How to Build an Android MRZ Scanner with USB Camera and Dynamsoft Label Recognizer
Mar 19, 2026
In the previous article, we talked about how to scan barcodes using a USB camera on an Android device. In this article, we are going to scan MRZ (machine-readable zone) on passports and ID cards with Dynamsoft Label Recognizer.
Here is a video of the result:
What you’ll build: A real-time Android MRZ scanner that reads passport and ID card machine-readable zones via a connected USB camera using Dynamsoft Label Recognizer.
Key Takeaways
- Dynamsoft Label Recognizer’s
CaptureVisionRoutercan scan MRZ from bitmap frames captured directly from a USB camera preview on Android. - The UVCCamera library (
libuvccamera.aar) enables USB camera access on Android without root, andUVCCameraHandlersimplifies preview and frame capture. - A
Timerpolling at 100 ms intervals provides continuous MRZ recognition on YUYV camera streams at 640×480 minimum resolution. - On Android 9+, the UVCCamera library requires
targetSdkVersion≤ 27 to function correctly.
Common Developer Questions
- How do I scan a passport MRZ using a USB camera on Android?
- What resolution does an Android USB camera need for reliable MRZ recognition?
- Why does my UVCCamera preview not work on Android 9 or higher?
Prerequisites
- Android Studio installed with a Java project template
- A UVC-compatible USB camera
- Get a 30-day free trial license for Dynamsoft Label Recognizer
Step 1: Create a New Android Project
Open Android Studio to create a new Java project.
Step 2: Add Required Dependencies
-
Add the UVCCamera library.
-
Download the following AARs and put them in the
app/libsfolder. -
In
settings.gradle, add the following lines:dependencyResolutionManagement { repositories { google() mavenCentral() maven { url 'https://raw.github.com/saki4510t/libcommon/master/repository/' } flatDir { dirs 'libs' } } } -
In the app’s
build.gradle, add the following lines:dependencies { implementation fileTree(dir: 'libs', include: ['*.aar','*.jar']) implementation("com.serenegiant:common:1.5.20") { exclude module: 'support-v4' } } -
You may also need to enable Jetifier in
gradle.properties.android.enableJetifier=true
-
-
Add the Dynamsoft SDK.
-
In
settings.gradle, add the following lines:dependencyResolutionManagement { repositoriesMode.set(RepositoriesMode.FAIL_ON_PROJECT_REPOS) repositories { maven { url "https://download2.dynamsoft.com/maven/aar" } } } -
In the app’s
build.gradle, add the following lines:dependencies { implementation "com.dynamsoft:dynamsoftcapturevisionbundle:2.6.1002" implementation 'com.dynamsoft:dynamsoftmrz:3.4.20' }
-
Step 3: Open the USB Camera
Let’s do the following to open the connected USB camera.
Add Camera Preview Controls
Add a UVCCameraTextureView for camera preview and an ImageButton to select and open cameras.
XML:
<com.serenegiant.widget.UVCCameraTextureView
android:id="@+id/camera_view"
android:layout_width="407dp"
android:layout_height="720dp"
android:layout_centerInParent="true"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<ImageButton
android:id="@+id/imageButton"
android:layout_width="50dp"
android:layout_height="50dp"
android:layout_marginBottom="16dp"
android:background="@android:color/transparent"
android:scaleType="fitCenter"
android:src="@android:drawable/ic_menu_camera"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent" />
In MainActivity:
private CameraViewInterface mUVCCameraView;
private ImageButton mCameraButton;
@Override
protected void onCreate(final Bundle savedInstanceState) {
//......
mCameraButton = findViewById(R.id.imageButton);
final View view = findViewById(R.id.camera_view);
mUVCCameraView = (CameraViewInterface)view;
}
Monitor USB Connection Events
-
Initialize a USBMonitor instance.
