Contrek: Vectorizing 10 Billion Pixels on a Raspberry Pi 5 with Just 4 GB RAM

说明与用途

Contrek 通过流式处理水平条带并将多边形写入磁盘，使得在 4 GB RAM 的 Raspberry Pi 5 上处理 10 十亿像素的栅格图像时，峰值内存仅为 2.42 GB。

问题

Processing extremely large raster images without loading the entire image into memory.

结果

On a Raspberry Pi 5 with 4 GB RAM, Contrek processed a 10 billion‑pixel image in 13 min 52 s, peaking at 2.42 GiB memory, producing a 21.03 GB SVG without any swap.

工作流

• 1. Install Contrek on a Raspberry Pi 5 with 4 GB RAM, 250 GB NVMe SSD, Ubuntu 24.04 ARM64 Docker container.
• 2. Prepare a 100,000 × 100,000 pixel PNG image (~900 MB compressed).
• 3. Run Contrek with horizontal stripe width of 1,000 rows.
• 4. Contrek extracts contours, reconnects across stripes, and writes polygons to disk progressively.
• 5. Monitor execution time, peak memory, and CPU usage.
• 6. Verify output SVG (~21 GB) and confirm no swap usage.

证据

Contrek can process an image in horizontal stripes, reconnecting contours across stripe boundaries and progressively writing completed polygons to disk.

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The input was a 100,000 × 100,000 pixel PNG image, containing 10 billion pixels. The compressed PNG file is about 900 MB.

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Peak process memory 2.42 GiB

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Output SVG 21.03 GB

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The process completed successfully, with zero swaps reported by GNU time.

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