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Image MIME Reference
Nikon-NEF

Nikon Electronic Format

image/x-nikon-nef
VS

Portable Graymap

image/x-portable-graymap
PGM

A complete technical comparison of Nikon Electronic Format and Portable Graymap — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.

Equal browser support

Feature Support

Feature Nikon-NEF PGM
Transparency (Alpha) ✕ No ✕ No
Animation Support ✕ No ✕ No
Progressive Loading ✕ No ✕ No
HDR Support Yes Yes
EXIF Metadata Yes ✕ No
ICC Color Profile Yes ✕ No
Nikon Electronic Format
image/x-nikon-nef
Extension
.nef
Container TIFF
Compression Uncompressed / Lossless Compressed / Lossy Compressed (High Efficiency)
Algorithm
NoneNikon Proprietary LosslessNikon High Efficiency Lossy
Color Depth 12-bit (Per Channel), 14-bit (Per Channel)
Developed by Nikon Corporation
Released 1999
Magic Bytes
49 49 2A 00 or 4D 4D 00 2A
Full Nikon-NEF reference →
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)
Full PGM reference →

Browser Support Comparison

Browser Nikon-NEF PGM
Chrome Chrome
✕ ✕
Firefox Firefox
✕ ✕
Safari Safari
✕ ✕
Edge Edge
✕ ✕
IE IE (Legacy)
✕ ✕
Nikon-NEF

Nikon-NEF Strengths

  • Retains maximum sensor data, allowing extreme recovery of highlights and shadows that would be permanently lost in a JPEG
  • White balance, sharpening, and color profiling are saved as metadata instructions rather than 'baked in', meaning they can be completely altered in post-production without degrading the image
  • Embeds a high-quality JPEG preview inside the raw file for rapid culling and viewing
Limitations
  • Proprietary format means it requires constant updates to raw processing engines every time Nikon releases a new camera model
  • Produces very large file sizes (often 20MB to 50MB+ per image depending on sensor resolution and bit-depth)
  • Cannot be directly embedded into web pages or used in standard HTML/CSS contexts
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

Nikon-NEF
Use Nikon-NEF when…
  • Professional Digital Photography
  • Non-destructive Image Post-Processing
  • High Dynamic Range (HDR) Imaging Archival
PGM
Use PGM when…
  • Computer Vision and Machine Learning Pre-processing
  • Scientific and Medical Image Processing
  • Unix/Linux Command-Line Image Pipelines

More comparisons

Nikon-NEF vs ACES → PGM vs ACES → Nikon-NEF vs APNG → PGM vs APNG → Nikon-NEF vs AVCI → PGM vs AVCI → Nikon-NEF vs AVCS → PGM vs AVCS → Nikon-NEF vs AVIF → PGM vs AVIF → All comparisons →
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