private USBMonitor mUSBMonitor; @Override protected void onCreate(Bundle savedInstanceState) { //...... mUSBMonitor = new USBMonitor(this, mOnDeviceConnectListener); } private final USBMonitor.OnDeviceConnectListener mOnDeviceConnectListener = new USBMonitor.OnDeviceConnectListener() { @Override public void onAttach(final UsbDevice device) { Toast.makeText(MainActivity.this, "USB_DEVICE_ATTACHED", Toast.LENGTH_SHORT).show(); } @Override public void onConnect(final UsbDevice device, final USBMonitor.UsbControlBlock ctrlBlock, final boolean createNew) { } @Override public void onDisconnect(final UsbDevice device, final USBMonitor.UsbControlBlock ctrlBlock) { } @Override public void onDettach(final UsbDevice device) { Toast.makeText(MainActivity.this, "USB_DEVICE_DETACHED", Toast.LENGTH_SHORT).show(); } @Override public void onCancel(final UsbDevice device) { } }; -
Manage the life cycle.
@Override protected void onStart() { super.onStart(); mUSBMonitor.register(); } @Override protected void onStop() { mUSBMonitor.unregister(); super.onStop(); } @Override public void onDestroy() { if (mUSBMonitor != null) { mUSBMonitor.destroy(); mUSBMonitor = null; } super.onDestroy(); }
Start the Camera Preview
The UVCCameraHandler class is used to handle USB cameras.
-
Initialize the handler.
/** * set true if you want to record movie using MediaSurfaceEncoder * (writing frame data into Surface camera from MediaCodec * by almost same way as USBCameratest2) * set false if you want to record movie using MediaVideoEncoder */ private static final boolean USE_SURFACE_ENCODER = false; /** * preview resolution(width) * if your camera does not support specific resolution and mode, * {@link UVCCamera#setPreviewSize(int, int, int)} throw exception */ private static final int PREVIEW_WIDTH = 640; // 640 /** * preview resolution(height) * if your camera does not support specific resolution and mode, * {@link UVCCamera#setPreviewSize(int, int, int)} throw exception */ private static final int PREVIEW_HEIGHT = 480; //480 /** * preview mode * if your camera does not support specific resolution and mode, * {@link UVCCamera#setPreviewSize(int, int, int)} throw exception * 0:YUYV, other:MJPEG */ private static final int PREVIEW_MODE = 0; // YUV private UVCCameraHandler mCameraHandler; @Override protected void onCreate(Bundle savedInstanceState) { //...... mCameraHandler = UVCCameraHandler.createHandler(this, mUVCCameraView, USE_SURFACE_ENCODER ? 0 : 1, PREVIEW_WIDTH, PREVIEW_HEIGHT, PREVIEW_MODE); } -
Add an
OnClickListenerfor the image button to start a camera selection dialog. The preview will be started after a camera is chosen.protected void onCreate(Bundle savedInstanceState) { //...... mCameraButton.setOnClickListener(mOnClickListener); //...... } private final View.OnClickListener mOnClickListener = new View.OnClickListener() { @Override public void onClick(final View view) { if ((mCameraHandler != null) && !mCameraHandler.isOpened()) { CameraDialog.showDialog(MainActivity.this); } else { mCameraHandler.close(); } } }; private final USBMonitor.OnDeviceConnectListener mOnDeviceConnectListener = new USBMonitor.OnDeviceConnectListener() { @Override public void onConnect(final UsbDevice device, final USBMonitor.UsbControlBlock ctrlBlock, final boolean createNew) { if (mCameraHandler != null) { mCameraHandler.open(ctrlBlock); startPreview(); } } } private void startPreview() { if (mCameraHandler != null) { final SurfaceTexture st = mUVCCameraView.getSurfaceTexture(); mCameraHandler.startPreview(new Surface(st)); } }The activity has to be modified as well to implements the library’s
CameraDialogParent:public class MainActivity extends BaseActivity implements CameraDialog.CameraDialogParentYou may find that the preview is distorted to fill the screen. You can keep its aspect ratio using the following code:
mUVCCameraView.setAspectRatio(PREVIEW_WIDTH / (double)PREVIEW_HEIGHT);
Step 4: Read MRZ from the USB Camera Preview
Now that we can show camera preview, we can use Dynamsoft Label Recognizer to scan MRZ.
