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Fempeg

Fempeg is a Rust tool that converts Nikon NEF RAW files into processed image formats like PNG or JPEG.

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Installation

Windows

On GitHub releases, there are two versions:

1. fempeg.exe → Without ExifTool

   • Includes only some basic EXIF info (printed to bash).
   • Smaller file size (~3MB).
   • No additional dependencies required.

2. fempeg-exif.exe → With ExifTool

   • Full EXIF support, including the -i interactive TUI for searching EXIF info.
   • Larger file size (~36MB).
   • No additional dependencies required.

Download the version that fits your needs.

Unix

git clone https://github.com/SirPigari/fempeg.git
cd fempeg

• Without ExifTool:

cargo build --release

• With ExifTool:

cargo build --release --features include_exiftool

Make sure you have libraw and exiftool installed if using the include_exiftool feature.

The output binary will be in target/release/fempeg.

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Usage

Fempeg supports exporting to a wide range of image formats for maximum compatibility:

• PNG
• JPEG (or JPG)
• BMP
• GIF
• WebP
• TIFF (or TIF)
• TGA
• ICO
• HDR
• OpenEXR (or EXR)
• PNM (PBM, PGM, PPM, PAM)
• Farbfeld (or FF)
• AVIF
• QOI

Convert a single NEF to PNG (default)

fempeg ./photo.NEF

Convert a single NEF to a specific output path

fempeg photo.NEF -o ./output/photo_out.png

Convert a directory of NEFs

fempeg ./nefs -o ./out --format png

Convert to multiple formats at once

fempeg photo.NEF -o ./out -f png+jpeg

Flags

• -r, --ratio <R> → Resize output image by ratio (0 < R <= 1), default: 0.15
• -t, --threads <N> → Number of threads to use, default: number of CPU cores
• -p, --preview → Use the embedded preview image instead of full RAW processing
• -b, --brightness [VAL] → Brightness control. Accepts auto|none|<float>|<int>|<percent>%. No flag = leave as-is. -b without value => auto
• -R, --rotation <VAL> → auto to use EXIF orientation or explicit degrees (90,180,270)
• -e, --enhance → Apply a light enhancement (unsharpen + small contrast)
• -d, --debug → Enable debug output
• --sort <METHOD> → Sort input files before processing (name, numeric, size, mtime)
• -i, --info → Show EXIF info about the file, exit afterwards (interactive TUI available if using ExifTool)
• -h, --help → Show help message

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Dependencies

• libraw → RAW conversion library
• ExifTool → Metadata extraction (included in Windows fempeg-exif.exe or via --features include_exiftool on Unix)
• Windows users do not need to install any dependencies.
• All other dependencies are managed by cargo

Note: Fempeg has been tested only with Nikon NEF files.
While libraw supports most Nikon cameras, some newer or software-generated NEFs may not decode correctly.

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License

• Fempeg License
• LibRaw License
• ExifTool License