What is MIME type "image/x-raw-sigma"?

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

The MIME type image/x-raw-sigma is used for raw image files produced by Sigma digital cameras. It represents unprocessed sensor data that retains full detail for later editing.

Files using this format commonly use the extension X3F, which captures the camera's detailed image information.

High quality data: Keeps full sensor detail for greater flexibility in editing.
Metadata rich: Stores shooting information and camera settings.
Post-processing capability: Enables adjustments like exposure and white balance after capture.

This format is preferred by photographers who demand precise image control and may require special software or plugins to view and edit.

For more technical information on MIME types, visit MIME Types on Wikipedia.

Associated file extensions

.x3f

Usage Examples

HTTP Header

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


    Content-Type: image/x-raw-sigma

HTML

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


    <a href="file.dat" type="image/x-raw-sigma">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-raw-sigma');    
      res.end('Content here');    
    }).listen(3000);

Associated file extensions

.x3f

FAQs

Do web browsers support the image/x-raw-sigma MIME type?

No, modern web browsers like Chrome, Firefox, and Safari do not natively render X3F files. To display these images on a website, you must convert them to a standard web format like image/jpeg or image/png using software like Sigma Photo Pro or Adobe Lightroom.

How do I open a file with the image/x-raw-sigma content type?

You need specialized image processing software to view and edit these files. The primary application is Sigma Photo Pro, which is designed specifically for the Foveon sensor data found in Sigma cameras, though third-party tools like Adobe Photoshop (via Camera Raw) also support the format.

How do I configure Apache to serve .x3f files correctly?

You can ensure the correct MIME type is sent by adding a directive to your .htaccess file or main configuration. Add the line AddType image/x-raw-sigma .x3f to associate the extension with the MIME type.

Why does my IIS server return a 404 error when accessing .x3f files?

IIS does not serve file types it doesn't recognize by default for security reasons. To fix this, you must add a MIME Map in the IIS Manager specifically for the extension .x3f pointing to image/x-raw-sigma.

What is the correct Nginx configuration for Sigma RAW files?

To serve these files with the correct header in Nginx, locate your mime.types file or the types block in nginx.conf. Add the entry image/x-raw-sigma x3f; to ensure the server identifies the file correctly.

Why are image/x-raw-sigma files significantly larger than JPEGs?

These files contain uncompressed, unprocessed sensor data from the camera, retaining all color and lighting information. Unlike a compressed image/jpeg, which discards data to save space, image/x-raw-sigma keeps the full dynamic range for high-quality post-processing.

General 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.