Initialize Dynamsoft Label Recognizer
Initialize the SDK with a license key obtained from the Prerequisites section above.
private CaptureVisionRouter mRouter; //used to call Dynamsoft Label Recognizer to recognize MRZ
private CodeParser mParser; //used to parse the recognized MRZ
protected void onCreate(Bundle savedInstanceState) {
//......
if (savedInstanceState == null) {
LicenseManager.initLicense("LICENSE-KEY", this, (isSuccess, error) -> {
if (!isSuccess) {
error.printStackTrace();
}
});
}
mRouter = new CaptureVisionRouter(this);
mParser = new CodeParser(this);
}
Configure MRZ Recognition Settings
We need to update the default settings for MRZ recognition with the following JSON template.
private void initMRZSettings(){
String template = """
{
"CaptureVisionTemplates": [
{
"Name": "Default"
},
{
"Name": "ReadBarcodes_Default",
"ImageROIProcessingNameArray": [
"roi_read_barcodes"
],
"Timeout": 200,
"MaxParallelTasks":0
},
{
"Name": "RecognizeTextLines_Default",
"ImageROIProcessingNameArray": [
"roi_recognize_number_letter"
],
"MaxParallelTasks":0
},
{
"Name": "DetectDocumentBoundaries_Default",
"ImageROIProcessingNameArray": [
"roi_detect_document_boundaries"
]
},
{
"Name": "DetectAndNormalizeDocument_Default",
"ImageROIProcessingNameArray": [
"roi_detect_and_normalize_document"
]
},
{
"Name": "NormalizeDocument_Default",
"ImageROIProcessingNameArray": [
"roi_normalize_document"
]
},
{
"Name": "ReadBarcodes_SpeedFirst",
"ImageROIProcessingNameArray": [
"roi_read_barcodes_speed_first"
],
"Timeout": 500
},
{
"Name": "ReadBarcodes_ReadRateFirst",
"ImageROIProcessingNameArray": [
"roi_read_barcodes_read_rate"
],
"Timeout": 5000
},
{
"Name": "ReadSingleBarcode",
"ImageROIProcessingNameArray": [
"roi_read_single_barcode"
],
"Timeout": 200,
"MaxParallelTasks":0
},
{
"Name": "RecognizeNumbers",
"ImageROIProcessingNameArray": [
"roi_recognize_number"
],
"MaxParallelTasks":0
},
{
"Name": "RecognizeLetters",
"ImageROIProcessingNameArray": [
"roi_recognize_letter"
],
"MaxParallelTasks":0
},
{
"Name": "RecognizeUppercaseLetters",
"ImageROIProcessingNameArray": [
"roi_recognize_uppercase"
],
"MaxParallelTasks":0
},
{
"Name": "RecognizeNumbersAndUppercaseLetters",
"ImageROIProcessingNameArray": [
"roi_recognize_number_uppercase"
],
"MaxParallelTasks":0
},
{
"Name": "RecognizeNumbersAndLetters",
"ImageROIProcessingNameArray": [
"roi_recognize_number_letter"
],
"MaxParallelTasks":0
},
{
"Name": "ReadPassportAndId",
"OutputOriginalImage": 0,
"ImageROIProcessingNameArray": [
"roi_passport_and_id"
],
"Timeout": 2000
},
{
"Name": "ReadPassport",
"OutputOriginalImage": 0,
"ImageROIProcessingNameArray": [
"roi_passport"
],
