Image MIME Reference
BMP
Windows Bitmap (Legacy Windows MIME Alias)
image/x-windows-bmp
VS
Khronos Texture
image/ktx
KTX
A complete technical comparison of Windows Bitmap (Legacy Windows MIME Alias) and Khronos Texture — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.
BMP wins on browser support
Feature Support
| Feature | BMP | KTX |
|---|---|---|
| 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 |
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
Khronos Texture
image/ktx
Extension
.ktx
Container
KTX (Khronos Texture 1.1)
Compression
Uncompressed / GPU Compressed (ASTC, ETC, BCn, PVRTC)
Algorithm
ASTCETC1 / ETC2BCn (DXT)PVRTCBasis Universal (in KTX2)
Color Depth
8-bit, 16-bit, 32-bit (Integer/Float)
Developed by
Khronos Group
Released
2010
Magic Bytes
AB 4B 54 58 20 31 31 BB 0D 0A 1A 0A
Browser Support Comparison
| Browser | BMP | KTX |
|---|---|---|
|
|
✓ 1
|
✕ |
|
|
✓ 1
|
✕ |
|
|
✓ 1
|
✕ |
|
|
✓ 12
|
✕ |
|
|
✓
|
✕ |
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
KTX
KTX Strengths
- Enables direct-to-GPU texture uploading, drastically reducing load times and CPU overhead in 3D applications
- Supports complex texture types natively (mipmaps, cubemaps, 3D volumes, texture arrays)
- Standardized across major Khronos APIs (OpenGL, Vulkan, WebGL) unlike vendor-specific formats like DDS
Limitations
- Requires custom JavaScript loaders to parse and display on the web
- Zero native support in consumer image viewers or 2D photo editing software
- Format fragmentation: a KTX file containing an ASTC payload will fail to render on hardware that only supports BCn compression (KTX2 and Basis Universal solve this)
When to choose which format
BMP
Use BMP when…
- Legacy Windows Desktop Registry Associations
- Older Enterprise Intranet Applications
- Windows Graphics Archival
KTX
Use KTX when…
- Real-time 3D Graphics
- WebGL / WebGPU Applications
- Mobile Games
- Virtual/Augmented Reality (VR/AR)