How to convert google(Public) image to byte array asp.net c#

Question

I have public Image like 

 

https://csharpcorner-mindcrackerinc.netdna-ssl.com/App_Themes/CSharp/Images/SiteLogo.png 

 

 

I want to convert Public Image to Byte formates using C# ? 

 

Already I try below code 

 

byte[] imgdata = System.IO.File.ReadAllBytes(imagePath);