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Anyone having issues with OCR accuracy on scanned PDFs with columns?

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(@elenar)
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Joined: 1 week ago
Posts: 78
Topic starter   [#9323]

I have been conducting an extensive evaluation of Speechify's text-to-speech capabilities for academic research workflows, specifically focusing on the ingestion and conversion of scanned journal articles and legacy reports. My primary use case involves automating the initial auditory review of lengthy documents to triage relevance before deep analysis. While the core TTS engine performs admirably with clean digital text, I have encountered significant and systemic issues with the Optical Character Recognition accuracy when processing scanned PDFs that utilize a multi-column layout.

The problem manifests in several predictable failure modes:

* **Column Boundary Cross-Talk:** The OCR engine frequently fails to correctly isolate columns. It will read horizontally across the page, stitching together fragments from adjacent columns, which renders the output nonsensical. For example, it might combine the last few words from a paragraph in the left column with the first words of a caption in the right column, completely destroying semantic continuity.
* **Header and Footer Inclusion:** Running headers, page numbers, and footnotes are indiscriminately interleaved with the main body text. In a data analysis context, this introduces severe noise, as the software will vocalize "Journal of Statistical Methods, Vol. 12, Page 45" repeatedly throughout the reading.
* **Ordering of Complex Layouts:** Documents with mixed layouts—such as a single-column abstract followed by a two-column main body—often have their reading order scrambled. The software does not appear to employ a robust page segmentation algorithm to detect these logical regions.

I have attempted to mitigate this by experimenting with Speechify's built-in processing settings, but the controls are notably coarse-grained for this class of problem. There is no option to specify layout hints or to apply pre-processing for column detection. My current workaround involves using a separate, specialized OCR tool (Tesseract with custom page segmentation modes) to extract the text first, save it as a plain text file, and then feed that result into Speechify. This naturally adds complexity and breaks the intended seamless workflow.

My questions for the community are thus analytical:

* Has anyone performed a structured accuracy test comparing Speechify's native OCR against other dedicated engines (Adobe, ABBYY, or open-source solutions) for multi-column source material? Quantitative error rates (e.g., Character Error Rate, Word Error Rate) would be invaluable.
* Are there specific scanning resolutions or PDF preprocessing steps (e.g., applying a slight margin crop, converting to a high-resolution image format first) that have empirically improved Speechify's layout analysis?
* From a cost-per-query and performance tuning perspective, does it appear more efficient to accept the workflow overhead of external OCR, or is there a configuration paradigm within Speechify I have overlooked that makes the integrated solution viable for production-scale processing of such documents?

The trade-off here is clear: convenience versus accuracy. For casual use, the errors might be tolerable, but for analytical or research purposes where the integrity of the information is paramount, these inaccuracies present a significant bottleneck. I am interested in a dissection of where the tool's limitations lie and whether the development roadmap suggests improvements in document layout understanding.


Data doesn't lie, but folks sometimes do.


   
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