How to count the total number of blink?

Hi, I'm doing research on how count total number of blinks, is there any good resource for this task?

Thank You

Answer 1

[Bora Eryilmaz]

You can use a peak detection algorithm such as the islocalmax() command: https://www.mathworks.com/help/matlab/ref/islocalmax.html

x = randn(100,1);
plot(x)
hold on

level = 1.0;
yline(level, 'r')

% Only find peaks above the level.
I = (x < level);
x(I) = 0;

% Indices of all peaks above level.
J = islocalmax(x);
count = sum(J) % Number of peaks

count = 17

plot(find(J), x(J), 'ro')

% Indices of the peaks above level that are at least 5 x-units apart.
J = islocalmax(x, 'MinSeparation', 5);
count = sum(J) % Number of peaks

count = 11

plot(find(J), x(J), 'bx')
hold off

[Image Analyst]

If you want/need to consider long blinks (covering several adjacent indexes) as a single blink, then see my answer below, which uses regionprops

[Bora Eryilmaz]

MinSeparation property of the islocalmax command handles this concern. You can specify the minimum required distance between nearby peaks.

[nazmican]

How can I do it?

[Bora Eryilmaz]

See updated code above.

[nazmican]

Thank you

Answer 2

[Image Analyst]

Not sure what "detect" means to you. But if the red line is your threshold and signals above the threshold are a blink, then you can count them with bwlabel". If you want to know what indexes contains a blink signal, you can use regionprops.

signal = rand(1, 200); % Sample signal
plot(signal, 'b-');
grid on;
xlabel('Index');
ylabel('Signal');
threshold = 0.9;
yline(threshold, 'Color', 'r', 'LineWidth',2)

binarySignal = signal > threshold;
[~, numBlinks] = bwlabel(binarySignal);
% If you want indexes of the blink runs, then you can use regionprops
props = regionprops(binarySignal, 'PixelIdxList')

props = 12×1 struct array with fields:
    PixelIdxList

% Print them out
for k = 1 : numel(props)
    theseIndexes = props(k).PixelIdxList;
    fprintf('For region #%d, it has indexes : ', k)
    fprintf('%d ', theseIndexes)
    fprintf('\n')
end

For region #1, it has indexes : 

13 

For region #2, it has indexes : 

61 

For region #3, it has indexes : 

71 

For region #4, it has indexes : 

75 

For region #5, it has indexes : 

81 

For region #6, it has indexes : 

84 85 

For region #7, it has indexes : 

100 

For region #8, it has indexes : 

140 141 

For region #9, it has indexes : 

148 149 

For region #10, it has indexes : 

174 

For region #11, it has indexes : 

177 

For region #12, it has indexes : 

194 

[nazmican]

I want to total number of blinks in EEG data.

function BlinkCount = CountBlinks(EEGdata, threshold, windowLen)
%First finds the blink segments which are above threshold value
Blink_indices=find(EEGdata>threshold);
Blink_indices=ceil(Blink_indices/windowLen);
% Then sets the artifact states as blink=1 or normal=0
artifactStates=zeros(1,length(EEGdata)/windowLen);
artifactStates(Blink_indices)=1;
BlinkCount=sum(artifactStates);
end

[nazmican]

I tried to do it with this code but I got an error.

[Bora Eryilmaz]

The code in this answer would require the Image Processing Toolbox.

[Image Analyst]

Uh, that's not my code. You should contact the author for a fix.