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Capturing Documents

OSS Document Scanner provides powerful capture capabilities with automatic edge detection, multiple capture modes, and batch scanning support.

Capture Screen

Capture Modes​

Auto Capture​

The default capture mode uses intelligent edge detection to automatically capture documents when:

  • The document is properly positioned within the viewfinder
  • All four edges are detected
  • The image is stable (no motion blur)

How to enable Auto Capture:

The first time you open the capture screen you'll be prompted to enable or disable Auto Capture. After that you can enable or disable it by long pressing the capture button

How to use Auto Capture:

  1. Hold your device steady above the document
  2. Wait for the green frame to appear around the document edges
  3. The app will automatically capture when conditions are optimal

Manual Capture​

For situations where auto-capture doesn't work well (glossy surfaces, low contrast) you can simply use the capture button

Batch Scanning​

Batch scanning allows you to scan multiple pages into a single document:

  1. Enable batch scanning with the button left of the capture button
  2. Start capturing pages as normal
  3. Each captured page is added to the current batch
  4. Review all pages in the batch preview
  5. Tap Done when finished to create the document

Auto Edge Detection​

The app uses advanced computer vision (OpenCV) to detect document edges:

How It Works​

  1. The camera feed is analyzed in real-time
  2. Contours are detected in the image
  3. Quadrilateral shapes are identified as potential documents
  4. The largest valid quadrilateral is selected as the document boundary

Tips for Better Detection​

  • Good lighting: Ensure even lighting without harsh shadows
  • Contrast: Place documents on contrasting backgrounds
  • Flat surface: Keep documents flat to avoid warped edges
  • Clean lens: Wipe your camera lens for clear captures

Manual Adjustment​

If auto-detection doesn't perfectly identify edges:

  1. After capture, the edge adjustment screen appears
  2. Drag the corner handles to adjust the document boundaries
  3. Drag edge midpoints for fine adjustments
  4. Tap Done to apply the selection

Edge Adjustment

Camera Settings​

Access camera settings by tapping the gear icon in the capture view:

Resolution (android)​

On android you can select the camera resolution based on your needs.

Flash Control​

  • Auto: Flash fires when needed in low light
  • On: Flash always fires
  • Off: Flash disabled

Torch mode​

You can use this to enable torch mode instead of Flash Control

Focus Mode​

  • Auto Focus: Tap to focus on specific areas
  • Continuous: Camera continuously adjusts focus

Transformations​

There you can select default brightness, contrast, fitlers... to apply to scanned documents

Document edges not detected​

  • Ensure good lighting conditions
  • Use a contrasting background
  • Try manual capture mode
  • Clean your camera lens

Blurry captures​

  • Hold the device steady
  • Wait for auto-focus to complete
  • Ensure adequate lighting
  • Try manual focus by tapping the screen

Auto-capture too sensitive/slow​

  • Adjust auto-capture sensitivity in settings
  • Switch to manual capture for difficult documents