Problem: Photoshop files uploaded to the corporate branding portal was giving "JPEG" image icon and often caused confusion to end users!
Root cause: This is because of the DOCICON.XML file mapping in SharePoint. Out of the box, SharePoint 2010 has a icon for Photoshop files similar to JPEG Files.
Fix: We've to change icon type in SharePoint 2010. Upload new icon for Adobe Photoshop files in 14 hive, update the DOCICON.XML file and Do a IISReset!
Steps in detail: How to Add Custom File Type Icons in SharePoint?
Root cause: This is because of the DOCICON.XML file mapping in SharePoint. Out of the box, SharePoint 2010 has a icon for Photoshop files similar to JPEG Files.
Fix: We've to change icon type in SharePoint 2010. Upload new icon for Adobe Photoshop files in 14 hive, update the DOCICON.XML file and Do a IISReset!
Steps in detail: How to Add Custom File Type Icons in SharePoint?
- Grab the Photoshop document icon (of name: psd.png) of 16x16 from the Internet. Copy to: 14 hive's Images folder: C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\14\TEMPLATE\IMAGES
- Take a backup and Update the DOCICON.XML, PSD Mapping key: with <Mapping Key="psd" Value="psd.png"/> under " <ByExtension>" Node
- Run IISReset from Command line console.
You have to do these steps in all your WFEs in multi-server farm!
Before Adding PSD Icon:
After adding PSD Icons:

Same issue occurred in an another case with Auto-CAD Files. Performed the above steps with Auto-cad Icon and fixed the issue by adding icon to SharePoint with new mapping key: <Mapping Key="dwg" Value="autocad.png"/>
Don't forget to do IISReset! Here is the before
and after screen shots: SharePoint custom icon for Autocad files

Here is my old post on changing PDF Icon in SharePoint 2007: Change PDF Icon in SharePoint