Creating a movie from binary plots

Hi! So i am trying to create a movie from a loop of binary matrix.

Basically i have a big loop that generates a different binary matrix everytime.

i can use imagesc() to extract frames from every loop cycle but i wonder if I can create a movie combining all the frames from each cycle of the loops?

Many thanks!

[Walter Roberson]

imagesc() is not suitable for extracting frames. If you have binary frames just write double() of the logical array to the video.

https://www.mathworks.com/help/matlab/ref/videowriter.html

Answer 1

[Kiran Felix Robert]

Hi Feihao,

It is my understanding that you have a series of binary matrices and you want to write those to a video file.

This can be done by mapping the logical matrix to an equivalent grayscale image and writing the grayscale image, frame by frame to a video file.

For more information, refer to the videoWriter documentation. This answer contains an example to create a video from a series of images.

The following is an example to create a video from binary matrices, (I have generated 3 random binary matrices just before writing it to file, you can use indexing to access the pre-calculated matrix)

map = colormap(gray(256)); % Define the colour map for Grayscale image 
v = VideoWriter('myVideo.avi','Indexed AVI'); % Video Writer Object 
v.Colormap = map;   % Assign the colourmap 
open(v) % Open the Video Writer Object 

for u = 1:3  % Writing three images to video 
X = 255*randi([0 1],256,256); % I am creating a binary random matrix and 
                               % mapping the 0 -> 0 and 1 -> 255 to make it  
                               % as an 8-bit gray scale image 
    for z = 1:300  % Time for each frame 
        writeVideo(v,X)  % Video writer 
    end 
end 
close(v) % Close the videoWriter 

Hope this Helps

Kiran Felix Robert

[Walter Roberson]

You would have to onvert X to uint8 for that to work.

... But you can just use

X = randi([0 1],256,256)

without converting to 0 and 255 and without converting to uint8. writeVideo knows to treat single() and double() in the range of 0 to 1 as relative intensities and will construct the appropriate uint8 internally.