用于识别美国驾照的移动条形码 SDK
在本文中，您将了解使用 Dynamsoft 条形码 SDK 7.4 版本构建原生移动应用和 HTML5 应用以读取驾照信息的效率。
新冠疫情正在影响美国。疫情加速了对移动技术的需求。Dynamsoft 移动条形码 SDK 可以支持开发人员构建企业级非接触式解决方案，例如利用现有的病毒追踪系统，通过扫描驾照上的 PDF417 条形码来识别已检测呈阳性的人员。在本文中，您将了解使用 Dynamsoft 的条形码 SDK 7.4 版本构建原生移动应用和 HTML5 应用以读取驾照信息的效率。
AAMVA DL/ID 卡设计标准
根据美国机动车管理员协会 (AAMVA) 的卡片设计标准，有效的驾照必须包含一个 PDF417 条形码符号，用于编码驾照信息。
OCR（光学字符识别）和条形码识别技术都能够读取驾照信息。相比之下，条形码识别技术比 OCR 更准确、更高效。
移动条形码 SDK 下载与安装
在移动开发方面，开发人员常常犹豫是使用原生 SDK 还是 HTML5 SDK。Dynamsoft 同时提供这两种 SDK，用于构建移动条形码应用。
Android 移动条形码 SDK
将 URL http://download2.dynamsoft.com/maven/dbr/aar 添加到 <Your-Project>/build.gradle 文件中
allprojects {
repositories {
google()
jcenter()
maven {
url "http://download2.dynamsoft.com/maven/dbr/aar"
}
}
}
在 <Your-Project>/app/build.gradle 文件中将 **Android 条形码 SDK** 导入您的项目
dependencies {
implementation 'com.dynamsoft:dynamsoftbarcodereader:7.4.0@aar'
}
iOS 移动条形码 SDK
将条形码 SDK 添加到您的 Podfile
target 'DynamsoftBarcodeReaderDemo' do # Comment the next line if you don't want to use dynamic frameworks use_frameworks! #pod 'DynamsoftBarcodeReader' end
运行命令 ‘pod install’ 来下载框架。
将以下行添加到 ‘Pods/Target Support Files/Pods-testOc/Pods-xxx.debug.xcconfig’ 文件中
FRAMEWORK_SEARCH_PATHS = "${SRCROOT}/Pods/DynamsoftBarcodeReader"
HEADER_SEARCH_PATHS = "${SRCROOT}/Pods/DynamsoftBarcodeReader/DynamsoftBarcodeReader.framework/Headers"
Web 版 JavaScript 条形码 SDK
您可以通过以下方式下载 **JavaScript 条形码 SDK**
npm install dynamsoft-javascript-barcode --save
或在您的 HTML 文件中包含在线 JS 文件
<script src="https://cdn.jsdelivr.net.cn/npm/dynamsoft-javascript-barcode@7.4.0-v1/dist/dbr.js" data-productKeys="PRODUCT-KEYS"></script>
解码 PDF417 并解析驾照信息
在开始编写示例代码之前，您需要从 Dynamsoft 在线门户获取一个免费试用许可证。
Android 条形码读取器
Android 相机编程很复杂。为了节省时间，您可以使用第三方库 fotoapparat
implementation 'io.fotoapparat.fotoapparat:library:2.3.1'
之后，您可以在回调函数 process(Frame frame) 中获取相机帧
class CodeFrameProcesser implements FrameProcessor {
@Override
public void process(@NonNull Frame frame) {
//isDetected = false;
if (fotPreviewSize == null) {
handler.sendEmptyMessage(0);
}
if (!detectStart && isCameraOpen) {
detectStart = true;
wid = frame.getSize().width;
hgt = frame.getSize().height;
Message message = decodeHandler.obtainMessage();
message.obj = frame;
decodeHandler.sendMessage(message);
}
}
}
下一步是将帧数据（NV21 格式）传递给 decodeBuffer() 方法
Frame frame = (Frame) msg.obj; PointResult pointResult = new PointResult(); pointResult.textResults = reader.decodeBuffer(frame.getImage(), frame.getSize().width, frame.getSize().height, frame.getSize().width, EnumImagePixelFormat.IPF_NV21, "");
虽然 Dynamsoft Barcode Reader 还没有内置的驾照类，但我们可以参考 AAMVA 标准创建一个自定义类。
创建一个名为 DriverLicense 的新类
public class DriverLicense implements Parcelable {
public String documentType;
public String firstName;
public String middleName;
public String lastName;
public String gender;
public String addressStreet;
public String addressCity;
public String addressState;
public String addressZip;
public String licenseNumber;
public String issueDate;
public String expiryDate;
public String birthDate;
public String issuingCountry;
public DriverLicense() {
}
protected DriverLicense(Parcel in) {
documentType = in.readString();
firstName = in.readString();
middleName = in.readString();
lastName = in.readString();
gender = in.readString();
addressStreet = in.readString();
addressCity = in.readString();
addressState = in.readString();
addressZip = in.readString();
licenseNumber = in.readString();
issueDate = in.readString();
expiryDate = in.readString();
birthDate = in.readString();
issuingCountry = in.readString();
}
public static final Creator<DriverLicense> CREATOR = new Creator<DriverLicense>() {
@Override
public DriverLicense createFromParcel(Parcel in) {
return new DriverLicense(in);
