Pentax-PEF

Pentax Electronic File

image/x-pentax-pef Released 2003 · by Pentax (now Ricoh Imaging Company, Ltd.)

The image/x-pentax-pef MIME type represents the Pentax Electronic File (PEF) format, the proprietary raw image format utilized by Pentax (now Ricoh Imaging) digital SLR and mirrorless cameras. Built upon the standard TIFF container specification, a PEF file stores unprocessed and uncompressed (or losslessly compressed) pixel data directly from the camera's image sensor. This format preserves maximum dynamic range, color fidelity, and essential metadata (including Pentax-specific MakerNotes), allowing photographers to make extensive non-destructive edits to exposure and white balance. While newer Pentax camera models optionally allow users to save raw images directly in the open Adobe DNG format, PEF remains the historical and native standard for Pentax raw captures.

Photography & Raw Imaging ✦ HDR Production Ready

Technical Specifications

MIME Type

image/x-pentax-pef

Extensions

.pef

Container

TIFF-based (Proprietary)

Compression

Uncompressed & Proprietary Lossless

Algorithms

NonePentax Proprietary Lossless

Color Depth

12-bit (Per Channel), 14-bit (Per Channel)

Metadata

EXIF XMP ICC

Capabilities

Transparency

Animation

Progressive Loading

Alpha Channel

HDR Support

Official Specification

Aliases: image/pef

Magic Bytes & HTTP Headers

File Signature (Magic Bytes)

49 49 2A 00 (Little-endian) or 4D 4D 00 2A (Big-endian)

ASCII: II*\x00 or MM\x00*

HTTP Headers

Content-Type: image/x-pentax-pef

HTML Accept Attribute

accept="image/x-pentax-pef, .pef"

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

Retains absolute maximum sensor data, enabling massive shadow recovery and highlight protection compared to compressed in-camera JPEGs
White balance and sharpening are saved as metadata instructions rather than 'baked in', meaning they can be perfectly adjusted in post-production
Utilizes the standard TIFF container structure, making it relatively straightforward for open-source software like LibRaw to parse

Limitations

Proprietary format requires continuous updates to third-party processing software whenever Pentax releases a new camera model (unlike the open DNG format)
Produces very large file sizes compared to standard web formats
Cannot be directly embedded into web pages or used in standard HTML/CSS contexts

Developer Code Snippets

import magic
# Libmagic will identify PEF files as standard TIFFs due to the shared 49 49 2A 00 / 4D 4D 00 2A header
print(magic.from_file('photo.pef', mime=True)) # Outputs 'image/tiff'

const FileType = require('file-type');
const type = await FileType.fromFile('photo.pef');
console.log(type?.mime); // Usually resolves to 'image/tiff'. You must rely on the .pef extension for precise routing.

import (
    "bytes"
    "net/http"
    "strings"
)
// Native Go HTTP detection reads the TIFF magic bytes and returns 'image/tiff'.
// You must explicitly check the filename extension to infer Pentax PEF intent.
// isPEF := strings.HasSuffix(strings.ToLower(filename), ".pef")

$mime = mime_content_type('photo.pef');
echo $mime; // Standard PHP setups will resolve this to 'image/tiff' based on the file header.

File Detection Steps

How to programmatically detect a image/x-pentax-pef file by reading its raw bytes:

1 PEF files are built on the standard TIFF specification and therefore begin with the standard little-endian (49 49 2A 00) or big-endian (4D 4D 00 2A) magic bytes.
2 Because they share this exact header with standard TIFF files and other TIFF-based raw formats (like Nikon NEF and Canon CR2), standard MIME sniffers often misidentify PEF files as 'image/tiff'.
3 To definitively detect a PEF file programmatically, you must parse the TIFF header directories and examine the EXIF MakerNote to confirm the 'Pentax' or 'Asahi' manufacturer signature.

Software Support

P

Pentax Digital Camera Utility

A

Adobe Lightroom Classic / CC

D

Darktable

R

RawTherapee

Conversion Tools

Share & Embed

Markdown Badge

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Interactive iframe Widget

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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/pentax-pef.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 a Pentax PEF file?

A PEF (Pentax Electronic File) is a raw image format generated by Pentax digital cameras. It contains raw, unprocessed sensor data that offers significantly higher dynamic range and editing flexibility compared to standard compressed JPEGs.

How do I open a PEF file?

Because PEF is a raw format, standard web browsers and basic image viewers cannot render it natively. You must use specialized raw processing software like Pentax Digital Camera Utility, Adobe Lightroom, Capture One, Darktable, or RawTherapee.

Should I shoot in PEF or DNG on my Pentax camera?

Many modern Pentax cameras give you the option to save raw files as either PEF or DNG. While PEF is the native proprietary format, DNG (Digital Negative) is an open standard that guarantees broader software compatibility out-of-the-box without waiting for third-party raw engines to update their camera profiles.