Why when I use find peaks is it not finding the actual first peak?

Using the findpeaks function to find the peaks of my data. It finds most peaks correctly as I used the following code:

findpeaks(ResAcceltrim,'MinPeakDistance',250,'MinPeakHeight',pe);

The distance set stops noise from interfering with the peaks, and the height is determined by what data set i'm using. In this case i believe the peak height is 4. However the first peak is not determined correctly, it is too low, see the two images below.

<<The second image is just cropped to only show the first area of the graph. As you can see the first peak is identified incorrectly.

>>

Answer 1

[Jan]

Do I see correctly, that the first peak is in the first, or the first few frames of the signal? Then you cannot expect it to be recognized as "peak" - it is none, if the signal is much higher before.

[Oliver Kohout]

I looked closer, it is not in the first frame, it still technically is a peak, since is rises before then falls. But it must be below the threshold and not being recognised.