How to know the color hexadecimal value of the picture or screen display

If you see the specific color of one picture or displayed in the computer screen,  and  you want to copy that color to your project, so your project have the same color. How to do that? 
You have to know the hexa value  of that color. 
To know the hexadecimal value of the picture color we need the tool called WhatColor, you can download from this link

When you edit the picture, when you edit the template of the blog or web page, edit the color of the font,  you need this tool.
Run the program, you can see the hexadecimal value follow the mouse pointer (cursor). Press F12 to copy.