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Image MIME Reference
ACES

ACES Image Container File

image/aces
VS

Apple Icon Image

image/x-icns
Apple-ICNS

A complete technical comparison of ACES Image Container File and Apple Icon Image — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.

Equal browser support

Feature Support

Feature ACES Apple-ICNS
Transparency (Alpha) Yes Yes
Animation Support ✕ No ✕ No
Progressive Loading ✕ No ✕ No
HDR Support Yes ✕ No
EXIF Metadata ✕ No ✕ No
ICC Color Profile ✕ No Yes
ACES Image Container File
image/aces
Extension
.exr
Container OpenEXR (SMPTE ST 2065-4)
Compression Lossless / Uncompressed
Algorithm
PIZZIPRLEB44Uncompressed
Color Depth 16-bit (Half-float), 32-bit (Float)
Developed by Academy of Motion Picture Arts and Sciences (AMPAS) / SMPTE
Released 2013
Magic Bytes
76 2F 31 01
Full ACES reference →
Apple Icon Image
image/x-icns
Extension
.icns
Container Chunk-based (OSType Header)
Compression Uncompressed (Legacy) / PNG (Modern) / JPEG 2000 (Modern)
Algorithm
NoneDeflate (via embedded PNG)Wavelet (via embedded JP2)
Color Depth 1-bit (Monochrome), 4-bit, 8-bit, 24-bit (RGB), 32-bit (RGBA)
Developed by Apple Inc.
Released 2001
Magic Bytes
69 63 6E 73
Full Apple-ICNS reference →

Browser Support Comparison

Browser ACES Apple-ICNS
Chrome Chrome
✕ ✕
Firefox Firefox
✕ ✕
Safari Safari
✕ ✕
Edge Edge
✕ ✕
IE IE (Legacy)
✕ ✕
ACES

ACES Strengths

  • 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
Apple-ICNS

Apple-ICNS Strengths

  • Seamlessly handles multi-resolution scaling on macOS, perfectly serving both standard and high-DPI (Retina) displays from a single asset
  • Modern versions efficiently embed standard PNG files, making it much easier to parse the high-resolution layers than the legacy raw pixel formats
Limitations
  • Strictly bound to the Apple ecosystem; completely useless natively on Windows, Linux, or the Web
  • The internal chunking structure is notoriously messy, utilizing dozens of different undocumented, legacy OSType tags spanning 20+ years of Apple history

When to choose which format

ACES
Use ACES when…
  • Visual Effects (VFX)
  • Digital Intermediate (DI)
  • Color Grading
  • Archival
Apple-ICNS
Use Apple-ICNS when…
  • macOS Application Bundles (.app)
  • macOS Folder Customization
  • Apple Disk Image (.dmg) Styling

More comparisons

ACES vs APNG → Apple-ICNS vs APNG → ACES vs AVCI → Apple-ICNS vs AVCI → ACES vs AVCS → Apple-ICNS vs AVCS → ACES vs AVIF → Apple-ICNS vs AVIF → All comparisons →
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