What is MIME type "image/x-pentax-pef"?

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

image/x-pentax-pef is a MIME type for raw image files from Pentax digital cameras. It signals software to treat the file as an unprocessed sensor capture.

This format preserves complete image data, allowing detailed post-processing. It stores wide dynamic range, color information, and metadata.

File types in the broader Camera Raw Formats group include CR2, NEF, ARW, among others. For Pentax models, the specific raw files are PEF and PTX.

This MIME type enables imaging software to automatically recognize and properly decode the raw data.
It is key for professional editing, where preserving each detail matters.
It allows conversion into standard formats like JPEG or TIFF without immediate loss of image quality.
It is widely supported by advanced photo editors and digital asset management tools.

Applications that work with these files can extract and adjust exposure, white balance, and contrast before final output.

For more on camera raw file specifications, check the Wikipedia entry on Camera File Formats.

Associated file extensions

.cr2, .nef, .arw, .cap, .dcr, .ptx, .srf, .raf, .kdc, .orf, .mrw, .pef, .crw, .iiq, .x3f, .capture

Usage Examples

HTTP Header

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


    Content-Type: image/x-pentax-pef

HTML

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


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

Associated file extensions

.cr2, .nef, .arw, .cap, .dcr, .ptx, .srf, .raf, .kdc, .orf, .mrw, .pef, .crw, .iiq, .x3f, .capture

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.