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Use measured workload categories and complete output requirements; the fastest clean page is not a reliable estimate for an archive.
Size a GPU OCR server for a thousand PDF pages using a representative document sample, the complete pipeline and reprocessing rate. Multiplying the fastest clean page by a thousand misses difficult layouts, image preparation and queueing. The number 1,000 defines a planned workload here, not a published hardware result.
Classify the PDF inputs
Identify pages with useful text layers, scanned images, tables and complex layouts. Record the selected engine, device and enabled components. Basic text recognition and structural document processing do different work, so their timings should not be mixed without explanation.
Confirm the required output: plain text, structured fields or a searchable PDF. These deliverables have different preparation and assembly steps. Preserve the source-page relationship so missing output can be traced to its original page rather than hidden in an aggregated document.
Sample difficult classes deliberately
| Page class | Sample content | Main quality check |
|---|---|---|
| Clean text | Typical resolution | Character errors |
| Tables | Ordinary and dense cells | Cell ordering |
| Rotation or skew | Realistic deviations | Preparation quality |
| Poor scan | Noise and weak contrast | Missing or incorrect fields |
| Complex layout | Columns and captions | Reading order |
Keep the distribution representative rather than selecting only convenient pages. Save labeled examples and include failures in the report. A skipped page is different from a completed page with recognition errors, and both affect the usable result.
Time the complete pass
Include rendering, preprocessing, recognition, structure handling, output writing and assembly. Measure CPU, RAM, storage and GPU alongside the timeline. A GPU-only interval does not describe how long a user waits for the completed PDF.
For illustration, suppose 800 ordinary pages take two seconds each and 200 complex pages take six seconds each in a sequential measurement. That arithmetic gives 2,800 seconds before shared overhead and retries. These are invented teaching inputs for the formula, not observed performance of any OCR engine or card.
Verify the estimate and preserve results
Replace the illustrative values with measurements from your sample, then add observed preparation and retry overhead. Explain assumptions about concurrency instead of assuming linear scaling. Review the complete output for missing pages, incorrect ordering and usable text layers where required.
Save page IDs, configuration, quality findings and durable result locations. This lets an equipment owner show a concrete OCR role and an operations partner assess an actual stage budget.
Official references: paddleocr.ai — OCR, tesseract-ocr.github.io — FAQ.
Related guides: Tesseract and GPU acceleration: why installing CUDA is insufficient, ComfyUI GPU requirements depend on the entire workflow.