What is MIME type "image/png+json"?

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

image/png+json is a hybrid MIME type. It embeds a standard PNG image with extra JSON data. This extra data holds metadata that can include animation details, layer information, or drawing instructions.

Developers use the +json suffix to signal that besides image data, the file carries structured, human-readable information. This approach lets applications work with both binary image content and flexible metadata.

Main use case: Combines visual content with descriptive data for enhanced editing or animation.
Supports tools like Piskel canvas for pixel art creation.
Maintains compatibility for standard image viewers while offering extra features for specialized software.

For further technical details on MIME types and their structure, consider exploring more on MIME types.

Associated file extensions

.piskel

Usage Examples

HTTP Header

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


    Content-Type: image/png+json

HTML

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


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

Associated file extensions

.piskel

FAQs

What is the image/png+json MIME type used for?

The image/png+json type typically represents a file format that bundles standard PNG image data with JSON metadata. It is most commonly associated with the Piskel pixel art editor (saving as .piskel files), allowing the software to store animation frames, layers, and color palettes alongside the visual data.

Can I display image/png+json files directly in a web browser?

No, standard web browsers like Chrome or Firefox cannot display image/png+json files using a standard <img> tag. To display the content on a website, you must export the project as a standard image/png or image/gif using the original creation tool.

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

To ensure your Apache server sends the correct headers for Piskel files, add the following line to your .htaccess file or main configuration: AddType image/png+json .piskel. This helps client applications identify the file structure immediately.

How do I add support for image/png+json in Nginx?

You should update your mime.types file or the types block in your nginx.conf. Add the line image/png+json piskel; to map the extension to the MIME type, ensuring the server delivers the content with the correct Content-Type header.

Why can't I open a .piskel file in Photoshop or Paint?

Standard image editors expect binary image formats like JPEG or PNG, but image/png+json is a structured data format containing JSON text. You need to open the file in the Piskel application and export it as a standard image file to edit it in other software.

What does the "+json" suffix mean in this MIME type?

The +json suffix is a naming convention indicating that the file is based on JavaScript Object Notation. It signals to developers and browsers that the file contains structured text data that can be parsed by JSON parsers, distinguishing it from pure binary image formats.

Is image/png+json a standard IANA MIME type?

No, image/png+json is not a widely standardized type in the IANA registry like image/png. It is considered a vendor-specific or experimental type used primarily by specific applications like Piskel to handle project states that require more data than a flat image.

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.