SGI

Silicon Graphics Image

image/sgi Released 1990 · by Paul Haeberli (Silicon Graphics)

The image/sgi MIME type represents the Silicon Graphics Image format, the native raster graphics file format developed by Paul Haeberli for Silicon Graphics (SGI) workstations. Extensively used in 1990s 3D animation, CGI rendering, and high-end visual effects workflows, it supports up to 16-bit color per channel and Run-Length Encoding (RLE).

Legacy & 3D Graphics Transparency Production Ready

Technical Specifications

MIME Type

image/sgi

Extensions

.sgi.rgb.rgba.bw.int.inta

Container

SGI Image Format

Compression

Uncompressed & Lossless (Run-Length Encoding)

Algorithms

RLENone

Color Depth

8-bit, 16-bit (Per Channel)

Metadata

None

Capabilities

Transparency

Animation

Progressive Loading

Alpha Channel

HDR Support

Official Specification

Aliases: image/x-sgiimage/rgbimage/x-rgb

Magic Bytes & HTTP Headers

File Signature (Magic Bytes)

01 DA

ASCII: \x01\xda

HTTP Headers

Content-Type: image/sgi

HTML Accept Attribute

accept="image/sgi, image/x-sgi, image/rgb, .sgi, .rgb, .rgba"

Browser Support Matrix

Browser	Status	Min Version
Chrome	Not Supported	—
Firefox	Not Supported	—
Safari	Not Supported	—
Edge	Not Supported	—
Internet Explorer	Not Supported	Legacy

Advantages & Limitations

Advantages

Pioneered multi-channel and 16-bit per channel imaging capabilities required for high-end 1990s visual effects
Extremely robust and simple header structure
Reliable Run-Length Encoding provided solid lossless compression for flat-shaded 3D renders

Limitations

Completely obsolete for modern web and application development
Zero native web browser compatibility
Largely replaced by TIFF and OpenEXR in modern professional VFX and 3D pipelines

Developer Code Snippets

import magic
print(magic.from_file('render.sgi', mime=True)) # May output 'image/x-sgi'

const FileType = require('file-type');
const type = await FileType.fromFile('render.sgi');
console.log(type?.mime); // Modern parsers may lack support for SGI and return undefined

import "net/http"
// Custom detection required: bytes.HasPrefix(buf, []byte{0x01, 0xDA})

$mime = mime_content_type('render.sgi');
echo $mime; // Standard setups will often output 'application/octet-stream'

File Detection Steps

How to programmatically detect a image/sgi file by reading its raw bytes:

1 Check the first two bytes for the SGI magic number: 01 DA (hex)
2 Read the byte at offset 2 to determine the storage method (0 for uncompressed, 1 for RLE)

Software Support

ImageMagick

GIMP

F

FFmpeg

X

XnView

Conversion Tools

Share & Embed

Markdown Badge

[![SGI Format](https://freewebptojpg.com/mime/image/sgi/badge.svg)](https://freewebptojpg.com/mime/image/sgi)

Interactive iframe Widget

<iframe src="https://freewebptojpg.com/mime/image/sgi/embed" width="100%" height="280" style="border:1px solid #cbd5e1;border-radius:8px;" title="SGI Specs"></iframe>

JSON API

All data on this page is available as a free, open JSON API. Use it in your project, documentation, or tooling.

GET https://freewebptojpg.com/mime/image/sgi.json Open JSON

Free to use

No auth required

CORS enabled

Use from any domain

Cached 24h

Cache-Control headers set

Frequently Asked Questions

What is an SGI file?

An SGI file is a raster graphics file originally used on Silicon Graphics (SGI) workstations running the IRIX operating system. It was the standard image format for high-end 3D graphics software like early versions of Alias and Maya.

What is the difference between .sgi, .rgb, and .bw files?

They are technically the exact same file format. The extensions were used historically as hints to the file's color channels: .bw for black and white (1 channel), .rgb for color (3 channels), and .rgba for color with alpha (4 channels).

What is the magic byte for an SGI file?

All valid SGI image files begin with a 2-byte magic number: 01 DA (in hex).