"Timeout": 2000
},
{
"Name": "ReadId",
"OutputOriginalImage": 0,
"ImageROIProcessingNameArray": [
"roi_id"
],
"Timeout": 2000
},
{
"Name" : "ReadDriversLicense",
"ImageROIProcessingNameArray" :
[
"roi_pdf_417"
],
"SemanticProcessingNameArray": [ "sp_pdf_417" ],
"Timeout" : 10000
},
{
"Name": "ReadVIN",
"ImageROIProcessingNameArray": [
"roi_vin_barcode",
"roi_vin_text"
],
"MaxParallelTasks": 4,
"SemanticProcessingNameArray": [
"sp_vin_barcode",
"sp_vin_text"
],
"Timeout": 10000
},
{
"Name" : "ReadVINBarcode",
"ImageROIProcessingNameArray" :
[
"roi_vin_barcode"
],
"MaxParallelTasks" : 4,
"SemanticProcessingNameArray": [ "sp_vin_barcode" ],
"Timeout" : 10000
},
{
"Name" : "ReadVINText",
"ImageROIProcessingNameArray" :
[
"roi_vin_text"
],
"MaxParallelTasks" : 4,
"SemanticProcessingNameArray": [ "sp_vin_text" ],
"Timeout" : 10000
}
],
"TargetROIDefOptions": [
{
"Name": "roi_read_barcodes",
"TaskSettingNameArray": [
"task_read_barcodes"
]
},
{
"Name": "roi_detect_document_boundaries",
"TaskSettingNameArray": [
"task_detect_document_boundaries"
]
},
{
"Name": "roi_detect_and_normalize_document",
"TaskSettingNameArray": [
"task_detect_and_normalize_document"
]
},
{
"Name": "roi_normalize_document",
"TaskSettingNameArray": [
"task_normalize_document"
]
},
{
"Name": "roi_read_barcodes_speed_first",
"TaskSettingNameArray": [
"task_read_barcodes_speed_first"
]
},
{
"Name": "roi_read_barcodes_read_rate",
"TaskSettingNameArray": [
"task_read_barcodes_read_rate"
]
},
{
"Name": "roi_read_single_barcode",
"TaskSettingNameArray": [
"task_read_single_barcode"
]
},
{
"Name": "roi_recognize_number",
"TaskSettingNameArray": [
"task_recognize_number"
]
},
{
"Name": "roi_recognize_letter",
"TaskSettingNameArray": [
"task_recognize_letter"
]
},
{
"Name": "roi_recognize_uppercase",
"TaskSettingNameArray": [
"task_recognize_uppercase"
]
},
{
"Name": "roi_recognize_number_uppercase",
"TaskSettingNameArray": [
"task_recognize_number_uppercase"
]
},
{
"Name": "roi_recognize_number_letter",
"TaskSettingNameArray": [
"task_recognize_number_letter"
]
},
{
"Name": "roi_passport_and_id",
"TaskSettingNameArray": [
"task_passport_and_id"
]
},
{
"Name": "roi_passport",
"TaskSettingNameArray": [
"task_passport"
]
},
{
"Name": "roi_id",
"TaskSettingNameArray": [
"task_id"
]
},
{
"Name" : "roi_pdf_417",
"TaskSettingNameArray" :
[
"task_pdf_417"
]
},
{
"Name" : "roi_vin_barcode",
"TaskSettingNameArray" :
[
"task_vin_barcode"
]
},
{
"Name" : "roi_vin_text",
"TaskSettingNameArray" :
[
"task_vin_text"
]
}
],
"BarcodeFormatSpecificationOptions": [
{
"Name": "bfs1",
"BarcodeFormatIds": [
"BF_PDF417",
"BF_QR_CODE",
"BF_DATAMATRIX",
"BF_AZTEC",
