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AGENTS.md

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+# CLAUDE.md
+
+This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.
+
+## Project Overview
+
+Chrome is a high-performance C++17 port of negfix8, a tool for processing scanned color negative film. It inverts and color-corrects 16-bit linear Rec.709 TIFF images from film scanners.
+
+## Build Commands
+
+```bash
+# Configure and build
+cmake -B build/ -S .
+cd build && make
+
+# The executable is built at build/chrome
+```
+
+**Dependencies:** OpenCV (core, imgproc, imgcodecs), OpenMP (optional, for parallelization)
+
+## Testing
+
+Manual testing only. Compare output against reference files in `test_data/`:
+- `test_data/test_input.tiff` - Sample input scan
+- `test_data/test_expected.tiff` - Reference output from original negfix8
+- `test_data/current_output.tiff` - Current implementation output
+
+```bash
+./build/chrome -i test_data/test_input.tiff -o test_data/current_output.tiff
+# Then visually compare or diff against test_data/test_expected.tiff
+```
+
+## Usage
+
+```bash
+./chrome -i input.tif [-o output.tif] [flags]
+
+Flags:
+  -g <val>    Set gamma (default 2.15)
+  -cs         Enable contrast stretching
+  -sat        Enable saturation boost (+20%)
+  -m          Mirror image horizontally
+  -r <N>      Binning (scale down by 1/N)
+  -c <file>   Create profile and save to file (exits after)
+  -u <file>   Use existing profile
+```
+
+## Architecture
+
+Single-file implementation in `main.cpp` with this pipeline:
+
+1. **Settings/Profile structs** - CLI options and image analysis data
+2. **Image analysis** (`analyzeImage`) - Finds min/max per channel after shave+blur preprocessing
+3. **Profile save/load** - Stores derived gamma corrections and offset values
+4. **LUT generation** (`generateLUTs`) - Creates 65536-entry lookup tables for each channel using OpenMP
+5. **Pixel processing** - Applies LUTs in parallel via OpenMP
+6. **Post-processing** - Optional saturation boost, contrast stretch, mirror
+7. **Output** - Writes LZW-compressed TIFF
+
+The core algorithm inverts negative film by dividing film base values by pixel values, applies per-channel gamma correction to neutralize orange mask, then applies global gamma.