What is the MRK file format?
.mrk files contain information about the order in which graphics data should be printed or transferred from an image-capturing device (camera) to an image-processing device. .mrk files store data in plain text format. The first version of the DPOF standard defines the procedure as photo print parameters and order, typically saved as AUTPRINT.MRK in a /MISC folder on the camera's memory card.
The standard was developed in 1998 by Canon, Kodak, Fujifilm, and Matsushita (Panasonic). The DPOF 1.10 extension specification, published in 2000, defines an optional Auto Transfer file (autxfer.mrk), which specifies the structure of transferred files, and an Auto Play file (autplay.mrk) for presenting images. Presentations may also contain audio and video material. Additionally, support for printing multiple photos on a single page and a print-size attribute were introduced.
.mrk files reference JPEG images stored elsewhere on the card - they hold no image data of their own. A .mrk file defines parameters such as:
[HDR]- Header containing general information: standard version, the software that created the file, the date, and optional camera-user details.[JOB]- Information about a task, including:- Type of task: printing, data transfer, or presentation
- Task ID number
- Path to the related image file
- Additional parameters such as email address, print quality, and copy count
.mrk files are used by imaging devices - photo-printing kiosks, printing-service servers, and other devices that support the DPOF standard. They allow users to connect a camera memory card to such a device and automatically print, send via email, or view a presentation of selected photos.
Security & safety
RISK: LOWA DPOF .mrk is a tiny plain-text index with no executable content, so it is harmless to open or read. The main thing to understand is that it is NOT your photos: deleting AUTPRINT.MRK removes only the print order, not the images (which live in /DCIM). If you want the pictures, copy the JPEGs, not the .mrk.
Format details
in a nutshellPrograms that open MRK files
Windows1 app
Notepad / Notepad++
Free Right-click the AUTPRINT.MRK > Open with > Notepad to read the plain-text print order. 
macOS1 app
Linux1 app
Technical details
deep spec| Text encoding | ASCII / 8-bit character set as specified by DPOF |
| File structure | Bracketed section keywords ([HDR], [JOB]) followed by key=value lines |
| MIME type | text/plain |
| Compression | None - plain uncompressed text |
| Typical file size | Under 1 KB to a few KB depending on number of selected images |
| File identification | No binary magic bytes; identified by the [HDR] keyword and the conventional AUTPRINT.MRK filename |
| Conventional filename and path | AUTPRINT.MRK stored in the /MISC folder on the camera memory card |
| Version declaration | DPOF version number declared in the [HDR] section of the file |
| Image data | Contains no pixel data; references JPEG images in ../DCIM or ../IMAGE directories on the same card |
| Developing consortium | Canon, Kodak, Fujifilm, and Matsushita (Panasonic) |
| Supported standard versions | DPOF 1.00 (1998) and DPOF 1.10 (2000) |
| Compatible environments | DPOF-aware camera firmware, photo kiosks, printing-service servers, and any plain-text editor |
| Companion files | autxfer.mrk (auto-transfer order) and autplay.mrk (auto-play presentation), both defined in DPOF 1.10 |
| Print order capabilities | Supports copy count per image, multi-photo pages, print size, presentation slides, and email-transfer parameters |
| Released | 1998 (DPOF 1.00 specification) |
| Latest version | DPOF 1.10 (2000) |
| Open standard | Yes · royalty-free |
| Specification | en.wikipedia.org |
MRK conversions
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