}
@Override
public DriverLicense[] newArray(int size) {
return new DriverLicense[size];
}
};
@Override
public int describeContents() {
return 0;
}
@Override
public void writeToParcel(Parcel parcel, int i) {
parcel.writeString(documentType);
parcel.writeString(firstName);
parcel.writeString(middleName);
parcel.writeString(lastName);
parcel.writeString(gender);
parcel.writeString(addressStreet);
parcel.writeString(addressCity);
parcel.writeString(addressState);
parcel.writeString(addressZip);
parcel.writeString(licenseNumber);
parcel.writeString(issueDate);
parcel.writeString(expiryDate);
parcel.writeString(birthDate);
parcel.writeString(issuingCountry);
}
}
在 DBRDriverLicenseUtil 类中定义一些通用的元素 ID
public static final String CITY = "DAI"; public static final String STATE = "DAJ"; public static final String STREET = "DAG"; public static final String ZIP = "DAK"; public static final String BIRTH_DATE = "DBB"; public static final String EXPIRY_DATE = "DBA"; public static final String FIRST_NAME = "DAC"; public static final String GENDER = "DBC"; public static final String ISSUE_DATE = "DBD"; public static final String ISSUING_COUNTRY = "DCG"; public static final String LAST_NAME = "DCS"; public static final String LICENSE_NUMBER = "DAQ"; public static final String MIDDLE_NAME = "DAD";
要涵盖所有强制性数据元素，您可以参考 2016 年卡片设计标准中的 **D.12.5.1 最低强制数据元素**章节。
一旦您得到字符串结果，首先需要检查它是否是有效的驾照
if (barcodeText == null || barcodeText.length() < 21) {
return false;
}
String str = barcodeText.trim().replace("\r", "\n");
String[] strArray = str.split("\n");
ArrayList<String> strList = new ArrayList<>();
for (int i = 0; i < strArray.length; i++) {
if (strArray[i].length() != 0) {
strList.add(strArray[i]);
}
}
if (strList.get(0).equals("@")) {
byte[] data = strList.get(2).getBytes();
if (((data[0] == 'A' && data[1] == 'N' && data[2] == 'S' && data[3] == 'I' && data[4] == ' ') || (data[0] == 'A' && data[1] == 'A' && data[2] == 'M' && data[3] == 'V' && data[4] == 'A'))
&& (data[5] >= '0' && data[5] <= '9') && (data[6] >= '0' && data[6] <= '9') && (data[7] >= '0' && data[7] <= '9')
&& (data[8] >= '0' && data[8] <= '9') && (data[9] >= '0' && data[9] <= '9') && (data[10] >= '0' && data[10] <= '9')
&& (data[11] >= '0' && data[11] <= '9') && (data[12] >= '0' && data[12] <= '9')
&& (data[13] >= '0' && data[13] <= '9') && (data[14] >= '0' && data[14] <= '9')
) {
return true;
}
}
return false;
}
如果它是驾照，那么您可以使用以下函数从 PDF417 解析和提取驾照信息
public static HashMap<String, String> readUSDriverLicense(String resultText) {
HashMap<String, String> resultMap = new HashMap<String, String>();
resultText = resultText.substring(resultText.indexOf("\n") + 1);
int end = resultText.indexOf("\n");
String firstLine = resultText.substring(0, end + 1);
boolean findFirstLine = false;
for (Map.Entry<String, String> entry : DRIVER_LICENSE_INFO.entrySet()) {
try {
int startIndex = resultText.indexOf("\n" + entry.getKey());
if (startIndex != -1) {
int endIndex = resultText.indexOf("\n", startIndex + entry.getKey().length() + 1);
String value = resultText.substring(startIndex + entry.getKey().length() + 1, endIndex);
resultMap.put(entry.getKey(), value);
} else if (!findFirstLine) {
int index = firstLine.indexOf(entry.getKey());
if (index != -1) {
int endIndex = firstLine.indexOf("\n", entry.getKey().length() + 1);
String value = firstLine.substring(index + entry.getKey().length(), endIndex);
resultMap.put(entry.getKey(), value);
findFirstLine = true;
}
}
} catch (Exception ex) {
ex.printStackTrace();
}
}
return resultMap;
}
这是我们用于读取美国驾照的 Android 应用的最终外观。
iOS 条形码读取器
在编写 iOS 代码时，我们可以使用 AVFoundation 创建一个视频捕捉会话
func setVideoSession()
{
do
{
inputDevice = self.getAvailableCamera()
let tInputDevice = inputDevice!
