Calculating Histogram of an Image in MATLAB ( without using inbuilt functions)

Write a MATLAB script to calculate and plot a histogram of a given image .

 

**Check the plotted histogram  vs the Histogram created using imhist().
**If both the histograms look similar , then the code is correct. 

**The first step for calculating a histogram will be finding out the gray image of the input image .

Try to do this also using custom code and not use rgb2gray()

OUTPUT

Feel free to download and use this code.

** For those who do not have access to MATLAB ( extremely expensive  !!! ) ,  i will be releasing similar code in OpenCV soon . **

If you can suggest any optimisations , or useful changes to the given code , then do leave your valuable suggestions as comments .