Painter PIX
From Just Solve the File Format Problem
Early Painter software would create a "PREVIEW.PIX" file which contained a thumbnail of every file in the folder.[1] This thumbnail would display when opening the file in Painter.
File Information
PREVIEW.PIX files begin with the hex values 00000100, then end with a list of filenames for the thumbnails it contains. Thumbnails appear to in the PICT format.
