3

I have an algorithm, which after each iteration creates a matrix. After some operations on matrix it is plotted to the user. if I run program 6 times I will get:

a bunch of images

My goal is to changing image dynamically, like a movie.

I have no idea from which side to start. I found some ways of creating video from images in python and then wrap it in the video player. But it seems to be a bit complicated and it is impossible to see the changes while algorithm is working. Are there any suggestions how to do it?

martineau
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Sergey Vladimirovich
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    you might want to take a look at [this question](https://stackoverflow.com/questions/753190/programmatically-generate-video-or-animated-gif-in-python) – Kevin He Nov 08 '18 at 19:17

2 Answers2

7

You can use FFMPEG

ffmpeg -r 1 -i img%01d.png -vcodec mpeg4 -y movie.mp4

-r 1 is the number of frames/images per second. Increase it to make the video faster.

In Python:

def convert():
    os.system("ffmpeg -r 1 -i img%01d.png -vcodec mpeg4 -y movie.mp4")

Alternatively, you can use ImageIO to generate a GIF. You can set the parameters for duration of each frame.

import imageio
with imageio.get_writer('/path_to_video.gif', mode='I') as writer:
    for filename in filenames:
        image = imageio.imread(filename)
        writer.append_data(image)

Read the manual on website for more detailed instructions.

Or with cv2,

import cv2

img1 = cv2.imread('1.jpg')
img2 = cv2.imread('2.jpg')
img3 = cv2.imread('3.jpg')

height , width , layers =  img1.shape

video = cv2.VideoWriter('video.avi',-1,1,(width,height))

video.write(img1)
video.write(img2)
video.write(img3)

cv2.destroyAllWindows()
video.release()
Aravind Voggu
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    Thanks! I also found another way of dinamically representation of images: https://matplotlib.org/2.1.2/gallery/animation/image_slices_viewer.html – Sergey Vladimirovich Nov 09 '18 at 10:12
1

Video Data Generation code from scratch in Python (use Jupyter):

import numpy as np
import skvideo.io as sk
# creating sample video data
num_vids = 5
num_imgs = 100
img_size = 50
min_object_size = 1
max_object_size = 5
 
for i_vid in range(num_vids):
 imgs = np.zeros((num_imgs, img_size, img_size)) # set background to 0
 vid_name = ‘vid’ + str(i_vid) + ‘.mp4’
 w, h = np.random.randint(min_object_size, max_object_size, size=2)
 x = np.random.randint(0, img_size — w)
 y = np.random.randint(0, img_size — h)
 i_img = 0
 while x>0:
 imgs[i_img, y:y+h, x:x+w] = 255 # set rectangle as foreground
 x = x-1
 i_img = i_img+1
 sk.vwrite(vid_name, imgs.astype(np.uint8))
# play a video
from IPython.display import Video
Video(“vid3.mp4”) # the script & video should be in same folder
SKG
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