"BF_MICRO_QR",
"BF_MICRO_PDF417",
"BF_DOTCODE"
],
"MirrorMode": "MM_BOTH"
},
{
"Name": "bfs2",
"BarcodeFormatIds": [
"BF_ALL"
],
"MirrorMode": "MM_NORMAL"
},
{
"Name": "bfs1_speed_first",
"BaseBarcodeFormatSpecification": "bfs1"
},
{
"Name": "bfs2_speed_first",
"BaseBarcodeFormatSpecification": "bfs2"
},
{
"Name": "bfs1_read_rate_first",
"BaseBarcodeFormatSpecification": "bfs1"
},
{
"Name": "bfs2_read_rate_first",
"BaseBarcodeFormatSpecification": "bfs2"
},
{
"Name": "bfs1_single_barcode",
"BaseBarcodeFormatSpecification": "bfs1"
},
{
"Name": "bfs2_single_barcode",
"BaseBarcodeFormatSpecification": "bfs2"
},
{
"BarcodeFormatIds" :
[
"BF_CODE_39_EXTENDED"
],
"BarcodeTextRegExPattern" : "(I{0,1})([0-9A-HJ-NPR-Z]{9}[1-9A-HJ-NPR-TV-Y][0-9A-HJ-NPR-Z]{2}[0-9]{5})",
"MirrorMode" : "MM_NORMAL",
"ModuleSizeRangeArray" : null,
"Name" : "VIN_CODE_39_EXTENDED"
},
{
"BarcodeFormatIds" :
[
"BF_DATAMATRIX"
],
"BarcodeTextRegExPattern" : "[0-9A-HJ-NPR-Z]{9}[1-9A-HJ-NPR-TV-Y][0-9A-HJ-NPR-Z]{2}[0-9]{5}",
"Name" : "VIN_DATAMATRIX"
},
{
"BarcodeFormatIds" :
[
"BF_QR_CODE"
],
"Name" : "VIN_QR_CODE"
}
],
"BarcodeReaderTaskSettingOptions": [
{
"Name": "task_read_barcodes",
"ExpectedBarcodesCount" : 1,
"BaseBarcodeReaderTaskSettingName": "task_read_single_barcode",
"BarcodeFormatSpecificationNameArray": [
"bfs1",
"bfs2"
],
"LocalizationModes": [
{
"Mode": "LM_CONNECTED_BLOCKS"
},
{
"Mode": "LM_LINES"
}
],
"SectionImageParameterArray": [
{
"Section": "ST_REGION_PREDETECTION",
"ImageParameterName": "ip_read_barcodes"
},
{
"Section": "ST_BARCODE_LOCALIZATION",
"ImageParameterName": "ip_read_barcodes"
},
{
"Section": "ST_BARCODE_DECODING",
"ImageParameterName": "ip_read_barcodes"
}
]
},
{
"Name": "task_read_barcodes_speed_first",
"ExpectedBarcodesCount" : 0,
"BarcodeFormatIds" : [ "BF_DEFAULT" ],
"LocalizationModes": [
{
"Mode": "LM_CONNECTED_BLOCKS"
}
],
"DeblurModes":[
{
"Mode": "DM_BASED_ON_LOC_BIN"
},
{
"Mode": "DM_THRESHOLD_BINARIZATION"
},
{
"Mode": "DM_DEEP_ANALYSIS"
}
],
"BarcodeFormatSpecificationNameArray": [
"bfs1_speed_first",
"bfs2_speed_first"
],
"SectionImageParameterArray": [
{
"Section": "ST_REGION_PREDETECTION",
"ImageParameterName": "ip_read_barcodes_speed_first"
},
{
"Section": "ST_BARCODE_LOCALIZATION",
"ImageParameterName": "ip_read_barcodes_speed_first"
},
{
"Section": "ST_BARCODE_DECODING",
"ImageParameterName": "ip_read_barcodes_speed_first"
}
]
},
{
"Name": "task_read_barcodes_read_rate",
"ExpectedBarcodesCount" : 999,
"BarcodeFormatIds" : [ "BF_DEFAULT" ],
"LocalizationModes": [
{
"Mode" : "LM_CONNECTED_BLOCKS"
},
{
"Mode" : "LM_LINES"
},
{
"Mode" : "LM_STATISTICS"
}
],
"DeblurModes":[
{
"Mode": "DM_BASED_ON_LOC_BIN"
