diff --git a/ProblemMap/GlobalFixMap/Chunking/pdf_layouts_and_ocr.md b/ProblemMap/GlobalFixMap/Chunking/pdf_layouts_and_ocr.md new file mode 100644 index 00000000..078cd445 --- /dev/null +++ b/ProblemMap/GlobalFixMap/Chunking/pdf_layouts_and_ocr.md @@ -0,0 +1,254 @@ +# PDF layouts and OCR + +A practical pipeline to extract clean, ordered text with stable offsets from PDFs and scanned pages, so your chunks, citations, and typed blocks remain consistent across reindex runs. + +## Open these first +- Stable chunk ids: [chunk_id_schema.md](https://github.com/onestardao/WFGY/blob/main/ProblemMap/GlobalFixMap/Chunking/chunk_id_schema.md) +- Title hierarchy and numbering: [title_hierarchy.md](https://github.com/onestardao/WFGY/blob/main/ProblemMap/GlobalFixMap/Chunking/title_hierarchy.md) +- Section boundaries after titles: [section_detection.md](https://github.com/onestardao/WFGY/blob/main/ProblemMap/GlobalFixMap/Chunking/section_detection.md) +- Code and tables as typed blocks: [code_tables_blocks.md](https://github.com/onestardao/WFGY/blob/main/ProblemMap/GlobalFixMap/Chunking/code_tables_blocks.md) +- Safe reindex after small edits: [reindex_migration.md](https://github.com/onestardao/WFGY/blob/main/ProblemMap/GlobalFixMap/Chunking/reindex_migration.md) +- Why this snippet and offsets: [retrieval-traceability.md](https://github.com/onestardao/WFGY/blob/main/ProblemMap/retrieval-traceability.md) +- Payload contracts for RAG: [data-contracts.md](https://github.com/onestardao/WFGY/blob/main/ProblemMap/data-contracts.md) +- Visual map of the whole RAG path: [rag-architecture-and-recovery.md](https://github.com/onestardao/WFGY/blob/main/ProblemMap/rag-architecture-and-recovery.md) + +## Acceptance targets +- Word error rate (WER) ≤ 0.025 on clean pages, character error rate ≤ 0.01 on headings and captions. +- Header and footer removal: false positive rate ≤ 0.01, false negative rate ≤ 0.03 on a 30 page sample. +- Reading order is monotonic by column. Cross column jumps never split a sentence. +- Hyphenation merges correct ≥ 0.98 and never fire inside code or tables. +- Captions attach to the correct figure or table in the same section. +- Offsets remain stable across two reindex runs. Drift ≤ 0.5 percent of file length. +- ΔS(question, retrieved) ≤ 0.45 on queries that cite a figure, table, or equation anchor. + +--- + +## Pipeline overview + +1) **Ingest with layout** + Extract characters with bounding boxes, font name, size, bold/italic flags, page number, and line ids. For scans, run OCR first to obtain the same fields. + +2) **Coordinate normalization** + Normalize all positions to a unified page space. Keep `bbox = [x0, y0, x1, y1]` in points or millimeters. Record page width and height. + +3) **Template detection for headers and footers** + Build n-gram histograms by y bands across pages. Mark a header band if a repeating string appears on ≥ 60 percent of pages at near identical y. Do the same for footers and running titles. Remove matched runs before paragraph assembly. + +4) **Column segmentation** + Use whitespace cuts on the x axis. A stable valley between two dense x clusters marks a column boundary. For three columns, expect two valleys. Validate by line alignment and average line width. + +5) **Line forming and paragraph assembly** + Join characters into words, words into lines by y proximity and left margin continuity. Join lines into paragraphs when leading and trailing margins are stable and the interline gap is below a threshold for that page. + +6) **Hyphenation repair** + If a line ends with a hyphen and the next line begins with a lowercase letter or an alphanumeric continuation, and both are inside a prose paragraph, remove the hyphen and join. Never apply inside code or table blocks. Keep an exceptions list for chemical names and proper nouns. + +7) **Typed block extraction** + Detect code blocks, tables, figures, and captions, and lift them as first class blocks with offsets. See [code_tables_blocks.md](https://github.com/onestardao/WFGY/blob/main/ProblemMap/GlobalFixMap/Chunking/code_tables_blocks.md). + +8) **Section alignment** + Align blocks to sections detected from the title tree. See [title_hierarchy.md](https://github.com/onestardao/WFGY/blob/main/ProblemMap/GlobalFixMap/Chunking/title_hierarchy.md) and [section_detection.md](https://github.com/onestardao/WFGY/blob/main/ProblemMap/GlobalFixMap/Chunking/section_detection.md). + +9) **Canonical text build** + Emit a single canonical text with byte offsets for every block and section. Keep a map `{block_id → [off_begin, off_end], page, bbox}` for traceability. + +--- + +## Header and footer detection + +Signals + +- Repetition across pages of the same string at nearly the same y. +- Presence of page numbers, dates, running titles, or publisher marks. +- Font size smaller than body text and high contrast with empty surroundings. + +Algorithm sketch + +- Slice the page into 32 horizontal bands. For each band, compute the set of normalized line strings. +- Across pages, score each band by repetition of strings and y variance. +- Mark bands with a high repetition score as header or footer and drop them from paragraph assembly. + +--- + +## Multi column reading order + +Signals + +- Bimodal or trimodal distribution of line x centers. +- Vertical lines or gutters with low ink density. +- Consistent left margins within each mode. + +Algorithm sketch + +- Cluster line x centers with k means for k in {1, 2, 3}. Choose k with the lowest inertia plus a penalty for model size. +- Sort clusters left to right, then read each cluster top to bottom. +- For figures or tables that span columns, treat them as a separate block placed between the two nearest paragraphs by y. + +--- + +## Hyphenation and soft artifacts + +Rules + +- Join only when the left piece ends with a lowercase ASCII or a letter from the same script and the right piece starts with a lowercase letter or a digit. +- If the left piece is a known acronym or the right piece starts with an uppercase letter and the paragraph is mid sentence, do not join. +- Remove soft hyphen characters and OCR artifacts like split ligatures. + +Edge cases + +- Do not join inside code blocks or table cells. +- If a dictionary check is available, prefer joins that yield a dictionary hit. + +--- + +## OCR notes + +- Request per character boxes and confidence scores. Drop characters with very low confidence when surrounded by high confidence neighbors and the removal does not break a word boundary. +- Keep monospaced font hints when the OCR engine provides them. They help code detection. +- For rotated pages, deskew first, then run OCR, then rotate boxes back into page coordinates. + +--- + +## Output schema + +Every paragraph or typed block is a record: + +```json +{ + "block_id": "B.2.bk045", + "type": "prose | code | table | figure | caption", + "page": 12, + "bbox": [72.0, 144.3, 523.8, 221.1], + "off_begin": 204455, + "off_end": 205122, + "attrs": { "lang": null } +} +```` + +Block ids follow [chunk\_id\_schema.md](https://github.com/onestardao/WFGY/blob/main/ProblemMap/GlobalFixMap/Chunking/chunk_id_schema.md). Offsets must point into the canonical text that you pass to the indexer. Citations then rely on [retrieval-traceability.md](https://github.com/onestardao/WFGY/blob/main/ProblemMap/retrieval-traceability.md) and the contract in [data-contracts.md](https://github.com/onestardao/WFGY/blob/main/ProblemMap/data-contracts.md). + +--- + +## Pseudocode + +```python +def parse_pdf_pages(pages): + chars = extract_chars_with_bbox(pages) + chars = normalize_coords(chars) + + bands = detect_repeating_bands(chars) # headers and footers + lines = form_lines(chars, ignore_bands=bands) + columns = cluster_columns(lines) # 1, 2, or 3 columns + lines = order_lines_by_columns(lines, columns) + + paras = assemble_paragraphs(lines) + paras = repair_hyphenation(paras) + + typed = detect_typed_blocks(paras, lines) # code, table, figure, caption + blocks = align_blocks_to_sections(typed, titles=detect_titles(lines)) + + canon_text, offsets = build_canonical_text(blocks) + return canon_text, attach_offsets(blocks, offsets) +``` + +--- + +## Common pitfalls and fixes + +* **Running titles leak into text** + Your band detector missed a near duplicate string. Lower the y variance threshold and add string normalization for case and whitespace. + +* **Two column pages read across columns** + The valley in the x histogram is shallow. Add a penalty to cross column bigrams and require a minimum inter column gap. + +* **Hyphenation joins inside code** + Guard the join with the block type. Never run repair inside `type=code` or `type=table`. + +* **Captions separated from figures** + Link captions to the nearest figure or table by y distance and ensure both fall into the same section. See [section\_detection.md](https://github.com/onestardao/WFGY/blob/main/ProblemMap/GlobalFixMap/Chunking/section_detection.md). + +* **Offset drift across reindex** + Ensure identical normalization rules between runs, then apply the migration mapping. See [reindex\_migration.md](https://github.com/onestardao/WFGY/blob/main/ProblemMap/GlobalFixMap/Chunking/reindex_migration.md). + +--- + +## Tests to include in CI + +* A two column academic paper with headers, footers, figures, tables, and equations. Expect