Convert video to gray scale using OpenCV¶

In [1]:

import cv2
from IPython.display import HTML
from scripts.jupyter.helpers import play_video

In [2]:

# Download some sample movie
!wget -nc -nv http://techslides.com/demos/sample-videos/small.mp4 -P ../downloads

2018-12-31 12:23:42 URL:http://techslides.com/demos/sample-videos/small.mp4 [383631/383631] -> "../downloads/small.mp4" [1]

In [3]:

# Let's play it
play_video('downloads/small.mp4')

Out[3]:

In [4]:

# Load the video with OpenCV and check it's properties
cap = cv2.VideoCapture('downloads/small.mp4')
width = int(cap.get(cv2.CAP_PROP_FRAME_WIDTH))
height = int(cap.get(cv2.CAP_PROP_FRAME_HEIGHT))
fps = int(cap.get(cv2.CAP_PROP_FPS))
print("Width={} Height={} FPS={}".format(width, height, fps))

Width=560 Height=320 FPS=30

In [5]:

# Convert video to grayscale and save it to file

# Seek to first frame in input video
cap.set(cv2.CAP_PROP_POS_FRAMES, 0)

# Open video writer
vid = cv2.VideoWriter('../output/small_bw.mp4',
                      cv2.VideoWriter_fourcc(*'H264'),
                      fps,
                      (width, height),
                      isColor=False)

# Initialize number of frames counter
frames_count = 0

while(True):
    ret, frame = cap.read()
    frames_count += 1 if ret else 0
    if ret:
        # Convert frame from color to grayscale and write it
        frame_bw = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)
        vid.write(frame_bw)
    else:
        vid.release()
        break

print("Processed {} frames".format(frames_count))

Processed 166 frames

In [6]:

# Check the result
play_video('output/small_bw.mp4')

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