: # if user pressed a key, stop recording.
        sys.exit(0)

Solution 3

change the name of the image to be saved to " [image name] [a number which increase after every loop] " By doing this your image will be stored with a new name after every loop.. otherwise all the images will overwrite the same name !

import cv2.cv as cv
import time

cv.NamedWindow("camera", 1)

capture = cv.CaptureFromCAM(0)
num = 0
while True:
    img = cv.QueryFrame(capture)
    cv.ShowImage("camera", img)
    cv.SaveImage('pic'+str(num)+'.jpg', img)
    if cv.WaitKey(10) == 27:
        break
    num += 1

now your images will be saved as pic0.jpg, pic1.jpg, pic2.jpg and so on..

Solution 4

i think this wil helpful...

import cv2

vid = cv2.VideoCapture("video.mp4")
d = 0
ret, frame = vid.read()

while ret:
    ret, frame = vid.read()
    filename = "images/file_%d.jpg"%d
    cv2.imwrite(filename, frame)
    d+=1

this will save every frame with different name.

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