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Image MIME Reference
BMP

Windows Bitmap (Legacy Windows MIME Alias)

image/x-windows-bmp
VS

Computer Graphics Metafile

image/cgm
CGM

A complete technical comparison of Windows Bitmap (Legacy Windows MIME Alias) and Computer Graphics Metafile — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.

BMP wins on browser support

Feature Support

Feature BMP CGM
Transparency (Alpha) Yes Yes
Animation Support ✕ No ✕ No
Progressive Loading ✕ No ✕ No
HDR Support ✕ No ✕ No
EXIF Metadata ✕ No ✕ No
ICC Color Profile Yes Yes
Windows Bitmap (Legacy Windows MIME Alias)
image/x-windows-bmp
Extension
.bmp.dib
Container DIB (Device-Independent Bitmap)
Compression Uncompressed / Run-Length Encoding (RLE)
Algorithm
NoneRLE4RLE8
Color Depth 1-bit (Monochrome), 4-bit (16 colors), 8-bit (256 colors), 16-bit (High Color), 24-bit (True Color), 32-bit (True Color with Alpha)
Developed by Microsoft Corporation
Released 1985
Magic Bytes
42 4D
Full BMP reference →
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 →

Browser Support Comparison

Browser BMP CGM
Chrome Chrome
✓ 1
 ✕
Firefox Firefox
✓ 1
 ✕
Safari Safari
✓ 1
 ✕
Edge Edge
✓ 12
 ✕
IE IE (Legacy)
✓
 ✕
BMP

BMP Strengths

  • Universally supported by all major operating systems and modern web browsers
  • Maintains perfect, lossless fidelity because pixel data is stored without lossy compression artifacts
Limitations
  • Massive file size overhead due to a lack of modern compression algorithms
  • Legacy MIME strings like 'image/x-windows-bmp' can trigger validation warnings in strict security or API environments if unhandled
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

When to choose which format

BMP
Use BMP when…
  • Legacy Windows Desktop Registry Associations
  • Older Enterprise Intranet Applications
  • Windows Graphics Archival
CGM
Use CGM when…
  • Technical Illustrations
  • Aerospace & Defense (S1000D)
  • CAD/CAM
  • Geophysics

More comparisons

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