PICT format is used in Mac OS graphics and page-layout applications as an intermediary file format for transferring images between applications. PICT format supports RGB images with a single alpha channel and Indexed Color, Grayscale, and Bitmap mode images without alpha channels. PICT format is especially effective for compressing images with large areas of solid color. This compression can be substantial for alpha channels with their large areas of white and black.

When saving an RGB image in PICT format, you can choose either a 16‑bit or 32‑bit pixel resolution. For bitmap and grayscale images, you can choose from 2, 4, or 8 bits per pixel. In Mac OS with QuickTime™ installed, four JPEG compression options are available.