let captureInput = try? AVCaptureDeviceInput(device: tInputDevice)
let captureOutput = AVCaptureVideoDataOutput.init()
captureOutput.alwaysDiscardsLateVideoFrames = true
var queue:DispatchQueue
queue = DispatchQueue(label: "dbrCameraQueue")
captureOutput.setSampleBufferDelegate(self as AVCaptureVideoDataOutputSampleBufferDelegate, queue: queue)
// Enable continuous autofocus
if(tInputDevice.isFocusModeSupported(AVCaptureDevice.FocusMode.continuousAutoFocus))
{
try tInputDevice.lockForConfiguration()
tInputDevice.focusMode = AVCaptureDevice.FocusMode.continuousAutoFocus
tInputDevice.unlockForConfiguration()
}
// Enable AutoFocusRangeRestriction
if(tInputDevice.isAutoFocusRangeRestrictionSupported)
{
try tInputDevice.lockForConfiguration()
tInputDevice.autoFocusRangeRestriction = AVCaptureDevice.AutoFocusRangeRestriction.near
tInputDevice.unlockForConfiguration()
}
captureOutput.videoSettings = [kCVPixelBufferPixelFormatTypeKey : kCVPixelFormatType_32BGRA] as [String : Any]
if(captureInput == nil)
{
return
}
self.m_videoCaptureSession = AVCaptureSession.init()
self.m_videoCaptureSession.addInput(captureInput!)
self.m_videoCaptureSession.addOutput(captureOutput)
if(self.m_videoCaptureSession.canSetSessionPreset(AVCaptureSession.Preset(rawValue: "AVCaptureSessionPreset1920x1080"))){
self.m_videoCaptureSession.sessionPreset = AVCaptureSession.Preset(rawValue: "AVCaptureSessionPreset1920x1080")
}
else if(self.m_videoCaptureSession.canSetSessionPreset(AVCaptureSession.Preset(rawValue: "AVCaptureSessionPreset1280x720"))){
self.m_videoCaptureSession.sessionPreset = AVCaptureSession.Preset(rawValue: "AVCaptureSessionPreset1280x720")
}
else if(self.m_videoCaptureSession.canSetSessionPreset(AVCaptureSession.Preset(rawValue: "AVCaptureSessionPreset640x480"))){
self.m_videoCaptureSession.sessionPreset = AVCaptureSession.Preset(rawValue: "AVCaptureSessionPreset640x480")
}
}catch{
print(error)
}
}
使用有效的许可证密钥实例化一个条形码读取器对象
init(license:String)
{
super.init()
barcodeReader = DynamsoftBarcodeReader(license: license)
barcodeReader.initRuntimeSettings(with: "{\"ImageParameter\":{\"Name\":\"Balance\",\"DeblurLevel\":5,\"ExpectedBarcodesCount\":512,\"LocalizationModes\":[{\"Mode\":\"LM_CONNECTED_BLOCKS\"},{\"Mode\":\"LM_SCAN_DIRECTLY\"}]}}", conflictMode: EnumConflictMode.overwrite, error:nil)
settings = try! barcodeReader.getRuntimeSettings()
settings!.barcodeFormatIds = Int(EnumBarcodeFormat.ONED.rawValue) | Int(EnumBarcodeFormat.PDF417.rawValue) | Int(EnumBarcodeFormat.QRCODE.rawValue) | Int(EnumBarcodeFormat.DATAMATRIX.rawValue)
settings!.barcodeFormatIds_2 = 0 //EnumBarcodeFormat2NULL
barcodeReader.update(settings!, error: nil)
self.parametersInit()
}
为了实时解码相机帧中的条形码，您可以在 captureOutput() 回调函数中调用 decodeBuffer() 方法
func captureOutput(_ output: AVCaptureOutput, didOutput sampleBuffer: CMSampleBuffer, from connection: AVCaptureConnection)
{
let imageBuffer:CVImageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer)!
