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