SGI File

What are SGI files and how to open them

Are you having problems opening a SGI file or are you simply curious about its contents? We're here to explain the properties of these files and provide you with software that can open or handle your SGI files.

What is a SGI file?

A .SGI file is a Silicon Graphics Bitmap file.

Silicon Graphics Bitmap (.sgi / .rgb / .rgba) is a raster image format designed by Silicon Graphics for storing black-and-white, grayscale, RGB color, or RGB with alpha channel images. It was originally used to save screen renderings, color maps, and image files on SGI workstations running IRIX, and remains supported by graphics and image-processing applications. Files may be created in either uncompressed form or using lossless run-length encoding (RLE) to reduce size without losing image fidelity.

An SGI image file begins with a 512-byte header that records image width, height, number of color or bit-planes (channels), and per-channel byte depth (usually one or two bytes per pixel component), plus a name field and type flag describing whether data are raw or RLE compressed. After the header, uncompressed image data follows plane-by-plane scanlines; if RLE is used, offset tables appear immediately after the header to locate each scanline's compressed data. In all cases, scanlines are ordered from bottom to top (first line is bottom of image).

Technical details: the file signature or magic number at offset 0 is decimal 474 stored in two bytes (big-endian), storage flag is a byte indicating 0 for uncompressed or 1 for RLE, another byte gives bytes-per-channel (1 or 2), two-byte fields give dimension count, width (XSize), height (YSize), and number of channels (ZSize).

How to open SGI files

We have identified two SGI openers that are compatible with this specific type of SGI file.

Programs that open Silicon Graphics Bitmap files

Last updated: August 5, 2026

Various apps that use files with this extension

These apps are known to open certain types of SGI files. Remember, different programs may use SGI files for different purposes, so you may need to try out a few of them to be able to open your specific file.

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