What is MIME type "image/x-cmu-raster"?

A MIME type is a string that tells browsers and other tools how to handle a particular kind of file.

image/x-cmu-raster is a bitmap image format for storing raster graphics. It encodes image data with a simple header that holds dimensions, color depth, and palette information, followed by the raw pixel data.
Originally developed at Carnegie Mellon University, it was intended for straightforward image processing in legacy systems and specialized software.

Main Use Case: Storing and displaying simple, uncompressed raster images.
Handles both monochrome and color images.
Favored in older Unix environments and similar contexts where simple image representation is needed.
Offers an uncomplicated structure ideal for basic image manipulation and legacy applications.

Files using this MIME type usually have the extension RAS.
Additional technical details can be found on resources like Wikipedia.

Associated file extensions

.ras

Usage Examples

HTTP Header

When serving content with this MIME type, set the Content-Type header:


    Content-Type: image/x-cmu-raster

HTML

In HTML, you can specify the MIME type in various elements:


    <a href="file.dat" type="image/x-cmu-raster">Download file</a>

Server-side (Node.js)

Setting the Content-Type header in Node.js:


    const http = require('http');
    
    http.createServer((req, res) => {
      res.setHeader('Content-Type', 'image/x-cmu-raster');
      res.end('Content here');
    }).listen(3000);

Associated file extensions

.ras

FAQ

What is a MIME type?

A MIME (Multipurpose Internet Mail Extensions) type is a standard that indicates the nature and format of a document, file, or assortment of bytes. MIME types are defined and standardized in IETF's RFC 6838.

MIME types are important because they help browsers and servers understand how to process a file. When a browser receives a file from a server, it uses the MIME type to determine how to display or handle the content, whether it's an image to display, a PDF to open in a viewer, or a video to play.

MIME types consist of a type and a subtype, separated by a slash (e.g., text/html, image/jpeg, application/pdf). Some MIME types also include optional parameters.

How do I find the MIME type for a file?

You can check the file extension or use a file identification tool such as file --mime-type on the command line. Many programming languages also provide libraries to detect MIME types.

Why are multiple MIME types listed for one extension?

Different applications and historical conventions may use alternative MIME identifiers for the same kind of file. Showing them all helps ensure compatibility across systems.