98 lines
1.9 KiB
Matlab
98 lines
1.9 KiB
Matlab
%set variable
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fps = 15;
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windowDuration = 30;
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windowShift = 1;
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roi = [310 126 114 54];
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imgDirectory = 'images';
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%global
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redChannel = [];
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greenChannel = [];
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blueChannel = [];
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%list the images
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listImg = dir([imgDirectory '/*.png']);
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for l_img=1:windowDuration*fps
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% load the current image
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image_orginal = imread([imgDirectory '/' listImg(l_img).name]);
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image_face = imcrop(image_orginal,roi);
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%spatial average for r, g, b channels
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[r g b]=imsplit(image_face);
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r_mean = mean2(r);
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g_mean = mean2(g);
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b_mean = mean2(b);
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% store the current "average" pixel in global arrays
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redChannel = [redChannel r_mean];
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greenChannel = [greenChannel g_mean];
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blueChannel = [blueChannel b_mean];
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end
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% estimate temporal average and standard deviation
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greenChannel_avg = mean(greenChannel);
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greenChannel_std = std(greenChannel);
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%normalization
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for i = 1:450
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greenChannel_normal(i) = (greenChannel(i)-greenChannel_avg);
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end
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%Fast Fourier transform (fft) of Green Channel
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greenChannel_fft = fft(greenChannel_normal);
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%power spectrum P1
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L = length(greenChannel_normal);
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P2 = abs(greenChannel_fft/L);
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P1 = P2(1:L/2+1);
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P1(2:end-1)=2*P1(2:end-1);
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f = 15*(0:(L/2))/L;
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P1 = fftshift(P1);
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plot(f,P1);
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title("Power Spectrum")
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xlabel("frequency (Hz)")
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ylabel("Power Spectrum")
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%peak - compute the freq vector
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[m n]=size(P1);
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x = 1:n;
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y= 1:m;
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[X Y]=meshgrid(x, y);
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X = X - floor(n/2)-1;
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Y = Y - floor(m/2)-1;
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f = sqrt(X.^2 + Y.^2);
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%peak - find the peak in range
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indices = (f>=0.75)&(f<=4);
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[peaks locations] = findpeaks(P1(indices), 'SortStr','descend');
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location = locations(1);
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peak_frequency = f(indices);
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peak_frequency = peak_frequency(location);
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heartrate = peak_frequency.*60;
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disp(['Heart rate: ', num2str(heartrate), ' bpm']);
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%plotting RGB
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figure(2)
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subplot(2,2,1);
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plot(redChannel,'r');
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title('Red Channel');
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subplot(2,2,2);
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plot(greenChannel,'g');
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title('Green Channel');
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subplot(2,2,3);
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plot(blueChannel,'b');
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title('Blue Channel');
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