/extracting-with-ocr

name: extracting-with-ocr
description: Use when extracting text from scanned PDFs, photographed pages, or images that have no embedded text layer. Covers OCR backends, language packs, force-OCR, and performance tuning.

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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.

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 `+`:

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:

# 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.

force_ocr = true
output_format = "markdown"

[ocr]
backend = "tesseract"
language = "eng+deu"
auto_rotate = true

Then just run:

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.