how i can thresholding a signal

i want to threshold a signal please help me

[Walter Roberson]

How do you want to compute the threshold level?

[RESHMA]

i have a received signal in my matlab project , i want to just threshold that signal to a value of 5

Answer 1

[Image Analyst]

Try this:

thresholdedSignal = yourSignal < someThresholdLevel; % Or can use > if you want.

[RESHMA]

thank u but i have already tried this and got the answer

[Giorgio]

He is asking how to threshold a signal and you answered x < T. Which T?

What he is asking is "how to find T." If you know please let us know. Of course we want that but the problem is how to find the someThresholdLevel....

I can recommend to use something like this:

nbins = 128;
counts = hist(signal, nbins);
T = otsuthresh(counts);

press help otsuthresh

It computes a global threshold from histogram counts COUNTS that minimizes the intraclass variance for a bimodal histogram. T is a normalized intensity value that lies in the range [0,1]

You can use thr as theshold:

thr = round(T * nbins)

you can use the values associated to bins over/below the thr ...

[Image Analyst]

The T depends on the image. Sometimes the Otsu method works, and sometimes it doesn't. You can try imbinarize(). It works well for nice, bimodal histograms that you get with high contrast images. It doesn't work so well with mono-modal skewed histograms.

Usually I find I have skewed histogram and what I find works best is a triangle threshold, like in my attached function.