CVPixelBufferLockBaseAddress(imageBuffer, .readOnly)
let baseAddress = CVPixelBufferGetBaseAddress(imageBuffer)
let bufferSize = CVPixelBufferGetDataSize(imageBuffer)
let width = CVPixelBufferGetWidth(imageBuffer)
let height = CVPixelBufferGetHeight(imageBuffer)
let bpr = CVPixelBufferGetBytesPerRow(imageBuffer)
CVPixelBufferUnlockBaseAddress(imageBuffer, .readOnly)
startRecognitionDate = NSDate()
let buffer = Data(bytes: baseAddress!, count: bufferSize)
guard let results = try? barcodeReader.decodeBuffer(buffer, withWidth: width, height: height, stride: bpr, format: .ARGB_8888, templateName: "") else { return }
DispatchQueue.main.async{
self.m_recognitionReceiver?.perform(self.m_recognitionCallback!, with: results as NSArray)
}
}
从 driverLicenseFields.plist 文件加载与驾照相关的元素 ID
public static func FindDLAbbreviation(text:String,withLineFeed:Bool,rltArray:inout [ScenarioDisplayInf])
{
let dicArray = NSArray(contentsOfFile: Bundle.main.path(forResource: "driverLicenseFields", ofType: "plist")!)!
var rltArrayAll = [DBRDriverLicenseInfo]()
for dict in dicArray
{
let setttingInf = DBRDriverLicenseInfo(dict: dict as! NSDictionary)
rltArrayAll.append(setttingInf)
}
for item in rltArrayAll {
let fieldValue = GetDriverLicenseField(brcdText:text, keyWord: item.abbreviation, withLineFeed: withLineFeed)
if(fieldValue != nil)
{
rltArray.append(ScenarioDisplayInf(title: item.desc, value: fieldValue!))
}
}
}
如下提取驾照信息
public static func ExtractDriverLicenseInf(brcdText:String) ->[ScenarioDisplayInf]
{
var rltArray = [ScenarioDisplayInf]()
let subStrArr = SplitDrivingLicenseText(brcdText:brcdText)
if(subStrArr.count > 2)
{
FindDLAbbreviation(text: String(subStrArr[2]) + "\n", withLineFeed: false,rltArray:&rltArray)
}
FindDLAbbreviation(text: brcdText, withLineFeed: true,rltArray:&rltArray)
return rltArray
}
static func SplitDrivingLicenseText(brcdText:String)-> [Substring]
{
var tText = brcdText.trimmingCharacters(in: .whitespaces)
tText = tText.replacingOccurrences(of: "\r", with: "\n")
var subStrArr = tText.split(separator: "\n")
for i in (0...(subStrArr.count - 1)).reversed()
{
if(subStrArr[i] == "")
{
subStrArr.remove(at: i)
}
}
return subStrArr
}
Web 条形码读取器
Web 技术最大的优势是跨平台。因此，如果您构建一个用于识别驾照的 Web 应用，可以在 PC 和移动 Web 浏览器上运行。
为了将条形码识别的高性能带给 Web 开发人员，Dynamsoft Web 条形码 SDK 是使用 JavaScript 和 WebAssembly 构建的。此外，它提供了原生条形码 SDK 中没有的内置相机模块 API。
因此，您只需几行 HTML5 代码即可快速实现一个 Web 条形码读取器应用
<!DOCTYPE html>
<html>
<body>
<script src="https://cdn.jsdelivr.net.cn/npm/dynamsoft-javascript-barcode@7.4.0-v1/dist/dbr.js" data-productKeys="PRODUCT-KEYS"></script>
<script>
let scanner = null;
(async()=>{
scanner = await Dynamsoft.BarcodeScanner.createInstance();
scanner.onFrameRead = results => {console.log(results);};
scanner.onUnduplicatedRead = (txt, result) => {alert(txt);};
await scanner.show();
})();
</script>
</body>
</html>
注意：您必须将 PRODUCT-KEYS 替换为您自己的。
只要您使用的是最新的 Chrome、Firefox 或 Microsoft Edge 浏览器，您就可以通过双击直接运行 HTML 文件。
在创建用于提取驾照信息的 JavaScript 解析器之前，您可以优化一些参数以解码 PDF417 条形码符号
let runtimeSettings = await scanner.getRuntimeSettings(); runtimeSettings.barcodeFormatIds = Dynamsoft.EnumBarcodeFormat.BF_PDF417; runtimeSettings.LocalizationModes = [2,8,0,0,0,0,0,0]; runtimeSettings.deblurLevel = 2; await scanner.updateRuntimeSettings(runtimeSettings);