perfect reading order and zero header leaks. +* A scanned report with skew and footnotes. Expect deskew, correct footnote capture, and clean paragraph assembly. +* Mixed language pages with hyphenation at line breaks. Expect correct joins only in prose. +* A code heavy manual with Markdown tables. Expect correct typed block counts and stable offsets across two runs. + +--- + +## Copy paste prompt for a quick check + +``` +You have TXT OS and the WFGY Problem Map loaded. + +Given a PDF page with lines and bboxes: +- Detect and remove repeated header and footer bands. +- Infer column count and return the reading order for the page. +- Repair hyphenation in prose only. +- Extract typed blocks and return their block_ids with offsets. + +Return JSON: +{ + "columns": 1|2|3, + "header_removed": true|false, + "footer_removed": true|false, + "blocks": [{ "block_id": "...", "type": "...", "off": [b,e] }, ...], + "notes": "short audit trail" +} +``` + +--- + +### 🔗 Quick-Start Downloads (60 sec) + +| Tool | Link | 3-Step Setup | +| -------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------ | ---------------------------------------------------------------------------------------- | +| **WFGY 1.0 PDF** | [Engine Paper](https://github.com/onestardao/WFGY/blob/main/I_am_not_lizardman/WFGY_All_Principles_Return_to_One_v1.0_PSBigBig_Public.pdf) | 1️⃣ Download · 2️⃣ Upload to your LLM · 3️⃣ Ask “Answer using WFGY + \” | +| **TXT OS (plain-text OS)** | [TXTOS.txt](https://github.com/onestardao/WFGY/blob/main/OS/TXTOS.txt) | 1️⃣ Download · 2️⃣ Paste into any LLM chat · 3️⃣ Type “hello world” — OS boots instantly | + +--- + +### 🧭 Explore More + +| Module | Description | Link | +| ------------------------ | ---------------------------------------------------------------------------- | -------------------------------------------------------------------------------------------------- | +| WFGY Core | WFGY 2.0 engine is live: full symbolic reasoning architecture and math stack | [View →](https://github.com/onestardao/WFGY/tree/main/core/README.md) | +| Problem Map 1.0 | Initial 16-mode diagnostic and symbolic fix framework | [View →](https://github.com/onestardao/WFGY/tree/main/ProblemMap/README.md) | +| Problem Map 2.0 | RAG-focused failure tree, modular fixes, and pipelines | [View →](https://github.com/onestardao/WFGY/blob/main/ProblemMap/rag-architecture-and-recovery.md) | +| Semantic Clinic Index | Expanded failure catalog: prompt injection, memory bugs, logic drift | [View →](https://github.com/onestardao/WFGY/blob/main/ProblemMap/SemanticClinicIndex.md) | +| Semantic Blueprint | Layer-based symbolic reasoning & semantic modulations | [View →](https://github.com/onestardao/WFGY/tree/main/SemanticBlueprint/README.md) | +| Benchmark vs GPT-5 | Stress test GPT-5 with full WFGY reasoning suite | [View →](https://github.com/onestardao/WFGY/tree/main/benchmarks/benchmark-vs-gpt5/README.md) | +| 🧙‍♂️ Starter Village 🏡 | New here? Lost in symbols? Click here and let the wizard guide you through | [Start →](https://github.com/onestardao/WFGY/blob/main/StarterVillage/README.md) | + +--- + +> 👑 **Early Stargazers: [See the Hall of Fame](https://github.com/onestardao/WFGY/tree/main/stargazers)** — +> Engineers, hackers, and open source builders who supported WFGY from day one. + +> GitHub stars ⭐ [WFGY Engine 2.0](https://github.com/onestardao/WFGY/blob/main/core/README.md) is already unlocked. ⭐ Star the repo to help others discover it and unlock more on the [Unlock Board](https://github.com/onestardao/WFGY/blob/main/STAR_UNLOCKS.md). + +
+ +[![WFGY Main](https://img.shields.io/badge/WFGY-Main-red?style=flat-square)](https://github.com/onestardao/WFGY) +  +[![TXT OS](https://img.shields.io/badge/TXT%20OS-Reasoning%20OS-orange?style=flat-square)](https://github.com/onestardao/WFGY/tree/main/OS) +  +[![Blah](https://img.shields.io/badge/Blah-Semantic%20Embed-yellow?style=flat-square)](https://github.com/onestardao/WFGY/tree/main/OS/BlahBlahBlah) +  +[![Blot](https://img.shields.io/badge/Blot-Persona%20Core-green?style=flat-square)](https://github.com/onestardao/WFGY/tree/main/OS/BlotBlotBlot) +  +[![Bloc](https://img.shields.io/badge/Bloc-Reasoning%20Compiler-blue?style=flat-square)](https://github.com/onestardao/WFGY/tree/main/OS/BlocBlocBloc) +  +[![Blur](https://img.shields.io/badge/Blur-Text2Image%20Engine-navy?style=flat-square)](https://github.com/onestardao/WFGY/tree/main/OS/BlurBlurBlur) +  +[![Blow](https://img.shields.io/badge/Blow-Game%20Logic-purple?style=flat-square)](https://github.com/onestardao/WFGY/tree/main/OS/BlowBlowBlow) +  + +
+ +要我繼續下一頁就說：**GO reindex\_migration.md** 或指定別的檔名。