PDF Translator

PDF Translation Skill

Translate PDF documents between any language pair with optimized support for academic papers and documents with complex layouts.

When to Use This Skill

Use this skill when:

• User wants to translate a PDF document to another language
• User has academic papers, research documents, or technical manuals to translate
• User needs to preserve document structure (tables, headings, lists) during translation
• User wants both Markdown and PDF output formats
• User mentions translating documents with tables, figures, or complex layouts

Usage

/pdf-translator <pdf_path> [options]

Arguments

• <pdf_path>: PDF file or directory containing PDFs

Options

Language Codes

ja (Japanese), en (English), ko (Korean), zh (Chinese), es (Spanish), fr (French), de (German), ru (Russian), ar (Arabic), he (Hebrew), or any ISO 639-1 code.

Examples

# Basic translation (English PDF to Korean)
/pdf-translator "/docs/manual.pdf"

# Japanese academic paper to Korean with terminology annotations
/pdf-translator "/papers/research.pdf" --source-lang ja --academic

# High-quality translation using Opus model
/pdf-translator "/papers/important.pdf" --high-quality

# Academic mode with footnote-style term annotations
/pdf-translator "/papers/thesis.pdf" --academic --term-style footnote

# Batch translation of a directory
/pdf-translator "/docs/" --target-lang ko --parallel 10

# Markdown output only
/pdf-translator "/books/novel.pdf" --output-format markdown

# Arabic RTL document to English
/pdf-translator "/docs/arabic.pdf" --source-lang ar --target-lang en

Architecture

flowchart LR
    PDF[PDF] --> Extract[extract_to_markdown.py]
    Extract --> Source[source.md + images/]
    Source --> Split[split_markdown.py]
    Split --> Sections[sections/]
    Sections --> Translate[Translator Agents]
    Translate --> Merged[translated.md]
    Merged --> GenPDF[generate_pdf.py]
    GenPDF --> Output[translated.pdf]

Key Features:

• Full document context preserved during translation
• Clean Markdown intermediate format (human-readable, editable)
• Section-based parallel translation for large documents
• pandoc + weasyprint for high-quality PDF output

Execution Workflow

Phase 0: Environment Setup

bash scripts/setup_env.sh

This installs pandoc and creates .venv/ with Python dependencies (pymupdf, pdfplumber, weasyprint).

PYTHON=".venv/bin/python"

Phase 1: Extract PDF to Markdown

WORK_DIR="/tmp/pdf_translate_$(date +%s)"
$PYTHON scripts/extract_to_markdown.py \
  --pdf "{PDF_PATH}" \
  --output-dir "$WORK_DIR" \
  --source-lang en \
  --target-lang ko

Output:

• $WORK_DIR/source.md - Original Markdown (preserves structure)
• $WORK_DIR/images/ - Extracted images
• $WORK_DIR/metadata.json - Document metadata

Phase 2: Split Markdown (if needed)

For large documents (>6000 tokens), split into sections:

$PYTHON scripts/split_markdown.py \
  --input "$WORK_DIR/source.md" \
  --output-dir "$WORK_DIR/sections" \
  --max-tokens 6000

Output:

• $WORK_DIR/sections/section_001.md
• $WORK_DIR/sections/section_002.md
• $WORK_DIR/sections/sections_manifest.json

Phase 3: Translation

Translate each section using the Markdown translator guide (references/translator_markdown.md).

Option A: Direct Translation (Small documents)

The orchestrator translates the Markdown directly:

1. Read source.md (or each section)
2. Translate following translator_markdown.md guidelines
3. Write to translated.md

Option B: Parallel Translation (Large documents)

Spawn Task agents for each section:

Task(
  subagent_type: "general-purpose",
  model: "sonnet",  // or "opus" for --high-quality
  run_in_background: false,
  prompt: "Read references/translator_markdown.md for guidelines.
           Translate $WORK_DIR/sections/section_001.md from English to Korean.
           Write output to $WORK_DIR/translated/section_001.md"
)

Phase 4: Merge Translated Sections

If split, merge translated sections:

cat $WORK_DIR/translated/section_*.md > $WORK_DIR/translated.md

Phase 5: Generate PDF

$PYTHON scripts/generate_pdf.py \
  --markdown "$WORK_DIR/translated.md" \
  --output "$OUTPUT_DIR/{filename}_translated.pdf"

Phase 6: Validation (Optional)

