ACES

ACES Image Container File

image/aces Released 2013 · by Academy of Motion Picture Arts and Sciences (AMPAS) / SMPTE

The ACES Image Container File (conforming to SMPTE ST 2065-4) is a professional-grade image storage format based on the OpenEXR specification. It is designed to accurately represent high-dynamic-range, scene-linear image data and associated metadata for the motion picture industry.

Professional Transparency ✦ HDR Production Ready

Technical Specifications

MIME Type

image/aces

Extensions

.exr

Container

OpenEXR (SMPTE ST 2065-4)

Compression

Lossless & Uncompressed

Algorithms

PIZZIPRLEB44Uncompressed

Color Depth

16-bit (Half-float), 32-bit (Float)

Metadata

None

Capabilities

Transparency

Animation

Progressive Loading

Alpha Channel

HDR Support

Official Specification

Aliases: image/x-exr

Magic Bytes & HTTP Headers

File Signature (Magic Bytes)

76 2F 31 01

ASCII: v/1.

HTTP Headers

Content-Type: image/aces

HTML Accept Attribute

accept="image/aces, .exr"

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

Industry standard for high-end visual effects, compositing, and color grading
Supports 16-bit half-float data, accurately capturing immense dynamic range without clipping
Standardized by SMPTE (ST 2065-4) to guarantee universal color interoperability across different post-production facilities

Limitations

Considerably larger file sizes than conventional consumer image formats
Completely unsupported in web browsers and most standard desktop viewers
Requires specialized compositing or color grading software to interpret and view the scene-linear data correctly

Developer Code Snippets

import magic
print(magic.from_file('file.exr', mime=True)) # Outputs 'image/aces' or 'image/x-exr'

const FileType = require('file-type');
const type = await FileType.fromFile('file.exr');
console.log(type.mime); // image/aces

import "net/http"

mimeType := http.DetectContentType(fileBytes)
fmt.Println(mimeType) // Note: Standard net/http may default to application/octet-stream for EXR

$mime = mime_content_type('file.exr');
echo $mime; // image/aces

File Detection Steps

How to programmatically detect a image/aces file by reading its raw bytes:

1 Check first 4 bytes for OpenEXR signature (76 2F 31 01)
2 Read the next 4 bytes to check the version field and multipart/long-name flags
3 Verify presence of SMPTE ST 2065-4 specific metadata attributes

Software Support

N

Nuke

D

DaVinci Resolve

A

Autodesk Maya

A

Adobe After Effects

B

Blender

Conversion Tools

Share & Embed

Markdown Badge

[![ACES Format](https://freewebptojpg.com/mime/image/aces/badge.svg)](https://freewebptojpg.com/mime/image/aces)

Interactive iframe Widget

<iframe src="https://freewebptojpg.com/mime/image/aces/embed" width="100%" height="280" style="border:1px solid #cbd5e1;border-radius:8px;" title="ACES Specs"></iframe>

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/aces.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 the magic byte for image/aces?

ACES image containers utilize the OpenEXR format, meaning the first four bytes are always 76 2F 31 01 in hex, which corresponds to 'v/1.' in ASCII.

Is image/aces supported in web browsers?

No, image/aces (OpenEXR) is an industry format used for high-end visual effects and color grading. It is not natively supported by any web browser.

What is the difference between an ACES file and a standard OpenEXR file?

While both use the EXR file structure, an ACES Image Container File explicitly conforms to SMPTE ST 2065-4, restricting certain parameters and mandating specific colorimetries (like ACES2065-1) and metadata attributes for consistency in professional pipelines.