Click this link to download the dll for Focal3RandomImage web part
GAC it the Focal3RandomImage .dll and paste the following code in tag your web.config file
< SafeControl Assembly="Focal3RandomImage, Version=1.0.0.0, Culture=neutral, PublicKeyToken=fd89fa4a8c9d5760" Namespace="Focal3RandomImage.SharePoint.WebParts" TypeName="*" Safe="True" />
Replace the XXXXXXXXXXXXXX with publickeyToken value from GAC.
Import the Webpart From Home Site-->Site Settings-->Modify All Site Settings--> Web Parts -->New
Choose the Focal3RandomImage Web part and Populate it .
Add the Web Part in the Page From Web Part Gallery
Set The Picture Library Name with full Path(Example http://focal3.com/piclibraray/) and click Ok then Publish
The Web Part Will look like the following Image
While Refreshing or reloading the page the images will change randomly based on the picture library.