Review output for:

• Markdown formatting preserved
• Tables rendered correctly
• Images referenced properly
• No untranslated text

Model Selection

Default (no flags)

With --high-quality

Academic Mode (--academic)

When enabled:

• Technical terms include original language in parentheses
• Abbreviations expanded on first occurrence
• Citations and references preserved
• Formal academic writing style maintained

Term Annotation Styles (--term-style)

First Occurrence (--first-occurrence)

When true (default):

• First mention: 기계 학습(Machine Learning)
• Subsequent: 기계 학습

When false:

• All mentions include original term

Language-Specific Processing

Custom Dictionary (Optional)

The translator works without external dictionary files. It naturally translates based on context.

Use custom dictionaries ONLY for:

• Proper nouns: names, places, organizations, brands
• Document-specific terms: proprietary terms unique to this document

Do NOT add common words - let the translator handle them naturally.

Creating a Custom Dictionary

Use the --dict option with a JSON file:

{
  "metadata": {
    "source_language": "en",
    "target_language": "ko",
    "document_title": "Annual Report 2024"
  },
  "proper_nouns": {
    "names": { "John Smith": "존 스미스" },
    "places": { "Silicon Valley": "실리콘밸리" },
    "organizations": { "OpenAI": "OpenAI" }
  },
  "domain_terms": {
    "ProprietaryTech": "고유 기술명"
  },
  "preserve_original": {
    "terms": ["API", "GPU", "URL"]
  },
  "abbreviations": {
    "LLM": "Large Language Model"
  },
  "style_notes": {
    "notes": ""
  }
}

Templates

Work Directory Structure

$WORK_DIR/
├── source.md               # Original Markdown (extracted from PDF)
├── metadata.json           # Document metadata (title, pages, languages)
├── images/                 # Extracted images
│   ├── page001_img000.png
│   ├── page002_img000.png
│   └── ...
├── sections/               # Split sections (for large documents)
│   ├── section_001.md
│   ├── section_002.md
│   └── sections_manifest.json
├── translated/             # Translated sections
│   ├── section_001.md
│   ├── section_002.md
│   └── ...
└── translated.md           # Final merged translation

Error Handling

Text Processing

The following automatic text cleanup is applied during extraction and output generation:

PDF Extraction Error Correction

Some complex PDF artifacts cannot be fully corrected during extraction. The translator prompts include instructions to recognize and correct remaining errors:

• Split medical/scientific terms: broncho alveolar → bronchoalveolar
• Single-letter fragments: Diaphragm a tic → Diaphragmatic

See references/translator_markdown.md and references/translator_academic.md for details.

Header/Footer Detection

Automatically detects and removes common header/footer patterns:

• DOI links (https://doi.org/...)
• Journal volume/issue patterns (Journal| (2024) 16:642)
• Page numbers (standalone numbers at page boundaries)
• Date stamps (Received: 23 July 2024)
• Copyright notices

Superscript Handling

Reference numbers and author affiliations are detected by font size and converted to standard format:

• word¹ → word^[1]
• Author¹,² → Author^[1,2]

Reference Section Processing

Multi-language support for reference section headers:

• English: References, Bibliography, Works Cited
• Korean: 참고문헌
• German: Literatur, Literaturverzeichnis
• French: Références, Bibliographie
• Chinese/Japanese: 参考文献

List Detection

Automatically detects and formats various list styles:

• Bullet: •, ·, -, *, ▪, ▸, ►
• Numbered: 1., 1), (1), ①
• Roman: i., ii., iii.
• Letter: a., a), (a)

Output Formats

Markdown Output

• Preserves document structure (headings, paragraphs, lists)
• Tables converted to Markdown tables
• URLs converted to clickable links
• Metadata in YAML frontmatter

PDF Output

• Generated via pandoc + weasyprint from Markdown
• Clean text rendering with system fonts (Pretendard preferred)
• Proper table rendering with borders and headers
• Clickable links with styling
• Page numbers at bottom

File Reference

Known Limitations

PDF extraction has inherent limitations due to the format's nature:

Quality Expectations

• Academic papers: 85-95% accuracy on text extraction
• Technical manuals: 80-90% accuracy
• Complex layouts: 70-85% accuracy (flowcharts, multi-column)
• Tables: Variable (depends on structure complexity)

For best results with complex documents, review the extracted source.md before translation and manually correct any extraction errors.