A bitmap that is stored in compressed form using the RLE algorithm. SGI chromaticity ranges from 8 to 32 bits/pixel. The format is designed for use on Silicon Graphics workstations. It is also known as Irix RGB or IRIS.
This format was developed by Apple for storing vector and bitmap images with metadata. It was the main format for the QuickDraw graphics software. PCT supports 32-bit and 24-bit images. At the moment, the format is obsolete and has been superseded by more functional solutions.