Plot multiple histograms in one figure and re-plot the overlay histogram

I used the code provided by Image Analyst to plot multiple RGB histograms in one figure, the result is shown in the following figure.

I want plot a new histogram based on the overlaid histograms. I don't know how to put it in words about what I want to do but it is something like this...

 I'm not sure how to do it. Can anyone help me please?

[Crystiano Martins]

Hi , can u send the code u made ? i think u want to do somethink like this :

figure(1);
im = imread('name1.jpg');
im2 = imread('name2.jpg');
im3 = imread('name3.jpg');
imhist(im);
hold on 
imhist(im2);
hold on 
imhist(im3);

[Lim]

The code is from Image Analyst, named 'RGB_Histogram_Demo', I grabbed it from one of his Answers. The histograms are actually histogram of red, green and blue color channels of the same image. I read one image and extract the RGB. I want to know how do I plot/highlight only the un-overlapped part like the dark line in the second figure.

[Lim]

Image = imread('001.bmp');
Red = Image(:,:,1);
Green = Image(:,:,2);
Blue = Image(:,:,3);
[pixelCountRed grayLevels] = imhist(Red, 256);
[pixelCountGreen grayLevels] = imhist(Green, 256);
[pixelCountBlue grayLevels] = imhist(Blue, 256);
plot(pixelCountRed, 'r');
hold on;
plot(pixelCountGreen, 'g');
plot(pixelCountBlue, 'b');

Until this point, it will develop a plot with three histogram in one figure, as shown in figure above. May I know how do I plot the maximum lines of the histogram so it shows one graph with six peaks (as in the example figure)?