What is MIME type "image/openraster"?

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

image/openraster is the official MIME type for the OpenRaster format. It is built to store layered images without losing individual elements like layers, masks, and adjustments.

This format helps graphic editors keep all editing data intact. It allows you to revisit and adjust any part of your image later. Being an open standard, it encourages compatibility among different applications.

Layer Preservation: Keeps each layer and effect separate, supporting non-destructive editing.
Interoperability: Many software tools use it to exchange detailed image data.
Open Standard: Freely available for developers and artists, fostering broader support.

Files using this MIME type usually have the extension ORA.

For more details, check out the OpenRaster homepage.

Associated file extensions

.ora

Usage Examples

HTTP Header

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


    Content-Type: image/openraster

HTML

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


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

Associated file extensions

.ora

FAQs

Which software applications support the image/openraster MIME type?

This format is primarily supported by open-source graphics editors such as Krita, GIMP, and MyPaint. Because image/openraster is an open standard designed to facilitate the exchange of layered images, these programs allow users to move projects between different applications without losing layer structure.

Can web browsers display .ora files directly?

No, major web browsers like Chrome, Firefox, and Safari do not natively render image/openraster files. To display an image on a website, you must export the project to a standard web format like image/png or image/jpeg.

How do I configure an Apache server to serve OpenRaster files?

To ensure your Apache server sends the correct Content-Type, add the following line to your .htaccess file or main configuration: AddType image/openraster .ora. This tells the server to identify files with the .ora extension as OpenRaster images.

What is the correct Nginx configuration for image/openraster?

For Nginx, you should modify your mime.types file to include the definition. Add the line image/openraster ora; within the types block, and then reload your Nginx service to apply the changes.

Why is image/openraster considered an archive format?

Under the hood, an OpenRaster file is actually a ZIP archive. It contains a stack.xml file that defines the image structure and individual PNG files representing the data for each layer, making it easy for developers to inspect or repair using standard archive tools.

Should I use image/openraster for images on my website?

No, this MIME type is intended for editing and storage of work-in-progress files containing multiple layers. These files are typically much larger than flattened images; you should always convert them to optimized formats like WebP or JPG for web use.

What happens if I rename an .ora file to .zip?

Since the file structure is based on the ZIP standard, renaming the extension to .zip allows you to open it with standard operating system tools like Windows Explorer or macOS Archive Utility. This allows you to extract specific layers manually if needed.

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.