NegPy

NegPy turns scans of film negatives and slides into finished pictures. I wrote it because I wanted a tool made for film scans that does more than invert them. It models film and photographic paper, and adds the conveniences of a lab scanner. It is written in Python and runs on Linux, macOS and Windows.

The User Guide covers every panel and control (the ⓘ on each panel opens it in the app). PIPELINE.md explains the math.

Features

Conversion

• The orange mask is removed from each channel's own sensitometry: no camera profiles, no border color picking.
• The print is built in density space on an H&D curve (toe, straight section, shoulder) and graded in ISO-R points like darkroom paper.
• Auto Density and Auto Grade meter each frame to adjustable targets.
• Paper profiles from Ilford, Kodak, Foma and Fuji datasheets.
• Color negative, B&W and slide modes. Slides open as captured, with optional normalization for faded film and HDR merging of bracketed exposures.

Rolls

• The library is a list of rolls: imported folders, or virtual rolls built from any frames.
• Roll-wide defaults for film mode, crop, calibration, metering, raw decode, lens and metadata, with per-frame overrides.
• Roll Analysis gives every frame of a roll, or of a scene within it, the same baseline.
• Keep/reject triage, half-frame splitting, stitching, and search by metadata or (opt-in) content.

Capture

• Film scanners: Plustek OpticFilm 8200i SE and 8100 V2 over USB, Nikon Coolscan, Reflecta, Pacific Image, and anything SANE supports.
• Tethered camera scanning (macOS and Linux), including narrowband RGB captures with a Scanlight and a sub-pixel Trichrome merge (guide).
• Flat-field correction, sensor calibration for narrowband light, and lens correction read from the file.
• Camera RAWs, TIFF, DNG, JPEG XL and scanner formats such as Pakon, Coolscan NEF, Flextight FFF and Noritsu.

Editing

• Dodge and burn with polygon, oval and card-edge masks, each with its own strength, feather, contrast grade and tone limit.
• Dust, hair and scratch removal: automatic, from the IR channel (NegPy or OpenICE method), or painted, keeping the film grain.
• Darkroom tools: test strips, ring-around, step wedge, zone overlay, spot densitometer and zone placement.
• Contrast mask, tilt and swing, edge burn, filed carrier and print mats.
• Lith, cyanotype and toners for B&W.
• GPU rendering (Vulkan, Metal or DX12) with a CPU fallback that gives the same result.

Output

• ICC color management, monitor profile detection and soft proofing.
• Export to JPEG, TIFF, PNG, WebP and JPEG XL, with borders, presets, contact sheets and filename templates.
• A flat 16-bit TIFF master for other editors, or a linear export that skips the pipeline.
• Gear and capture metadata written to EXIF and XMP.

Your data

• Non-destructive: source files are never modified.
• Edits live in a local SQLite database keyed by file content, so files can move. Optional .negpy sidecars sit next to the scans.
• Undo history and named work prints survive a restart.
• Keyboard shortcuts can be remapped.

Getting started

Download the build for your OS from the Releases page. NegPy then updates itself from an Update Available notice.

To build from source, see CONTRIBUTING.md.

The builds are not signed, so expect a warning on first run.

Linux

Make the .AppImage executable with chmod +x and run it.

Optional, for SANE and camera scanning:

sudo apt install libsane        # Debian/Ubuntu
sudo pacman -S sane libgphoto2  # Arch

Nix

nix run github:marcinz606/NegPy

Or add it as a flake input:

{
  inputs.negpy.url = "github:marcinz606/NegPy";
  outputs = { self, nixpkgs, negpy, ... }: {
    # negpy.packages.<system>.default
  };
}

macOS

1. Open the .dmg and drag NegPy to /Applications.
2. Run xattr -cr /Applications/NegPy.app in Terminal.
3. Launch it.

Optional, for SANE and camera scanning (Homebrew):

brew install sane-backends libgphoto2

To build the DMG, set NEGPY_MACOS_ARCH=x86_64 (Intel) or NEGPY_MACOS_ARCH=arm64 (Apple Silicon).

Windows

Run the installer past the warnings.

Plustek OpticFilm scanners need the WinUSB driver, installed with Zadig in place of the SilverFast driver. See PLUSTEK_WINDOWS.md. Camera scanning is not available on Windows.

Data location

Everything is in Documents/NegPy. On Windows, if that folder is blocked, NegPy asks for another and suggests Local AppData. NEGPY_USER_DIR overrides both.

• edits.db: your edits.
• settings.db: app settings.
• cache/: thumbnails. Safe to delete.
• export/: default export folder.
• icc/: paper and printer profiles.
• override.toml: startup overrides (below).

Troubleshooting

If NegPy crashes on startup or renders wrong, edit override.toml (written on first run). Most [performance] values are also in Preferences (Ctrl + ,), but the file wins.

[rendering]
# Options: "auto", "vulkan" (Linux/Win), "dx12" (Win), "metal" (macOS), "cpu"
backend = "vulkan"

[display]
# Qt scene-graph backend. Options: "auto", "vulkan", "d3d12", "metal", "opengl", "software"
qt_rhi_backend = "auto"

# Window system plugin (Linux only). Options: "auto", "xcb", "wayland"
qt_platform = "auto"

[performance]
# Cap GPU texture size in pixels — useful on low-VRAM cards. "auto" = no limit.
max_texture_size = "auto"

# Force HQ preview on/off. Uncomment to override saved preference.
# force_hq_preview = false

# Long edge of the interactive preview in pixels (512-8192). Higher is a sharper
# canvas and more VRAM per frame.
# preview_render_size = 1600

# Preview cache size — keeps recently-viewed photos in memory for instant navigation.
# Lower these on low-RAM machines. Uncomment to override defaults (~1.2 GB / 8 photos).
# preview_cache_max_bytes = 1200000000
# preview_cache_max_entries = 8

[logging]
# "debug", "info", "warning", "error"
level = "info"

backend = "cpu" turns GPU rendering off if the GPU backend crashes.

More

• Roadmap
• Changelog
• Contributing

License

GPL-3.

Support

If you like NegPy, buy me a roll of film so I have more test data :)