Previously, I wrote an article demonstrating how to implement desktop passport MRZ recognition application using C++. Recently, Dynamsoft compiled the C++ OCR SDK to a web assembly module. It aims to help web developers to build web passport MRZ scanner applications using HTML5 and JavaScript. This article shows how to build web applications to read MRZ information from passport images and scan passport MRZ information with a camera in real time.

SDK Installation

The JavaScript OCR SDK has been published to npmjs.com.

To use the SDK, include https://cdn.jsdelivr.net/npm/dynamsoft-label-recognizer@2.2.0/dist/dlr.js in your HTML file.

<script 
src="https://cdn.jsdelivr.net/npm/dynamsoft-label-recognizer@2.2.0/dist/dlr.js"
></script>

For offline deployment, you can download the SDK via npm command in your terminal:

npm i dynamsoft-label-recognizer

SDK Activation

To make the SDK work, you need to:

1. Apply for a 30-day FREE Trial License.

2. Set the license key in JavaScript code:

Dynamsoft.DLR.LabelRecognizer.initLicense("LICENSE-KEY");

API Reference

• https://www.dynamsoft.com/camera-enhancer/docs/programming/javascript/api-reference/?ver=latest
• https://www.dynamsoft.com/label-recognition/programming/javascript/api-reference/?ver=latest

Web Passport MRZ Reader

Let’s get started with static passport images.

Here are the steps to create a web passport MRZ reader:

1. Initialize Dynamsoft Label Recognizer:

var
 recognizer = 
null
;
 Dynamsoft.DLR.LabelRecognizer.createInstance({
         runtimeSettings: "passportMRZ"
     }).then(
function
 (obj) {
         console.log("recognizer created");
         recognizer = obj;
     });

For the first time you create the instance of the SDK, it may take a long time to load the MRZ.data file, which is a model file used to recognize passport MRZ.

There are several scenario-specific OCR templates optional. In addition to passportMRZ, you can also set number, numberLetter, letter, or vin.

2. Create a button to load passport images:

<input
 type="file" id="file" accept="image/*" 
/>

3. Trigger the button change event to recognize MRZ from passport images:

document.getElementById("file").addEventListener("change", 
function
 () {
         
let
 file = 
this
.files[0];
         
if
 (recognizer) {
             recognizer.recognize(file).then(
function
 (results) {
                 
for
 (
let
 result 
of
 results) {
                     
if
 (result.lineResults.length == 2) {
                         
let
 lines = result.lineResults;
                         
let
 line1 = lines[0].text;
                         
let
 line2 = lines[1].text;
                         document.getElementById('result').innerHTML = extractMRZInfo(line1, line2);
                     }
                 }
             });
         }
     });

4. Finally, extract the MRZ information from a parser:

function
 extractMRZInfo(line1, line2) {
     
// https://en.wikipedia.org/wiki/Machine-readable_passport
     
let
 result = "";
     
// Type
     
let
 tmp = "Type: ";
     tmp += line1[0];
     result += tmp + "/\n/g";
    
     
// Issuing country
     tmp = "Issuing country: ";
     tmp += line1.substring(2, 5);
     result += tmp + "/\n/g";
    
     
// Surname
     
let
 index = 5;
     tmp = "Surname: ";
     
for
 (; index < 44; index++) {
         
if
 (line1[index] != '<') {
             tmp += line1[index];
         } 
else
 {
             
break
;
         }
     }
     result += tmp + "/\n/g";
    
     
// Given names
     tmp = "Given Names: ";
     index += 2;
     
for
 (; index < 44; index++) {
         
if
 (line1[index] != '<') {
             tmp += line1[index];
         } 
else
 {
             tmp += ' ';
         }
     }
     result += tmp + "/\n/g";
    
     
// Passport number
     tmp = "Passport number: ";
     index = 0;
     
for
 (; index < 9; index++) {
         
if
 (line2[index] != '<') {
             tmp += line2[index];
         } 
else
 {
             
break
;
         }
     }
     result += tmp + "/\n/g";
    
     
// Nationality
     tmp = "Nationality: ";
     tmp += line2.substring(10, 13);
     result += tmp + "/\n/g";
    
     
// Date of birth
     tmp = line2.substring(13, 19);
     tmp = tmp.substring(0, 2) +
         '/' +
         tmp.substring(2, 4) +
         '/' +
         tmp.substring(4, 6);
     tmp = "Date of birth (YYMMDD): " + tmp;
     result += tmp + "/\n/g";
    
     
// Sex
     tmp = "Sex: ";
     tmp += line2[20];
     result += tmp + "/\n/g";
    
     
// Expiration date of passport
     tmp = line2.substring(21, 27);
     tmp = tmp.substring(0, 2) +
         '/' +
         tmp.substring(2, 4) +
         '/' +
         tmp.substring(4, 6);
     tmp = "Expiration date of passport (YYMMDD): " + tmp;
     result += tmp + "/\n/g";
    
     
// Personal number
     
if
 (line2[28] != '<') {
         tmp = "Personal number: ";
         
for
 (index = 28; index < 42; index++) {
             
if
 (line2[index] != '<') {
                 tmp += line2[index];
             } 
else
 {
                 
break
;
             }
         }
         result += tmp + "/\n/g";
     }
    
     
return
 result;
 }

We can find some MRZ images from Google to test the simple web MRZ reader:

The MRZ recognition results:

Web Passport MRZ Scanner

Now, we can combine Dynamsoft Camera Enhancer and Dynamsoft Label Recognizer to quickly turn the MRZ reader into a MRZ scanner.

We include the JavaScript camera SDK to the HTML file:

<script 
src="https://cdn.jsdelivr.net/npm/dynamsoft-label-recognizer@2.2.0/dist/dlr.js"
></script>
<script 
src="https://cdn.jsdelivr.net/npm/dynamsoft-camera-enhancer@2.1.0/dist/dce.js"
></script>

As the Dynamsoft Label Recognizer is initialized, we create the camera enhancer object:

<div
 id="enhancerUIContainer" style="height: 100vh;"
></div>
<script>
    Dynamsoft.DLR.LabelRecognizer.createInstance({
        runtimeSettings: "passportMRZ"
    }).then(
function
 (obj) {
        console.log("recognizer created");
        recognizer = obj;
    
        (
async
 () => {
            enhancer = 
await
 Dynamsoft.DCE.CameraEnhancer.createInstance();
            document.getElementById("enhancerUIContainer").appendChild(enhancer.getUIElement());
            
await
 enhancer.open(
true
);
            scanMRZ();
        })();
    });
</script>

Then continuously call the scanMRZ() function, in which we get the camera frame and call the MRZ recognition API:

function
 scanMRZ() {        
    
let
 frame = enhancer.getFrame();
    
if
 (recognizer) {
        recognizer.recognize(frame.canvas).then(
function
 (results) {
            div.innerHTML = '';
            
for
 (
let
 result 
of
 results) {
                
if
 (result.lineResults.length == 2) {
                    
let
 lines = result.lineResults;
                    
let
 line1 = lines[0].text;
                    
let
 line2 = lines[1].text;
                    console.log(line1);
                    console.log(line2);
                    div.innerHTML = extractMRZInfo(line1, line2);
                }
            }
            scanMRZ();
        });
    }
}

With a few lines of HTML5 and JavaScript code, a simple web MRZ scanner is done. We can now scan passport from desktop and mobile web browsers in real time.

Source Code

https://github.com/yushulx/javascript-passport-mrz-scanner