P4Thumb, the Helix Thumbnail Generator, creates thumbnails of graphic files managed by Helix Core and stores them in the Helix Core server, also called the Helix server. A thumbnail is a 160x160 pixel PNG representation of the image. P4V, the Helix Visual Client, displays the thumbnails in the right pane when you choose View > Show Files As > (Large/Medium/Small) Thumbnail.
P4V does not communicate directly with P4Thumb; instead, it obtains thumbnails from the server.
By default, P4V displays thumbnails for image files located in the workspace. If you install and configure P4Thumb, P4V can also display thumbnails for any revisions of graphic files stored in the server.
Before running P4Thumb, you need to create a dedicated client (workspace). This client only maps directories containing image files that require thumbnails. A thumbnail is stored as a Revision attribute named thumb. P4V recognizes this attribute. You can read this attribute with the fstat function (for example: p4 fstat -Oae -A thumb //depot/images/luftballon.jpg#1).
When you start P4Thumb against a server for the first time, it creates thumbnails for all graphic file versions in its client view and then adds thumbnails for any new image versions as they get added to the depot.
Make sure to start only one P4Thumb server. Starting two servers that map the same directories in their respective clients would result in two competing P4Thumb servers managing the same set of attributes.