Free webp to jpg
EN
Image MIME Reference
DGN

MicroStation Design File

image/x-vnd.dgn
VS

Truevision TGA (Legacy MIME Alias)

image/x-tga
TGA

A complete technical comparison of MicroStation Design File and Truevision TGA (Legacy MIME Alias) — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.

Equal browser support

Feature Support

Feature DGN TGA
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 →
Truevision TGA (Legacy MIME Alias)
image/x-tga
Extension
.tga.icb.vda.vst
Container Truevision TGA Footer/Header
Compression Uncompressed / Run-Length Encoding (RLE)
Algorithm
NoneRLE
Color Depth 8-bit (Grayscale or Indexed), 16-bit (High Color), 24-bit (True Color), 32-bit (True Color with Alpha Channel)
Developed by Truevision Inc.
Released 1984
Magic Bytes
54 52 55 45 56 49 53 49 4F 4E 2D 58 46 49 4C 45 2E 00 (At the end of the file)
Full TGA reference →

Browser Support Comparison

Browser DGN TGA
Chrome Chrome
✕ ✕
Firefox Firefox
✕ ✕
Safari Safari
✕ ✕
Edge Edge
✕ ✕
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
TGA

TGA Strengths

  • Incredibly simple byte layout allows developers to write custom loaders and exporters in a few dozen lines of code, bypassing the need for heavy external libraries
  • Native support for 8-bit alpha channels ensures flawless transparency masking for real-time 3D rendering
  • Fast, predictable RLE decoding requires almost no CPU overhead compared to DEFLATE (PNG) or DCT (JPEG)
Limitations
  • RLE compression is relatively weak by modern standards, resulting in large file sizes
  • Lacks a standard magic byte header at the beginning of the file, making file-sniffing unreliable for older v1.0 files
  • Zero support in web browsers; must be converted to PNG or WebP for web delivery

When to choose which format

DGN
Use DGN when…
  • Civil Engineering and Plant Design
  • Large-scale Architecture and Construction (AEC)
  • 2D/3D Infrastructure Modeling
TGA
Use TGA when…
  • Video Game 3D Textures and Materials
  • 3D Rendering and Animation Sequences
  • Legacy Video Production Workflows

More comparisons

DGN vs ACES → TGA vs ACES → DGN vs APNG → TGA vs APNG → DGN vs AVCI → TGA vs AVCI → DGN vs AVCS → TGA vs AVCS → DGN vs AVIF → TGA vs AVIF → All comparisons →
Share this comparison