PICT

PICT is a graphics file format introduced on the original Apple Macintosh computer as its standard format. It allows the interchange of graphics (both bitmapped and vector), and some limited text support, between Mac applications, and was the native graphics format of QuickDraw.

The PICT file format consists essentially of QuickDraw opcodes. The original version, PICT 1, was designed to be as compact as possible while describing vector graphics. To this end, it featured single byte opcodes, many of which embodied operations such as "do the previous operation again". As such it was quite memory efficient, but not very expandable. With the introduction of the Macintosh II and Color QuickDraw, PICT was revised to version 2. This version featured 16-bit opcodes and numerous changes which enhanced its utility. PICT 1 opcodes were supported as a subset for backward compatibility.

Within a Mac application, any sequence of drawing operations could be simply recorded/encoded to the PICT format by opening a "Picture", then closing it after issuing the required commands. By saving the resulting byte stream as a resource, a PICT resource resulted, which could be loaded and played back at any time. The same stream could be saved to a data file on disk (with 512 bytes of unused header space added) as a PICT file.

With the change from QuickDraw to the Quartz imaging model in Mac OS X, PICT was dropped in favor of Portable Document Format (PDF) as the native metafile format, though PICT support is retained by many applications as it was widely supported in Classic Mac OS.

Recent versions of Adobe Photoshop, starting with CS5 in 2010, can only open bitmapped PICT files and can no longer save files in PICT format.

PICT versions
The PICT format has 2 different versions:
 * PICT 1 format: The original format allowed only up to 8 colors — 6 from the Apple logo, plus black and white. Designed for the original monochrome Macintosh computers, it supported black-and-white bitmaps as well as basic objects which could be output from the original release of MacDraw. Data can be compressed through the PackBits routine, a scheme introduced in MacPaint.
 * PICT 2 format: This updated format supported 4, 8 (color or grayscale), 16, and 24-bit RGB color. 32-bit color PICTs could be output with an alpha channel, but was not supported. Vector object support was also enhanced.

Compression method
With QuickTime 2.0 (a multimedia framework created by Apple Computer), bitmapped PICT files could be compressed using JPEG compression or any other QuickTime compressor.