Silicon Graphics Image (.sgi)

The Silicon Graphics Image (SGI) file format, also known as the RGB file format, is a raster graphics file format developed by Silicon Graphics Inc. (SGI) for their workstations. Created by Paul Haeberli in 1995, this format is designed to store color images with high fidelity. SGI files can store images with 8 to 32 bits per pixel, allowing for a wide range of color depths and image qualities. The format supports three primary color channels (red, green, and blue) and can also include an alpha channel for transparency, resulting in files with extensions such as SGI, RGB, and RGBA. The SGI format is notable for its ability to use run-length encoding (RLE) compression, which helps reduce file sizes without significantly compromising image quality. This makes it particularly useful for applications requiring high-quality images with efficient storage, such as graphic design, animation, and visual effects.

SGI files are primarily associated with Silicon Graphics workstations, which were widely used in the 1990s for tasks requiring advanced graphics capabilities. These workstations and their native file format played a significant role in industries such as film production, scientific visualization, and computer-aided design (CAD). The SGI format's structure includes a header that specifies details like image dimensions, number of channels, and compression type. The format uses big-endian byte order and scans image data from left to right, bottom to top. Despite the decline of Silicon Graphics Inc. and their workstations, the SGI file format remains supported by various modern image viewers and editors. This enduring support ensures that SGI files can still be accessed and utilized in contemporary digital workflows.