Free webp to jpg
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Image MIME Reference
DNG

Adobe Digital Negative

image/x-adobe-dng
VS

Windows Icon (Legacy MIME)

image/x-icon
ICO

A complete technical comparison of Adobe Digital Negative and Windows Icon (Legacy MIME) — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.

ICO wins on browser support

Feature Support

Feature DNG ICO
Transparency (Alpha) Yes Yes
Animation Support ✕ No ✕ No
Progressive Loading ✕ No ✕ No
HDR Support Yes ✕ No
EXIF Metadata Yes ✕ No
ICC Color Profile Yes ✕ No
Adobe Digital Negative
image/x-adobe-dng
Extension
.dng
Container TIFF/EP
Compression Lossless JPEG / Deflate / Lossy JPEG (DNG 1.4+)
Algorithm
Lossless JPEG (Standard)Lossy JPEG (Compression option)Uncompressed
Color Depth 12-bit, 14-bit, 16-bit, 32-bit (Floating Point HDR)
Developed by Adobe Systems
Released 2004
Magic Bytes
49 49 2A 00 or 4D 4D 00 2A
Full DNG reference →
Windows Icon (Legacy MIME)
image/x-icon
Extension
.ico
Container ICO Directory Structure
Compression Uncompressed (DIB/BMP) / Deflate (Embedded PNG)
Algorithm
NoneDeflate (via PNG)
Color Depth 1-bit, 4-bit, 8-bit, 24-bit (True Color), 32-bit (RGBA)
Developed by Microsoft Corporation
Released 1985
Magic Bytes
00 00 01 00
Full ICO reference →

Browser Support Comparison

Browser DNG ICO
Chrome Chrome
✕
✓ 1
Firefox Firefox
✕
✓ 1
Safari Safari
✕
✓ 1
Edge Edge
✕
✓ 12
IE IE (Legacy)
✕
✓
DNG

DNG Strengths

  • Openly documented specification guarantees long-term archival accessibility, freeing photographers from proprietary manufacturer lock-in
  • Lossless compression algorithms often result in files 15-20% smaller than uncompressed proprietary raw formats
  • Natively supported by modern smartphone operating systems (iOS and Android) for high-end mobile photography
Limitations
  • Conversion from proprietary raw to DNG takes processing time and can strip specific, proprietary manufacturer metadata (like active D-Lighting or in-camera lens corrections)
  • File sizes are massive compared to standard JPEGs or HEIC files
  • Cannot be rendered natively in web browsers without server-side processing or WebAssembly decoders
ICO

ICO Strengths

  • Universally supported by every web browser in existence for website favicons
  • Packs multiple resolutions into a single file, eliminating the need to serve different files for the taskbar vs. the desktop
  • Modern support for embedded PNGs (since Windows Vista) allows for excellent 32-bit transparency (alpha channels) and drastically reduced file sizes
Limitations
  • Internal file structure is convoluted due to decades of legacy cruft, such as the requirement for BMP data to lack a standard file header but double the height property for an archaic XOR/AND mask
  • Larger file size compared to a single optimized PNG or SVG, as it literally stores the same image multiple times at different scales
  • The MIME type landscape is highly fragmented (x-icon vs. vnd.microsoft.icon), causing occasional caching or strict-MIME validation errors on restrictive servers

When to choose which format

DNG
Use DNG when…
  • Digital Photography Archival
  • Mobile Raw Capture (iOS ProRAW / Android Camera2 API)
  • Cross-Platform Raw Editing Workflows
ICO
Use ICO when…
  • Website Favicons (favicon.ico)
  • Windows Application Executable Icons (.exe)
  • Desktop Shortcut Icons

More comparisons

DNG vs ACES → ICO vs ACES → DNG vs APNG → ICO vs APNG → DNG vs AVCI → ICO vs AVCI → DNG vs AVCS → ICO vs AVCS → DNG vs AVIF → ICO vs AVIF → All comparisons →
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