AutoCrop for Lightroom Classic: User Guide

AutoCrop automatically detects scan masks and film borders on scanned analog photos and removes them with a non-destructive crop, in batch, directly inside Lightroom Classic. It works with B&W negatives, color negatives (C-41, including special film bases such as Harman Phoenix), and positives/slides, scanned on flatbeds, film scanners, or with a camera.

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Requirements

• Adobe Lightroom Classic 10 or newer (tested with 13.x)
• macOS (Apple Silicon or Intel) or Windows 10/11
• No additional software required. The detection engine is bundled with the plugin

Installation

nzip the download and place the AutoCrop.lrplugin folder somewhere permanent (e.g. your Pictures folder).

n Lightroom Classic, open File → Plug-in Manager.

lick Add, select the AutoCrop.lrplugin folder, then click Done.

That's it. No installers, no command line.

Quick Start

Convert negatives first. If you shoot negatives and use a converter such as Negative Lab Pro, run the conversion before* cropping. AutoCrop works on unconverted negatives too, but detection quality is tuned for converted images and positives. Results on raw negatives may be poor.

elect the photos you want to crop (Library module).

pen Library → Plug-in Extras → AutoCrop – Remove Scan Borders… (also available under File → Plug-in Extras).

eave the defaults (Auto-Detect, Border Buffer 0 %, Aspect Ratio Free) and click Apply.

progress dialog shows each photo being processed. When it finishes, a summary lists how many photos were cropped and which ones were skipped, with reasons.

Every crop is a normal Lightroom crop: open the Develop module to fine-tune or undo any result at any time. Your original files are never modified.

Dialog Options

Option	What it does
Film Type	Which border type to expect. Auto-Detect (recommended) classifies the border from the image itself. Manual choices: B&W Negative (bright border), Color Negative (orange/purple film base), Positive / Slide (dark border).
Border Buffer	Slider from −3 % to +3 %. 0 % crops exactly at the detected edge. Positive values keep a little border (safer); negative values crop slightly into the image.
Aspect Ratio	Free (as detected) keeps the natural frame. Or force 3:2, 1:1 (6×6), 6:7, or 4:5. The detected frame is trimmed to fit, never expanded past the border.
Overwrite existing crop	Off (default): photos that already have a crop are skipped and reported. On: their crop is reset and re-detected.
Preview (first photo)	Runs detection on the first selected photo and shows the detected frame as a green outline, along with the detected film type and a confidence percentage.

All settings are remembered, and the dialog reopens exactly as you left it, whether you clicked Apply or Cancel.

How AutoCrop Decides

• Detection runs per photo on a Lightroom-rendered preview and measures each border side independently. Thin borders, missing sides, and mixed border colors (white on one side, black on the others) are all supported.
• Every result carries a confidence score. Below 50 %, the photo is skipped and reported instead of being cropped wrongly. AutoCrop never guesses.
• Rotated and mirrored scans are handled automatically.

Troubleshooting

The plugin writes a log to your Documents folder: AutoCropLog.txt. If you contact support, please attach this file.

Message / problem	Cause	What to do
Skipped: uncertain detection (XX%)	No clear border found: an unconverted negative, a borderless digital photo, or a very unusual border	Convert negatives first; crop manually; or set Film Type manually and retry
Skipped: already cropped	The photo already has a crop and Overwrite is off	Enable Overwrite existing crop
Skipped: crop reset not committed (try again)	Lightroom was still busy rendering when the crop reset was verified	Simply run AutoCrop again on the affected photos
A thin border strip remains	By design: AutoCrop prefers leaving a hair of border over cutting into your image	Use a negative Border Buffer, or fine-tune in Develop
One side is cropped slightly too deep	Image content near the edge closely matches the border tone (dark shadows next to black film rebate)	Use a positive Border Buffer, or fine-tune in Develop
Dialog or crop misbehaves right after installing	Lightroom caches plugin code	Restart Lightroom once after installation or updates

Known Limitations

• Convert negatives before cropping. Detection on unconverted negatives works but is not quality-guaranteed (the dialog reminds you of this).
• No automatic straightening. Slightly tilted film is handled by cropping deeper at the corners; the crop angle itself stays 0°. You can straighten manually in Develop afterwards.
• Sliver tolerance. On heavily layered 35 mm borders, a residual strip of up to ~0.3 % may remain — a deliberate choice: better a hair of border than lost image content.
• Photos where image content touches the frame edge with the exact tone of the border (e.g. a black shadow meeting black rebate) are fundamentally ambiguous; AutoCrop stays conservative there.