What is the PCT file format?
.pct is the Windows-compatible file extension for Apple's PICT format (QuickDraw Picture), the native graphics metafile of classic Mac OS. PICT was introduced with the original 128K Macintosh in January 1984 and remained the standard Mac graphics exchange format for nearly two decades.
A .pct file can hold vector drawing commands, bitmapped imagery, text, or any combination, encoded as a sequence of QuickDraw opcodes. Files typically begin with a 512-byte null header - an artifact of the classic Mac resource fork model - followed by the opcode stream. Two main versions exist: PICT v1 (monochrome, 1984) and PICT v2 (Color QuickDraw, 1987); a QuickTime-extended variant supports embedded JPEG or PNG imagery. The .pict extension is used for the same format on macOS.
On Windows, .pct files required QuickTime for Windows (discontinued 2016) or third-party tools such as IrfanView, XnView, or GIMP. Apple Preview continues to open .pct files on macOS, though macOS 10.15 Catalina (2019) removed the QuickTime 7 components many other apps depended on. The format has been superseded by PDF and PNG as macOS's standard graphics formats.
Security & safety
RISK: LOWStatic image format; no macros or executable code. No known exploits in current viewers. Safe to open.
Format details
in a nutshellPrograms that open PCT files
Windows8 apps
Adobe Photoshop
Paid File → Open → select PCT file. Photoshop reads PICT bitmaps; complex vector PICT may be partially rasterized. 
macOS3 apps
Technical details
deep spec| Format type | Metafile (QuickDraw opcodes - vector and/or raster combined) |
| Encoding | Binary |
| Byte order | Big-endian (Motorola 68k / PowerPC Mac byte order) |
| File header | 512-byte null header (resource fork stub) followed by QuickDraw opcode stream |
| Version identification | PICT v1: opcode 11 01 at offset 522; PICT v2: sequence 00 11 02 FF 0C 00 at offset 522 |
| Versions | PICT v1 (1984, monochrome); PICT v2 (1987, Color QuickDraw); QuickTime-extended (JPEG/PNG embedding) |
| Color depth | 1 bpp (PICT v1, monochrome); 1-32 bpp (PICT v2, color) |
| Compression | None (basic); optional PackBits RLE for bitmap data; QuickTime JPEG or PNG in extended variant |
| Dimensions limit | 32,767 × 32,767 pixels (16-bit signed bounding rectangle) |
| MIME type | image/x-pict |
| Associated OS | macOS / Classic Mac OS (primary); Windows (legacy, via QuickTime or third-party tools) |
| Mac storage model | Stored in resource fork on Classic Mac; data fork on modern systems and Windows |
| Current status | Legacy; superseded by PDF and PNG on macOS; Apple Preview still reads the format |
| Related extension | .pict (macOS-native naming for the same format) |
| Released | 1984 (original Macintosh with QuickDraw) |
| Latest version | PICT2 (Color QuickDraw, 1987); QuickTime-extended PICT |
| Specification | www.fileformat.info |
PCT conversions
Community Q&A
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