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Image MIME Reference
CGM

Computer Graphics Metafile

image/cgm
VS

DirectDraw Surface

image/vnd.ms-dds
DDS

A complete technical comparison of Computer Graphics Metafile and DirectDraw Surface — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.

Equal browser support

Feature Support

Feature CGM DDS
Transparency (Alpha) Yes Yes
Animation Support ✕ No ✕ No
Progressive Loading ✕ No ✕ No
HDR Support ✕ No Yes
EXIF Metadata ✕ No ✕ No
ICC Color Profile Yes ✕ No
Computer Graphics Metafile
image/cgm
Extension
.cgm
Container CGM
Compression Uncompressed / Binary / Character / Clear Text
Algorithm
Deflate (in some WebCGM profiles)
Color Depth 8-bit, 16-bit, 24-bit, 32-bit
Developed by ISO / IEC
Released 1987
Magic Bytes
00 20 (Binary) / 42 45 47 49 4E 20 4D 45 54 41 46 49 4C 45 (Clear Text)
Full CGM reference →
DirectDraw Surface
image/vnd.ms-dds
Extension
.dds
Container DirectDraw Surface
Compression Block Compression (BC1-BC7) / DXTC / S3TC / Uncompressed (RGBA, Floating-Point)
Algorithm
DXT1-DXT5BC1-BC7ASTC / ETC2 (Extended)
Color Depth 8-bit, 16-bit, 24-bit, 32-bit (RGBA), 16-bit/32-bit Floating Point (HDR)
Developed by Microsoft Corporation
Released 1999
Magic Bytes
44 44 53 20
Full DDS reference →

Browser Support Comparison

Browser CGM DDS
Chrome Chrome
✕ ✕
Firefox Firefox
✕ ✕
Safari Safari
✕ ✕
Edge Edge
✕ ✕
IE IE (Legacy)
✕ ✕
CGM

CGM Strengths

  • Strictly standardized by ISO, ensuring long-term archiving and cross-platform compatibility in engineering
  • Excellent support for rich metadata, hyperlinks, and technical hotspots via the WebCGM profile
  • Can store complex 2D geometry, rasters, and text in a single lightweight file
Limitations
  • Multiple encoding schemes (Binary, Character, Clear Text) make parser development difficult
  • Zero native support in modern web browsers without third-party plugins
  • Largely replaced by SVG for general-purpose 2D vector graphics on the web
DDS

DDS Strengths

  • Massively reduces VRAM footprint and memory bandwidth usage because the GPU decodes the block compression in hardware
  • Encapsulates complex texture arrays, volume textures, cubemaps, and entire mipmap chains within a single, highly structured file
  • Supports high-dynamic-range (HDR) floating-point data for modern physically based rendering (PBR)
Limitations
  • Block compression algorithms (like DXT) are lossy and can introduce ugly blocky artifacts, especially in smooth gradients or normal maps if not tuned properly
  • Files are generally larger on the physical hard drive than highly compressed formats like PNG or WebP
  • Zero support in web browsers or standard consumer image viewers

When to choose which format

CGM
Use CGM when…
  • Technical Illustrations
  • Aerospace & Defense (S1000D)
  • CAD/CAM
  • Geophysics
DDS
Use DDS when…
  • Real-Time 3D Game Textures
  • DirectX and Vulkan Rendering Pipelines
  • Skyboxes and Environment Cubemaps
  • Volume Textures (3D Textures)

More comparisons

CGM vs ACES → DDS vs ACES → CGM vs APNG → DDS vs APNG → CGM vs AVCI → DDS vs AVCI → CGM vs AVCS → DDS vs AVCS → CGM vs AVIF → DDS vs AVIF → All comparisons →
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