},
{
"Mode": "DM_THRESHOLD_BINARIZATION"
},
{
"Mode": "DM_DIRECT_BINARIZATION"
},
{
"Mode": "DM_SMOOTHING"
},
{
"Mode": "DM_DEEP_ANALYSIS"
}
],
"BarcodeFormatSpecificationNameArray": [
"bfs1_read_rate_first",
"bfs2_read_rate_first"
],
"SectionImageParameterArray": [
{
"Section": "ST_REGION_PREDETECTION",
"ImageParameterName": "ip_read_barcodes_read_rate"
},
{
"Section": "ST_BARCODE_LOCALIZATION",
"ImageParameterName": "ip_read_barcodes_read_rate"
},
{
"Section": "ST_BARCODE_DECODING",
"ImageParameterName": "ip_read_barcodes_read_rate"
}
]
},
{
"Name": "task_read_single_barcode",
"ExpectedBarcodesCount":1,
"LocalizationModes": [
{
"Mode": "LM_SCAN_DIRECTLY",
"ScanDirection": 2
},
{
"Mode": "LM_CONNECTED_BLOCKS"
}
],
"DeblurModes":[
{
"Mode": "DM_BASED_ON_LOC_BIN"
},
{
"Mode": "DM_THRESHOLD_BINARIZATION"
},
{
"Mode": "DM_DEEP_ANALYSIS"
}
],
"BarcodeFormatSpecificationNameArray": [
"bfs1_single_barcode",
"bfs2_single_barcode"
],
"SectionImageParameterArray": [
{
"Section": "ST_REGION_PREDETECTION",
"ImageParameterName": "ip_read_single_barcode"
},
{
"Section": "ST_BARCODE_LOCALIZATION",
"ImageParameterName": "ip_read_single_barcode"
},
{
"Section": "ST_BARCODE_DECODING",
"ImageParameterName": "ip_read_single_barcode"
}
]
},
{
"Name" : "task_pdf_417",
"BarcodeColourModes" :
[
{
"LightReflection" : 1,
"Mode" : "BICM_DARK_ON_LIGHT"
}
],
"BarcodeFormatIds" :
[
"BF_PDF417"
],
"DeblurModes" : null,
"ExpectedBarcodesCount" : 1,
"LocalizationModes" :
[
{
"Mode" : "LM_CONNECTED_BLOCKS"
},
{
"Mode" : "LM_LINES"
},
{
"Mode" : "LM_STATISTICS"
}
],
"SectionImageParameterArray" :
[
{
"ContinueWhenPartialResultsGenerated" : 1,
"ImageParameterName" : "ip_localize_pdf417",
"Section" : "ST_REGION_PREDETECTION"
},
{
"ContinueWhenPartialResultsGenerated" : 1,
"ImageParameterName" : "ip_localize_pdf417",
"Section" : "ST_BARCODE_LOCALIZATION"
},
{
"ContinueWhenPartialResultsGenerated" : 1,
"ImageParameterName" : "ip_decode_pdf417",
"Section" : "ST_BARCODE_DECODING"
}
]
},
{
"Name" : "task_vin_barcode",
"DeblurModes" : null,
"BarcodeColourModes" :
[
{
"LightReflection" : 1,
"Mode" : "BICM_DARK_ON_LIGHT"
}
],
"BarcodeFormatIds" :
[
"BF_CODE_39_EXTENDED",
"BF_QR_CODE",
"BF_DATAMATRIX"
],
"BarcodeFormatSpecificationNameArray" :
[
"VIN_CODE_39_EXTENDED",
"VIN_QR_CODE",
"VIN_DATAMATRIX"
],
"DeformationResistingModes" :
[
{
"BinarizationMode" :
{
"BinarizationThreshold" : -1,
"BlockSizeX" : 0,
"BlockSizeY" : 0,
"EnableFillBinaryVacancy" : 0,
"GrayscaleEnhancementModesIndex" : -1,
"Mode" : "BM_LOCAL_BLOCK",
"MorphOperation" : "Close",
"MorphOperationKernelSizeX" : -1,
"MorphOperationKernelSizeY" : -1,
"MorphShape" : "Rectangle",
