extracting-with-ocr

<!-- AI-RULEZ :: GENERATED FILE — DO NOT EDIT Content-Hash: blake3:3ec8b7cf60f56cbe5cc15a5a0b29d0c2f8e3cf4c3823503eb1128fb7f9ee11db Source-Hash: blake3:3fca38eb564d0ed9c9194d070fd8dec96de727edc92e82954cb4b9af52cddbaf Schema-Version: v1 --> # Extracting with OCR Use this when a document is image-based: scanned PDFs, photographed pages, screenshots, JPEG/PNG/TIFF with text. Xberg auto-OCRs raster images and auto-detects PDFs that lack a text layer. Force it on when extraction returned empty/garbled text from a PDF that "looks" textual. ## When to force OCR - Extraction returned an empty `content` field, but the file opens visually. - The PDF text layer is junk (copy-paste from a viewer produces gibberish). - You want consistent output across mixed scanned + digital PDFs. ```bash xberg extract scan.pdf --force-ocr=true xberg extract scan.pdf --ocr=true --ocr-language eng ``` If a page has an unreliable text layer, `--force-ocr=true` re-rasterizes and runs OCR on every page. ## Backends Tesseract is the default and ships with the CLI — no extra install. Other backends are opt-in: | Backend | Flag | Install | Notes | | ------------- | ------------------------------------- | ------------------------------------------------ | -------------------------------------------------------------- | | Tesseract | `--ocr-backend tesseract` (default) | bundled | Best general-purpose, 100+ languages via tessdata. | | PaddleOCR | `--ocr-backend paddle-ocr` | bundled (ONNX Runtime) | Strong on Asian scripts. Not available on WASM or Windows. | | Candle VLM | `--ocr-backend candle-trocr` (and other `candle-*`) | bundled (Candle) | Local vision OCR models (`candle-trocr`, `candle-paddleocr-vl`, `candle-glm-ocr`, `candle-deepseek-ocr`). | | VLM (hosted) | `--ocr-backend vlm` + `--vlm-model` | liter-llm provider (`--vlm-api-key`) | Multimodal LLM via liter-llm. Use when OCR fails on dense or handwritten layouts. | Pick Tesseract first. Switch only when accuracy is unacceptable. ## Language packs Tesseract uses ISO 639-2 codes. Default is `eng`. Combine with `+`: ```bash xberg extract menu.jpg --ocr=true --ocr-language "eng+deu" xberg extract bilingual.pdf --ocr-language "eng+jpn" xberg extract any.pdf --ocr-language all # all installed packs ``` Install missing packs at the OS level: ```bash # macOS brew install tesseract-lang # Debian/Ubuntu sudo apt install tesseract-ocr-deu tesseract-ocr-jpn tesseract-ocr-fra # Specific lang only sudo apt install tesseract-ocr-<iso639-2> ``` Xberg fails fast with a helpful error if you request a language pack that is not installed. Read the error — it names the missing file. ## Useful flags - `--ocr=true` — enable OCR (auto-enabled for images and scanned PDFs). - `--force-ocr=true` — OCR every page even if a text layer exists. - `--disable-ocr=true` — never OCR (extract embedded text only or fail). - `--ocr-language <lang>` — single code or `+`-joined list, or `all`. - `--ocr-backend <tesseract|paddle-ocr|vlm|candle-trocr|candle-paddleocr-vl|candle-glm-ocr|candle-deepseek-ocr>` — pick backend. - `--ocr-auto-rotate=true` — pre-rotate via the auto-rotate model. - `--acceleration <cpu|coreml|cuda|tensorrt|auto>` — ONNX accelerator for paddle-ocr / auto-rotate / layout models. ## Performance tips - Cache is on by default. Repeated extraction of the same file + config is instant. Do not pass `--no-cache=true` unless you have a reason. - For batch OCR, use `xberg batch *.pdf --ocr=true` — internal worker pool parallelizes across CPU cores. Cap with `--max-concurrent N` if memory is tight. - Raise `--target-dpi` (default 300) only for low-resolution scans. Higher DPI is slower; 200 is usually enough for printed text. - Enable `--ocr-auto-rotate=true` only when pages may be rotated; the classifier adds latency. - On Apple Silicon, `--acceleration coreml` typically beats CPU for paddle-ocr and layout detection. ## Config file alternative Long flag chains belong in `xberg.toml` — auto-discovered from cwd upward. ```toml force_ocr = true output_format = "markdown" [ocr] backend = "tesseract" language = "eng+deu" auto_rotate = true ``` Then just run: ```bash xberg extract document.pdf ``` ## Common failure modes - **"missing tessdata"** — install the language pack at OS level (see above). - **Empty content on a scanned PDF without `--force-ocr`** — the file has a bogus zero-width text layer. Re-run with `--force-ocr=true`. - **OCR on a rotated page** — add `--ocr-auto-rotate=true` or pre-rotate. - **Garbled CJK output** — ensure the right language pack is installed and passed via `--ocr-language`; consider `paddle-ocr` for Chinese/Japanese. See `references/cli-reference.md` and `references/configuration.md` in the sibling `xberg` skill for the full flag and config schema.