Take the average from a region of a plot and subtract the background

I have a histogram ranging from 0 to 700 (along X axis). It is an exponential decay curve. I want to take the average from 600 to 700. This average is the background. I want to subtract this background from the plot. How can I perform this in Matlab?

Answer 1

[Image Analyst]

Try this:

binaryImage = grayImage > 600;
meanGL = mean(grayImage(binaryImage ))
newImage = double(grayImage) - meanGL; % Casting to double is needed to get negative values.
imshow(newImage, []); % The [] is needed.

[aneps]

My data is not image. The data is uploaded in this link "VMIVolt_2.asc" This is 43MB so, i couldn't upload here. https://www.transferbigfiles.com/82e1a01d-0498-4660-b6d8-b0a37fb666f5/TwMc8KZRYBlf3QFIejF_bw2

I have used the following code to plot. From this plot, I want to do the background subtraction (lets say from 620 to 720 in this plot)

A=textread('VMIVolt_2.asc');

t=0:1:1000;

h=hist(A(:,1)./1000,t);

plot(t,h)

[Image Analyst]

Then just calculate the mean from the histogram

meanBin = (sum of bins times counts) / (sum of counts)

Just the standard formula for calculating the mean.

[Image Analyst]

On your last edit.....Did you try

meanBinIndex = sum(t .* h) / sum(h);

???

[aneps]

Yes, this will do the averaging for the whole range, right? I just want to get the mean in the range,let's say 620 to 720. And then take this as backgroud and subtract this mean from the entire data. (I am sorry, I am not good in programing!)

[Image Analyst]

Then take just that range. Are you familiar with indexing?

meanBinIndex = sum(t(620:720) .* h(620:720)) / sum(h(620:720));

[aneps]

Yes, I know indexing a little bit. This meanBinIndex gives the mean in the range 620 to 720 right? If so, I guess, this value can be used as the background.

[Image Analyst]

It should give you the mean t in the histogram. Because your t starts at 0, you can find the index, if you need it, by adding 1. If you need just the t value, you don't need to add 1.