Free webp to jpg
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Image MIME Reference
DGN

MicroStation Design File

image/x-vnd.dgn
VS

Windows Icon (Legacy MIME)

image/x-icon
ICO

A complete technical comparison of MicroStation Design File 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 DGN ICO
Transparency (Alpha) Yes Yes
Animation Support ✕ No ✕ No
Progressive Loading ✕ No ✕ No
HDR Support ✕ No ✕ No
EXIF Metadata ✕ No ✕ No
ICC Color Profile ✕ No ✕ No
MicroStation Design File
image/x-vnd.dgn
Extension
.dgn
Container Microsoft OLE Compound File (V8) / IGDS (V7)
Compression Uncompressed / OLE Structured Storage
Algorithm
None
Color Depth Indexed Color (V7), 24-bit True Color (V8)
Developed by Intergraph (Originally) / Bentley Systems (Currently)
Released 1980
Magic Bytes
D0 CF 11 E0 A1 B1 1A E1 (For V8 DGN)
Full DGN 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 DGN ICO
Chrome Chrome
✕
✓ 1
Firefox Firefox
✕
✓ 1
Safari Safari
✕
✓ 1
Edge Edge
✕
✓ 12
IE IE (Legacy)
✕
✓
DGN

DGN Strengths

  • Exceptionally robust at handling massive, coordinate-heavy infrastructure models that would frequently crash older versions of competing CAD software
  • Deeply entrenched as the absolute standard format for many global departments of transportation and civil engineering firms
  • V8 architecture supports boundless design plane coordinates, eliminating the physical scaling limitations of V7
Limitations
  • Deeply proprietary format requiring complex third-party libraries (like the ODA SDK) to parse or write programmatically outside of the Bentley ecosystem
  • V8's reliance on the archaic Microsoft OLE Compound File container makes file introspection cumbersome
  • Cannot be rendered natively in web browsers without converting to WebGL/Canvas formats or SVG
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

DGN
Use DGN when…
  • Civil Engineering and Plant Design
  • Large-scale Architecture and Construction (AEC)
  • 2D/3D Infrastructure Modeling
ICO
Use ICO when…
  • Website Favicons (favicon.ico)
  • Windows Application Executable Icons (.exe)
  • Desktop Shortcut Icons

More comparisons

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