Image MIME Reference
BTIF
Bank Telecommunications Image Format
image/prs.btif
VS
Windows Icon (Legacy MIME)
image/x-icon
ICO
A complete technical comparison of Bank Telecommunications Image Format and Windows Icon (Legacy MIME) — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.
ICO wins on browser support
Feature Support
| Feature | BTIF | ICO |
|---|---|---|
| Transparency (Alpha) | ✕ No | Yes |
| Animation Support | ✕ No | ✕ No |
| Progressive Loading | ✕ No | ✕ No |
| HDR Support | ✕ No | ✕ No |
| EXIF Metadata | ✕ No | ✕ No |
| ICC Color Profile | ✕ No | ✕ No |
Bank Telecommunications Image Format
image/prs.btif
Extension
.btif.btf
Container
Proprietary Check Image Container
Compression
Lossy (JPEG-based) / Lossless (TIFF-based)
Algorithm
JPEGTIFF-variant
Color Depth
1-bit (B&W), 8-bit (Grayscale)
Developed by
NationsBank (Bank of America) / Ben Simon
Released
1998
Magic Bytes
Unknown (Proprietary container)
Windows Icon (Legacy MIME)
image/x-icon
Extension
.ico
Container
ICO Directory Structure
Compression
Uncompressed (DIB/BMP) / Deflate (Embedded PNG)
Algorithm
NoneDeflate (via PNG)
Color Depth
1-bit, 4-bit, 8-bit, 24-bit (True Color), 32-bit (RGBA)
Developed by
Microsoft Corporation
Released
1985
Magic Bytes
00 00 01 00
Browser Support Comparison
| Browser | BTIF | ICO |
|---|---|---|
|
|
✕ |
✓ 1
|
|
|
✕ |
✓ 1
|
|
|
✕ |
✓ 1
|
|
|
✕ |
✓ 12
|
|
|
✕ |
✓
|
BTIF
BTIF Strengths
- Allowed early digital archiving and web-based transmission of cleared bank checks
- Encapsulated both image data and ASCII transaction metadata in a single file
Limitations
- Completely proprietary and obsolete format
- Lacks native support in modern operating systems and image viewers
- Requires legacy plugins or specialized bio-format readers (like ImageC) to decode
ICO
ICO Strengths
- Universally supported by every web browser in existence for website favicons
- Packs multiple resolutions into a single file, eliminating the need to serve different files for the taskbar vs. the desktop
- Modern support for embedded PNGs (since Windows Vista) allows for excellent 32-bit transparency (alpha channels) and drastically reduced file sizes
Limitations
- Internal file structure is convoluted due to decades of legacy cruft, such as the requirement for BMP data to lack a standard file header but double the height property for an archaic XOR/AND mask
- Larger file size compared to a single optimized PNG or SVG, as it literally stores the same image multiple times at different scales
- The MIME type landscape is highly fragmented (x-icon vs. vnd.microsoft.icon), causing occasional caching or strict-MIME validation errors on restrictive servers
When to choose which format
BTIF
Use BTIF when…
- Bank Check Archiving (Legacy)
- Financial Transaction Records
ICO
Use ICO when…
- Website Favicons (favicon.ico)
- Windows Application Executable Icons (.exe)
- Desktop Shortcut Icons