extracting-with-ocr

Extracting with OCR

Use this when a document is image-based: scanned PDFs, photographed pages,

screenshots, JPEG/PNG/TIFF with text. Kreuzberg 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.

kreuzberg extract scan.pdf --force-ocr=true
kreuzberg 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. |

| EasyOCR | --ocr-backend easyocr | Python binding (pip install kreuzberg[easyocr])| Heavier model. CUDA accel via easyocr_kwargs={"gpu": True}. |

| VLM (vision) | layout + a multimodal LLM via config | configured per backend | 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 +:

kreuzberg extract menu.jpg --ocr=true --ocr-language "eng+deu"
kreuzberg extract bilingual.pdf --ocr-language "eng+jpn"
kreuzberg 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>

Kreuzberg 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|easyocr> — 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 kreuzberg 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 kreuzberg.toml — auto-discovered from cwd

upward.

force_ocr = true
output_format = "markdown"

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

Then just run:

kreuzberg 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 kreuzberg skill for the full flag and config schema.