MATLAB: Peak width calculation methods

Question

Hi

I'm calculating peak width using half-prominence method . For the peak in the rectangle is there is a method to make the horizontal line the finds the widths to shift up or make vertical line like this image

? . I tried both methods for peak width detection (half-width, half-prominence ) but it gave me the same results .

Half-prominence

 close all
order =9 ;
framelen =15;
lx = 20;
% generate sinal
x = 1:1:1432;
y = (AV)';
y = sgolayfilt(y,order,framelen);
% get derivatives
dy = diff(y);
dx = diff(x);
dy_dx = [0 dy./dx];
 findpeaks(y,x,'Annotate','extents','MinPeakProminence',0.006);
% get peaks with width computed by 'findpeaks'
 [pks,locs,peakWidth1,p] = findpeaks(y,x,'MinPeakProminence',0.006);

half-height :

order =7 ;
framelen =11;
x=-AV;
lx = 20;
 sgf = sgolayfilt(x,order,framelen);
hold on;
sgf= 0.02-sgf;
findpeaks(sgf,'MinPeakProminence',0.004,'WidthReference','halfheight','Annotate','extents');
[pks,locs,widths,proms]=findpeaks(sgf,'MinPeakProminence',0.004,'WidthReference','halfheight');
 pks = -pks;
plot(locs,pks,'g*');
text(locs+.02,pks,num2str((1:numel(pks))'));

Answer 1

It seems you are interested in the relative height of the spike with its immediate vicinity (not with respect to higher peaks). To do that, try subtracting off the results of a lowpass or median filter first.

findpeaks(sgf - medfilt1(sgf,21), ...)