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Editing and Enhancing Documents

After capturing a document, OSS Document Scanner provides comprehensive editing tools to perfect your scans.

Edit Screen

Rename​

  1. Open the document
  2. click on the document name in the actionbar
  3. rename the document
  4. click the Save button

Cropping and Rotation​

Manual Cropping​

Fine-tune the document boundaries after capture:

  1. Open the edit view for a scanned page
  2. Select the Crop tool
  3. Drag corner handles to adjust the document area
  4. Drag edge midpoints for precise adjustments
  5. Use the grid overlay for alignment
  6. Tap Apply to save changes

Rotation​

Correct document orientation, tap the rotate button to rotate in 90° increments

Perspective Correction​

The app automatically applies perspective correction based on the detected document edges. This ensures:

  • Parallel edges appear parallel
  • Rectangular documents appear rectangular
  • Text lines are straightened

Image Filters​

Apply filters to enhance document readability:

Black & White​

Converts to pure black and white (binary):

  • Ideal for text documents
  • Smallest file size
  • Best for OCR processing
  • Adjustable threshold for optimal results

Grayscale​

Removes color while preserving tonal range:

  • Good for documents with diagrams
  • Smaller file size than color
  • Natural appearance

Color Enhanced​

Improves color documents:

  • Automatic white balance
  • Contrast enhancement
  • Color saturation adjustment

Original​

Keeps the image as captured:

  • Full color preservation
  • No processing applied
  • Largest file size

Document Enhancement​

Smart enhancement for documents:

  • Shadow removal
  • Uneven lighting correction
  • Edge sharpening
  • Background cleanup

Advanced Adjustments​

Brightness and Contrast​

Fine-tune image appearance:

  1. Tap Adjust in the edit toolbar
  2. Use sliders to adjust:
    • Brightness: Lighten or darken the image
    • Contrast: Increase or decrease tonal range
  3. Preview changes in real-time
  4. Tap Apply to save

OCR (Optical Character Recognition)​

Extract text from scanned documents:

Running OCR​

  1. Open a document page
  2. Tap the OCR button
  3. Select the language(s) of the text
  4. Wait for processing to complete
  5. View and copy extracted text

Detect and Copy (Android)​

For quick text extraction, use the app shortcut action.

OCR Features​

  • Multi-language support: OCR works with many languages
  • Copy text: Copy extracted text to clipboard
  • Search: Search within extracted text
  • Export: Include OCR text in PDF exports
  • Transparent OCR in PDF: Add searchable text layer to exported PDFs

OCR Tips​

  • Use Black & White filter for best results
  • Ensure good capture quality
  • Select correct language(s)
  • For handwriting, results may vary
  • Download language models from Settings > OCR before use
OCR Processing

OCR uses Tesseract for text recognition. Processing happens on-device for privacy. See app/services/ocr.ts for implementation details.

Page Management​

Reordering Pages​

In multi-page documents:

  1. Open the document view
    • Tap the Reorder Pages menu entry in the three dot action menu
    • or long-press and start dragging a page
  2. Drag to the new position
  3. Release to drop
  4. The document is automatically saved

Deleting Pages​

Remove unwanted pages:

  1. Open the document view
  2. Select pages to delete (tap thumbnails)
  3. Tap the Delete button
  4. Confirm deletion

Adding Pages​

Add more pages to existing documents:

  1. Open the document
  2. Tap Add Page or Camera buttons
  3. Capture new pages
  4. Pages are appended to the document

Best Practices​

For Text Documents​

  1. Use Black & White filter
  2. Ensure high contrast
  3. Run OCR for searchable PDFs
  4. Use perspective correction

For Photos/Diagrams​

  1. Use Grayscale or Color Enhanced
  2. Adjust brightness/contrast as needed
  3. Keep original resolution

For Receipts​

  1. Use Whitepaper
  2. Apply shadow removal
  3. Increase contrast slightly
  4. Consider Black & White for faded receipts