A PCT file is a Macintosh Picture Image file format that was the default file format for Apple QuickDraw programme. It was developed by Apple but after the discontinuation of QuickDraw programme, it is no more in use. PDF, at large, has replaced the PCT and similar file formats. PCT files can also be sometimes found with .pict file extension, though both PCT and PICT have the same file format.
PCT File Format - More Information
PCT files are saved to disc as binary files in pict file format and their internal file format details are not available. Applications that can open PCT files include XnView, GIMP, Corel PaintShop Pro, and Apple Preview.
Types of PCT File Format
The image data in a Macintosh PCT file may be saved in the original PICT 1 format or as PICT 2 format.
PICT 1 - This type of PICT file format can store eight colors
PICT 2 - This type of PICT file format supports thousands of colors with 24 and 32-bit images