Image MIME Reference
DXF
Drawing Exchange Format
image/vnd.dxf
VS
Portable Graymap
image/x-portable-graymap
PGM
A complete technical comparison of Drawing Exchange Format and Portable Graymap — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.
Equal browser support
Feature Support
| Feature | DXF | PGM |
|---|---|---|
| Transparency (Alpha) | Yes | ✕ No |
| Animation Support | ✕ No | ✕ No |
| Progressive Loading | ✕ No | ✕ No |
| HDR Support | ✕ No | Yes |
| EXIF Metadata | ✕ No | ✕ No |
| ICC Color Profile | ✕ No | ✕ No |
Drawing Exchange Format
image/vnd.dxf
Extension
.dxf
Container
Text / Binary Container
Compression
Uncompressed (ASCII) / Uncompressed (Binary)
Algorithm
None
Color Depth
Vector (Indexed AutoCAD Colors / True Color)
Developed by
Autodesk
Released
1982
Magic Bytes
30 0D 0A 53 45 43 54 49 4F 4E (ASCII) / 41 75 74 6F 43 41 44 20 42 69 6E 61 72 79 20 44 58 46 0D 0A 1A 00 (Binary)
Portable Graymap
image/x-portable-graymap
Extension
.pgm
Container
Netpbm
Compression
Uncompressed
Algorithm
None
Color Depth
8-bit (Grayscale), 16-bit (Grayscale)
Developed by
Jef Poskanzer (Netpbm Project)
Released
1988
Magic Bytes
50 32 (ASCII) or 50 35 (Binary)
Browser Support Comparison
| Browser | DXF | PGM |
|---|---|---|
Chrome
|
✕ | ✕ |
Firefox
|
✕ | ✕ |
Safari
|
✕ | ✕ |
Edge
|
✕ | ✕ |
IE (Legacy)
|
✕ | ✕ |
DXF
DXF Strengths
- Universally supported by almost every CAD program, 3D modeler, and vector graphics editor in existence
- ASCII structure is human-readable and can be parsed or generated programmatically with relative ease
- The de facto standard for sending 2D cutting paths to CNC routers, plasma cutters, and laser engravers
Limitations
- ASCII DXF files can be enormously large and inefficient compared to binary DWG files
- The format relies heavily on legacy AutoCAD data structures, making complex 3D entity parsing extremely difficult for third-party developers
- Lacks native web browser rendering capabilities
PGM
PGM Strengths
- Extremely simple format allows custom parsers to be written from scratch in minimal time
- Supports 16-bit precision, making it highly valuable for scientific, medical, and height-map data where 8-bit precision is insufficient
- ASCII encoding ('P2') allows manual editing and visual inspection of pixel values directly within a text editor
Limitations
- Strictly limited to grayscale; cannot display color
- Lack of compression results in massive file sizes, making it entirely impractical for web delivery or consumer storage
- Does not support alpha transparency or modern metadata structures
When to choose which format
DXF
Use DXF when…
- Cross-Platform CAD Data Exchange
- CNC Machining and Laser Cutting Paths
- PCB Design Outlines
- Architectural 2D Layouts
PGM
Use PGM when…
- Computer Vision and Machine Learning Pre-processing
- Scientific and Medical Image Processing
- Unix/Linux Command-Line Image Pipelines