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Adjust PDF Colours and Contrast

This adjusts brightness, contrast and saturation across the pages. On old or faint scans it is often the difference between a page OCR cannot read and one it can.

How to Adjust PDF Colours and Contrast

  1. Upload the PDF.
  2. Adjust brightness, contrast and saturation.
  3. Apply, then download the improved file.

When you would use this

  • Darkening a faded carbon copy so it can be read.
  • Increasing contrast before running OCR.
  • Cleaning up a grey background from an old scan.

Questions

Will this improve OCR accuracy?

Often significantly. Clean contrast between text and background is what OCR depends on most.

Can I recover very faint text?

Sometimes. If the ink registered at all, raising contrast can bring it up. If nothing was captured, nothing can be recovered.

Does it affect real text?

Only scanned images are altered. Digitally drawn text is unaffected.

Need this at scale?

These tools handle one document at a time. When the job is thousands of files, Greenbooks handles document digitization as a managed service, including bulk scanning, OCR and metadata capture, with the output loaded into DocuVenta DMS. Talk to us about volume work.

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