You may have noticed that Facebook ads a the location revealing your wheresbouts at the times you publish post. If you don't want other to know that, this is what you need to do.
A simple Photoshop tutorial, where you may learn how to expose an object by leaving it in color while turning the rest of the photo black and white or sepia.
To ensure the authenticity of a document you have to sign the document with the certificate. I will show you how you can easily sign PDF document with the help of simple tool DigiSigner.