"ThresholdCompensation" : 10
},
"GrayscaleEnhancementMode" :
{
"Mode" : "GEM_GENERAL",
"Sensitivity" : -1,
"SharpenBlockSizeX" : -1,
"SharpenBlockSizeY" : -1,
"SmoothBlockSizeX" : -1,
"SmoothBlockSizeY" : -1
},
"Level" : 5,
"Mode" : "DRM_SKIP"
}
],
"ExpectedBarcodesCount" : 1,
"LocalizationModes" :
[
{
"Mode" : "LM_CONNECTED_BLOCKS"
},
{
"Mode" : "LM_SCAN_DIRECTLY"
}
],
"SectionImageParameterArray" :
[
{
"ContinueWhenPartialResultsGenerated" : 1,
"ImageParameterName" : "ip_localize_vin",
"Section" : "ST_REGION_PREDETECTION"
},
{
"ContinueWhenPartialResultsGenerated" : 1,
"ImageParameterName" : "ip_localize_vin",
"Section" : "ST_BARCODE_LOCALIZATION"
},
{
"ContinueWhenPartialResultsGenerated" : 1,
"ImageParameterName" : "ip_decode_vin",
"Section" : "ST_BARCODE_DECODING"
}
]
}
],
"TextLineSpecificationOptions": [
{
"Name": "tls_number_letter",
"CharacterModelName" : "NumberLetter",
"OutputResults": 1
},
{
"Name": "tls_number",
"CharacterModelName" : "Number",
"OutputResults": 1
},
{
"Name": "tls_letter",
"CharacterModelName" : "Letter",
"OutputResults": 1
},
{
"Name": "tls_uppercase",
"CharacterModelName" : "Uppercase",
"OutputResults": 1
},
{
"Name": "tls_number_uppercase",
"CharacterModelName" : "NumberUppercase",
"OutputResults": 1
},
{
"Name": "tls_mrz_passport",
"BaseTextLineSpecificationName": "tls_base",
"StringLengthRange": [ 44, 44 ],
"OutputResults": 1,
"ExpectedGroupsCount": 1,
"ConcatResults": 1,
"ConcatSeparator": "\\n",
"SubGroups": [
{
"StringRegExPattern": "(P[A-Z<][A-Z<]{3}[A-Z<]{39}){(44)}",
"StringLengthRange": [ 44, 44 ],
"BaseTextLineSpecificationName": "tls_base"
},
{
"StringRegExPattern": "([A-Z0-9<]{9}[0-9][A-Z<]{3}[0-9]{2}[(01-12)][(01-31)][0-9][MF<][0-9]{2}[(01-12)][(01-31)][0-9][A-Z0-9<]{14}[0-9<][0-9]){(44)}",
"StringLengthRange": [ 44, 44 ],
"BaseTextLineSpecificationName": "tls_base"
}
]
},
{
"Name": "tls_mrz_id_td2",
"BaseTextLineSpecificationName": "tls_base",
"StringLengthRange": [ 36, 36 ],
"OutputResults": 1,
"ExpectedGroupsCount": 1,
"ConcatResults": 1,
"ConcatSeparator": "\\n",
"SubGroups": [
{
"StringRegExPattern": "([ACI][A-Z<][A-Z<]{3}[A-Z<]{31}){(36)}",
"StringLengthRange": [ 36, 36 ],
"BaseTextLineSpecificationName": "tls_base"
},
{
"StringRegExPattern": "([A-Z0-9<]{9}[0-9][A-Z<]{3}[0-9]{2}[(01-12)][(01-31)][0-9][MF<][0-9]{2}[(01-12)][(01-31)][0-9][A-Z0-9<]{8}){(36)}",
"StringLengthRange": [ 36, 36 ],
"BaseTextLineSpecificationName": "tls_base"
}
]
},
{
"Name": "tls_mrz_id_td1",
"BaseTextLineSpecificationName": "tls_base",
"StringLengthRange": [ 30, 30 ],
"OutputResults": 1,
"ExpectedGroupsCount": 1,
"ConcatResults": 1,
"ConcatSeparator": "\\n",
"SubGroups": [
{