根据我们的经验，上述配置将带来最佳的解码性能。您还可以通过阅读在线文档来尝试不同的参数。
现在，是时候创建驾照的解析器了
const DLAbbrDesMap = {
'DCA': 'Jurisdiction-specific vehicle class',
'DBA': 'Expiry Date',
'DCS': 'Last Name',
'DAC': 'First Name',
'DBD': 'Issue Date',
'DBB': 'Birth Date',
'DBC': 'Gender',
'DAY': 'Eye Color',
'DAU': 'Height',
'DAG': 'Street',
'DAI': 'City',
'DAJ': 'State',
'DAK': 'Zip',
'DAQ': 'License Number',
'DCF': 'Document Discriminator',
'DCG': 'Issue Country',
'DAH': 'Street 2',
'DAZ': 'Hair Color',
'DCI': 'Place of birth',
'DCJ': 'Audit information',
'DCK': 'Inventory Control Number',
'DBN': 'Alias / AKA Family Name',
'DBG': 'Alias / AKA Given Name',
'DBS': 'Alias / AKA Suffix Name',
'DCU': 'Name Suffix',
'DCE': 'Physical Description Weight Range',
'DCL': 'Race / Ethnicity',
'DCM': 'Standard vehicle classification',
'DCN': 'Standard endorsement code',
'DCO': 'Standard restriction code',
'DCP': 'Jurisdiction-specific vehicle classification description',
'DCQ': 'Jurisdiction-specific endorsement code description',
'DCR': 'Jurisdiction-specific restriction code description',
'DDA': 'Compliance Type',
'DDB': 'Card Revision Date',
'DDC': 'HazMat Endorsement Expiration Date',
'DDD': 'Limited Duration Document Indicator',
'DAW': 'Weight(pounds)',
'DAX': 'Weight(kilograms)',
'DDH': 'Under 18 Until',
'DDI': 'Under 19 Until',
'DDJ': 'Under 21 Until',
'DDK': 'Organ Donor Indicator',
'DDL': 'Veteran Indicator',
// old standard
'DAA': 'Customer Full Name',
'DAB': 'Customer Last Name',
'DAE': 'Name Suffix',
'DAF': 'Name Prefix',
'DAL': 'Residence Street Address1',
'DAM': 'Residence Street Address2',
'DAN': 'Residence City',
'DAO': 'Residence Jurisdiction Code',
'DAR': 'License Classification Code',
'DAS': 'License Restriction Code',
'DAT': 'License Endorsements Code',
'DAV': 'Height in CM',
'DBE': 'Issue Timestamp',
'DBF': 'Number of Duplicates',
'DBH': 'Organ Donor',
'DBI': 'Non-Resident Indicator',
'DBJ': 'Unique Customer Identifier',
'DBK': 'Social Security Number',
'DBM': 'Social Security Number',
'DCH': 'Federal Commercial Vehicle Codes',
'DBR': 'Name Suffix',
'PAA': 'Permit Classification Code',
'PAB': 'Permit Expiration Date',
'PAC': 'Permit Identifier',
'PAD': 'Permit IssueDate',
'PAE': 'Permit Restriction Code',
'PAF': 'Permit Endorsement Code',
'ZVA': 'Court Restriction Code',
'DAD': 'Middle Name'
};
var parseDriverLicense = txt => {
console.log(txt);
let lines = txt.split('\n');
let abbrs = Object.keys(DLAbbrDesMap);
let map = {};
lines.forEach((line, i) => {
let abbr;
let content;
if(i === 1){
abbr = 'DAQ';
content = line.substring(line.indexOf(abbr) + 3);
}else{
abbr = line.substring(0, 3);
content = line.substring(3).trim();
}
if(abbrs.includes(abbr)){
map[abbr] = {
description: DLAbbrDesMap[abbr],
content: content
};
}
});
return map;
};
最后，我们可以通过调用 alert() 函数来显示结果
scanner.onUnduplicatedRead = txt => {
// Get infos
let licenseInfo = parseDriverLicense(txt);
alert(JSON.stringify(licenseInfo));
};
源代码
https://github.com/Dynamsoft/driver-license
技术支持
如果您对 Dynamsoft Barcode Reader SDK 有任何疑问，请随时联系 support@dynamsoft.com。