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4-D uint8 , what does it mean?

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semicolon
semicolon on 7 Dec 2020
Commented: Stephan on 7 Dec 2020
Hello,
I've uploaded a video to matlab with the following code and I got this on workspace:
I want to know more about the meaning of "4-D uint8", what does it mean? what are the 4 dimentions , what is uint8 ?
what is the dimentions of the variable "frames"? How can I extract one column from the 4-D table?
Thank you
video = VideoReader("measurment.mp4");
for(i = 1: video.NumberOfFrames)
frames(:,:,:,i) = read(video, i);
end

Accepted Answer

Stephan
Stephan on 7 Dec 2020
Edited: Stephan on 7 Dec 2020
There is a 2D for height and width of the video, which shows the resolution, the 3rd D is for example is of size 3 for RGB or of size 1 for grayscale.
This 3 dimensions would describe one image. Since you have a video, there are all those single frames in the 4th dimension one after eachother.
What you want i guess is readFrame since you use a for loop. What you did is reading the whole video into one 4D array. This would not need a loop.
  5 Comments
Stephan
Stephan on 7 Dec 2020
You can access the red color channel with using index = 1 on the third dimension:
AllRedFromFrame42 = frames(:,:,1,42)
TheFirst_10_x_10_RedFromFrame13(1:10,10:,1,13)

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