Convert psb to pfm

Download and install the latest version of Filestar.
Right click on one or more Psb file(s) on your desktop and select Convert with Filestar.
Type convert to pfm in the search box.
Press Convert.

What is .psb?

Name: Photoshop Large Document Format
Extension: .psb
Format: Binary
Category: Raster Image
Developer: Adobe Systems
Description: Format used for saving large Photoshop documents over 30,000 by 30,000 pixels in size; supports images up to 300,000 by 300,000 pixels; to enable .psb support, check the "Enable Large Document Format" within the File Handling pane of the Photoshop Preferences window
MIME Type: image/vnd.adobe.photoshop
Sample: sample.psb
Wikipedia: .psb on Wikipedia