How to display the image that is stored in documents and static resources

   <apex: image> :
               This tag is used to display the image in VF pages.


    Syntax for the image stored in static resources.

        <apex:image id="theImage" value="{!$Resource.resource_name}" width="50" height="50"/>


   Syntax for the image stored in Documents.

       <apex:image id="theImage"
              value="https://c.<Instance>.content.force.com/servlet/servlet.ImageServer?
               id=<document_Id> &oid=<organization_id>" width="50" height="50" />

       Here,     <instance> represents a part of salesforce account url

           ex: https://ap1.salesforce.com/home

                ap1----------> instance

           

          <document_id> represents the image id where it is stored.

       <organization_id> represetns the organization id

             

                        steps to find the organization_id

                1. Go to setup

                2. Search "company information" in the quick find box.

                3. you find the salesforce.com organiztion_id or you check in the url