Hi,
You can use the VideoReader function to read a video file to MATLAB, and then use its various properties and object functions to access each frame individually as an image.
Then, for each frame, perform some preprocessing to bring all pixels down to a standard indication of redness, by subtracting the grayscale values from the red channel. Find the pixels that have Red intensity higher than a certain threshold value, and count these instances. Finally, find the percentage of the total number of pixels.
The below code should work:
vid = VideoReader('<video file location>');
redPixelCount = 0;
thresholdValue = 100;
frameCount = vid.NumFrames;
red = zeros(1,frameCount);
i=1;
while hasFrame(vid)
frame = readFrame(vid);
redChannel = imsubtract(frame(:,:,1), rgb2gray(frame));
redMask = redChannel > thresholdValue;
redPixelCount = sum(redMask(:));
redAreaPercent = (redPixelCount / numel(frame(:,:,1))) * 100;
red(i) = redAreaPercent;
i = i+1;
end
The thresholdValue is what may be used to define the "red", in your instance. From some trial and error, I found out that something between 90 and 160 should be fine.
Hope this helps!
