How to get smoothed plot of a grayscale image?

 I am trying to get the smoothed plot of this converted 
 grayscale image plot. Can anyone provide code how we can get a smoothed
 plot.In picture you can see formula for a smooth plot.For example i have plotted 
 values of a grayscale image as follows

 grayImage=imread('capture')
 counts = histcounts(grayImage, 0:256)
 plot(counts)

[jonas]

Perhaps imgaussfilt is what you are looking for?