opencvjs-document-scanner

A document scanner implemented with opencv.js. It can detect the boundaries of documents and apply perspective transformation to get a deskewed image.

Online demo

opencv-document-scanner.mp4

Example:

Installation

Via NPM:

npm install opencv-document-scanner

Via CDN:

<script type="module">
  import { DocumentScanner } from 'https://cdn.jsdelivr.net/npm/opencv-document-scanner/dist/opencv-document-scanner.js';
</script>

You also need to include OpenCV:

<script type="text/javascript">
  var Module = {
    // https://emscripten.org/docs/api_reference/module.html#Module.onRuntimeInitialized
    onRuntimeInitialized() {
      document.getElementById('status').innerHTML = 'OpenCV.js is ready.';
    }
  };
</script>
<script async src="https://docs.opencv.org/4.8.0/opencv.js" type="text/javascript"></script>

Usage

1. Initialize an instance.

   const documentScanner = new DocumentScanner();

2. Detect the polygon of documents and return the points.

   const imgElement = document.getElementById("photoRaw")
   const points = documentScanner.detect(imgElement); //detect from an img or canvas element

3. Get the cropped document image.

   let imgElement = document.getElementById("photoRaw")
   const canvas = documentScanner.crop(imgElement); //get cropped image from an img or canvas element

4. Live scanning with camera using Dynamsoft Document Viewer.

   <script type="module">
     import { DocumentScanner } from 'https://cdn.jsdelivr.net/npm/opencv-document-scanner/dist/opencv-document-scanner.js';
     const documentScanner = new DocumentScanner();
     const detectHandler = new OpenCVDocumentDetectHandler(documentScanner);
     Dynamsoft.DDV.setProcessingHandler("documentBoundariesDetect", detectHandler);
   </script>

   

5. Edit the polygon with Dynamsoft Document Viewer.

   const points = documentScanner.detect(imgElement);
   const quad = [];
   points.forEach(point => {
     quad.push([point.x,point.y]);
   });
   perspectiveViewer.setQuadSelection(quad);

   

Blog

Web Document Scanner with OpenCV.js