92 lines
2.3 KiB
Matlab
92 lines
2.3 KiB
Matlab
%hr = heartRateEstimation(imgDirectory, fps, windowDuration, windowShift)
|
|
%%%%%%%%%%%%%%%%%
|
|
% hr = heartRateEstimation(imgDirectory, fps, windowDuration, windowShift)
|
|
%
|
|
% Task: Finding the heartrate of person from selcted images
|
|
%
|
|
% Inputs:
|
|
% -imgDirectory
|
|
% -fps
|
|
%
|
|
% Output:
|
|
% -heartrate:
|
|
%
|
|
% Author: Thomas Périn
|
|
% Date: 17/02/2023
|
|
%
|
|
% Note: images were extracted with ffmpeg -i "video.mkv" ../img/gg_%04d.png
|
|
%%%%%%%%%%%%%%%%%
|
|
|
|
clc
|
|
clear all
|
|
|
|
% temp var
|
|
fps = 15;
|
|
windowDuration = 30;
|
|
roi = [280 580 600 850];
|
|
|
|
% global
|
|
redChannel = [];
|
|
greenChannel = [];
|
|
blueChannel = [];
|
|
|
|
%list the images with i the same directory
|
|
listImg = dir(['*.png']);
|
|
|
|
% iteration for every images available
|
|
for l_img=1:windowDuration*fps
|
|
% load the current image
|
|
image_original = imread([listImg(l_img).name]);
|
|
|
|
% crop the current image around the face
|
|
image_face = image_original(roi(1):roi(2), roi(3):roi(4), :);
|
|
|
|
% spatial average for r, g, b channels
|
|
r_mean = mean(mean(image_face(:,:,1)));
|
|
g_mean = mean(mean(image_face(:,:,2)));
|
|
b_mean = mean(mean(image_face(:,:,3)));
|
|
|
|
% store the current "average" pixel in global arrays
|
|
redChannel = [redChannel r_mean];
|
|
greenChannel = [greenChannel g_mean];
|
|
blueChannel = [blueChannel b_mean];
|
|
end
|
|
|
|
% estimate temporal average and standard deviation
|
|
redChannel_avg = mean(redChannel);
|
|
redChannel_std = std(redChannel);
|
|
greenChannel_avg = mean(greenChannel);
|
|
greenChannel_std = std(greenChannel);
|
|
blueChannel_avg = mean(blueChannel);
|
|
blueChannel_std = std(blueChannel);
|
|
|
|
% normalize your data
|
|
% first define length of our data
|
|
L = columns(greenChannel);
|
|
for i=1:L
|
|
greenChannel_normalized(i) = (greenChannel(i) - greenChannel_avg)/greenChannel_std;
|
|
end
|
|
|
|
% select only greenChannel for simplicity (no ICA)
|
|
greenChannel_fft = fft(greenChannel_normalized);
|
|
|
|
% power spectrum using link(https://www.mathworks.com/help/matlab/ref/fft.html)
|
|
P2 = abs(greenChannel_fft/L);
|
|
P1 = P2(1:L/2+1);
|
|
P1(2:end-1) = 2*P1(2:end-1);
|
|
f = 15*(0:(L/2))/L;
|
|
plot(f,P1)
|
|
|
|
% find the peak in the range ([0.75 4] Hz)
|
|
% define range and round to get intergers
|
|
low_index = round(0.75*L/15);
|
|
high_index = round(2*L/15);
|
|
% find max value and index inn new range
|
|
[a, ia] = max(P1(low_index:high_index));
|
|
% adapt the index for full range
|
|
heart_frequency = f(ia+low_index)
|
|
|
|
% determine heart rate
|
|
% convert the index from Hz to bpm
|
|
heart_rate = heart_frequency*60
|