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samk_au's avatar
samk_au
Copper Contributor
Aug 30, 2026

Purview on-demand classification to scan historical image files?

I’m working on a project to identify PII across SharePoint and OneDrive. While we can use Purview On-Demand Classification for this purpose, it does not currently support image file types, so I’m looking for an alternative way to identify PII within historical image files.

My initial thought was to enable OCR and then run an On-Demand Classification scan. However, my understanding is that OCR generally applies to images added or modified after OCR is enabled, so I’m not sure whether an On-Demand Classification scan can trigger OCR processing for existing historical images.

Could you please clarify the following:

  • Can On-Demand Classification trigger OCR processing for existing image files in SharePoint and OneDrive?
  • If not, is there another supported method to trigger OCR processing for historical images that are already stored in these locations?
  • What would be the recommended approach for discovering and classifying PII within historical image files at scale?

Thanks!

1 Reply

  • Jamony's avatar
    Jamony
    MCT
    Sep 01, 2026

    You identified the gap: Purview OCR processes only images uploaded after OCR is enabled, while on-demand classification targets historical files. Microsoft does not state that an on-demand scan retroactively triggers OCR for old images. Therefore, do not assume enabling OCR and launching a scan will extract text from the existing estate. Enable OCR for SharePoint and OneDrive so new supported images are scanned, then run a small on-demand classification estimate against a test site containing known historical images and review whether those extensions are eligible. Purview supports many image formats and scanned PDFs, subject to size and resolution limits, but support does not override the upload-after-enable restriction. For existing images that remain unprocessed, Microsoft documents no bulk re-OCR switch. Open a Microsoft support case for tenant-specific confirmation before touching production content. If re-uploading is considered, test copies first because it changes versions, timestamps, audit history, and potentially retention behavior.