faster-paddle 0.0.1

Fast CPU OCR — PaddleOCR PP-OCRv6 tiny (lightweight), reimplemented in Rust + ONNX Runtime. ~7x faster than PaddlePaddle, self-contained wheels with models bundled.

faster-paddle

Fast, CPU-only OCR in Rust with Python bindings — a self-contained reimplementation of PaddleOCR's lightweight pipeline (PP-OCRv6 tiny detection + recognition) powered by ONNX Runtime.

• ⚡ ~7× faster than paddleocr on CPU for the same models and output.
• 📦 Self-contained — the ONNX models (~6 MB) are bundled inside the wheel. No paddlepaddle, no model downloads, no network at runtime.
• 🦀 Pure-Rust pre/post-processing (detection DB decode, minAreaRect, perspective crop, CTC decode, reading-order text reconstruction). No OpenCV.
• 🖥️ Prebuilt wheels for Linux, Windows, macOS (x86-64 + arm64).

paddleocr (PaddlePaddle, CPU)        22.7 s / image
faster-paddle (Rust + ONNXRuntime)    3.0 s / image     →  ~7.7× faster

(test image 3157×4464, AMD Ryzen 7 5800X3D; both after warm-up, same weights.)

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Install

pip install faster-paddle

Usage

import faster_paddle

# One-shot, using a shared default engine (lazily initialized):
with open("document.jpg", "rb") as f:
    result = faster_paddle.ocr(f.read())

print(result["text"])              # reading-order reconstructed text
for idx, b in result["bounds"].items():
    print(idx, b["text"], b["confidence"], b["topLeftCoord"], b["bottomRightCoord"])

Reuse an explicit engine (recommended for servers — load the models once):

from faster_paddle import OcrEngine

engine = OcrEngine(threads=None, rec_batch=6)   # threads default = physical cores

result = engine.ocr(image_bytes)                 # raw jpeg/png/webp/bmp/tiff/gif bytes
result = engine.ocr_base64(b64_string)           # base64-encoded image

Result shape

{
  "text": "full reconstructed text...",
  "bounds": {
     0: {
        "topLeftCoord":     (x1, y1),
        "bottomRightCoord": (x2, y2),
        "text":             "line text",
        "confidence":       0.97,
     },
     1: { ... },
  }
}

This matches the JSON contract of the original paddle-ocr-api service, so it is a drop-in replacement.

API

faster_paddle.ocr(image: bytes) -> dict	OCR encoded image bytes (shared default engine).
faster_paddle.ocr_base64(image_base64: str) -> dict	OCR a base64 image string.
OcrEngine(threads=None, rec_batch=None)	Construct a reusable engine.
OcrEngine.ocr(image: bytes) -> dict	OCR encoded image bytes.
OcrEngine.ocr_base64(image_base64: str) -> dict	OCR a base64 image string.

• threads: ONNX Runtime intra-op threads. Defaults to the number of physical CPU cores (SMT/logical threads tend to slow compute-bound inference down).
• rec_batch: recognition batch size (default 6).

Calls are thread-safe (serialized internally) and release the GIL during inference.

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How it works

The pipeline faithfully mirrors PaddleOCR's lightweight path:

1. Detection — resize (min-side 736, clamp max-side 4000, round to ×32), normalize (BGR mean/std), run the DB detector.
2. DB post-process — threshold 0.2, connected components, minAreaRect, box score ≥ 0.4, unclip ratio 1.4, rescale to source coordinates.
3. Sort boxes top-to-bottom / left-to-right; crop each via perspective warp.
4. Recognition — resize each crop to H=48, normalize, batch, run the CTC recognizer ([N, T, 6906]), greedy CTC decode.
5. Reconstruct reading-order text with dynamic column/line detection.

Detection matches PaddlePaddle at 96 % IoU>0.5 with 0.93 character-level similarity on the recognized text; the residual difference is ONNX-Runtime vs PaddlePaddle floating-point numerics, not the algorithm.

The bundled models are PP-OCRv6_tiny_det and PP-OCRv6_tiny_rec exported with paddle2onnx.

Building from source

pip install maturin
maturin develop --release      # build + install into the current environment
# or
maturin build --release        # produce a wheel in target/wheels/

Requires a Rust toolchain. ONNX Runtime is fetched automatically by the ort crate at build time and linked into the extension.

License

MIT