obtaining magnitude of histogram plot

I have plot the histogram of an image using imhist() function. I want to obtain the magnitude of the histogram plot. imhist() returns 2 arguments : counts and x.

img=imread('C:\Users\Divya\Desktop\1_2_1.bmp');
img1=rgb2gray(img);
[counts x]=imhist(img1,20000);

counts and x both are 20000*1 array. It does not provide information about the whole image

Any pointers on how i can obtain this data?