Free webp to jpg
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Image MIME Reference
BMP

Windows Bitmap (Legacy Windows MIME Alias)

image/x-windows-bmp
VS

JPEG 2000 Codestream

image/j2c
J2C

A complete technical comparison of Windows Bitmap (Legacy Windows MIME Alias) and JPEG 2000 Codestream — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.

BMP wins on browser support

Feature Support

Feature BMP J2C
Transparency (Alpha) Yes Yes
Animation Support ✕ No ✕ No
Progressive Loading ✕ No Yes
HDR Support ✕ No Yes
EXIF Metadata ✕ No ✕ No
ICC Color Profile Yes ✕ No
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 →
JPEG 2000 Codestream
image/j2c
Extension
.j2c.j2k.jpc
Container None (Raw Bitstream)
Compression JPEG 2000 (Discrete Wavelet Transform) / Lossless / Lossy
Algorithm
Discrete Wavelet Transform (DWT)
Color Depth 8-bit, 10-bit, 12-bit, 16-bit (Per Channel)
Developed by Joint Photographic Experts Group (JPEG)
Released 2000
Magic Bytes
FF 4F FF 51
Full J2C reference →

Browser Support Comparison

Browser BMP J2C
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
J2C

J2C Strengths

  • Provides state-of-the-art wavelet compression for high-end professional workflows (Digital Cinema)
  • Allows for highly efficient progressive decoding (by resolution or quality layer) natively within the stream
  • Supports lossless mathematical compression and high bit-depths (up to 16-bit per channel) natively
Limitations
  • Lacks a standard container to store color space info or metadata, requiring external systems (like MXF or DICOM) to map colors correctly
  • Extremely computationally expensive to encode and decode compared to standard DCT-based JPEG
  • Zero web browser support

When to choose which format

BMP
Use BMP when…
  • Legacy Windows Desktop Registry Associations
  • Older Enterprise Intranet Applications
  • Windows Graphics Archival
J2C
Use J2C when…
  • Digital Cinema Packages (DCP)
  • Medical Imaging (DICOM Payloads)
  • Professional Broadcast and Archiving
  • Embedded Hardware Encoding

More comparisons

BMP vs ACES → J2C vs ACES → BMP vs APNG → J2C vs APNG → BMP vs AVCI → J2C vs AVCI → BMP vs AVCS → J2C vs AVCS → BMP vs AVIF → J2C vs AVIF → All comparisons →
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