"StringRegExPattern": "([ACI][A-Z<][A-Z<]{3}[A-Z0-9<]{9}[0-9<][A-Z0-9<]{15}){(30)}",
"StringLengthRange": [ 30, 30 ],
"BaseTextLineSpecificationName": "tls_base"
},
{
"StringRegExPattern": "([0-9]{2}[(01-12)][(01-31)][0-9][MF<][0-9]{2}[(01-12)][(01-31)][0-9][A-Z<]{3}[A-Z0-9<]{11}[0-9]){(30)}",
"StringLengthRange": [ 30, 30 ],
"BaseTextLineSpecificationName": "tls_base"
},
{
"StringRegExPattern": "([A-Z<]{30}){(30)}",
"StringLengthRange": [ 30, 30 ],
"BaseTextLineSpecificationName": "tls_base"
}
]
},
{
"Name": "tls_base",
"CharacterModelName": "MRZ",
"CharHeightRange": [ 5, 1000, 1 ],
"BinarizationModes": [
{
"BlockSizeX": 30,
"BlockSizeY": 30,
"Mode": "BM_LOCAL_BLOCK",
"EnableFillBinaryVacancy": 0,
"ThresholdCompensation": 15
}
],
"ConfusableCharactersCorrection": {
"ConfusableCharacters": [
[ "0", "O" ],
[ "1", "I" ],
[ "5", "S" ]
],
"FontNameArray": [ "OCR_B" ]
}
},
{
"Name": "tls_vin_text",
"CharacterModelName": "VIN",
"StringRegExPattern": "[0-9A-HJ-NPR-Z]{9}[1-9A-HJ-NPR-TV-Y][0-9A-HJ-NPR-Z]{2}[0-9]{5}",
"CharHeightRange": [5, 1000, 1],
"StringLengthRange": [17, 17]
}
],
"LabelRecognizerTaskSettingOptions": [
{
"Name": "task_recognize_number_letter",
"TextLineSpecificationNameArray": [
"tls_number_letter"
],
"SectionImageParameterArray": [
{
"Section": "ST_REGION_PREDETECTION",
"ImageParameterName": "ip_recognize_number_letter"
},
{
"Section": "ST_TEXT_LINE_LOCALIZATION",
"ImageParameterName": "ip_recognize_number_letter"
},
{
"Section": "ST_TEXT_LINE_RECOGNITION",
"ImageParameterName": "ip_recognize_number_letter"
}
]
},
{
"Name": "task_recognize_number",
"TextLineSpecificationNameArray": [
"tls_number"
],
"SectionImageParameterArray": [
{
"Section": "ST_REGION_PREDETECTION",
"ImageParameterName": "ip_recognize_textline_number"
},
{
"Section": "ST_TEXT_LINE_LOCALIZATION",
"ImageParameterName": "ip_recognize_textline_number"
},
{
"Section": "ST_TEXT_LINE_RECOGNITION",
"ImageParameterName": "ip_recognize_textline_number"
}
]
},
{
"Name": "task_recognize_letter",
"TextLineSpecificationNameArray": [
"tls_letter"
],
"SectionImageParameterArray": [
{
"Section": "ST_REGION_PREDETECTION",
"ImageParameterName": "ip_recognize_letter"
},
{
"Section": "ST_TEXT_LINE_LOCALIZATION",
"ImageParameterName": "ip_recognize_letter"
},
{
"Section": "ST_TEXT_LINE_RECOGNITION",
"ImageParameterName": "ip_recognize_letter"
}
]
},
{
"Name": "task_recognize_uppercase",
"TextLineSpecificationNameArray": [
"tls_uppercase"
],
"SectionImageParameterArray": [
{
"Section": "ST_REGION_PREDETECTION",
"ImageParameterName": "ip_recognize_uppercase"
},
{
"Section": "ST_TEXT_LINE_LOCALIZATION",
"ImageParameterName": "ip_recognize_uppercase"
},
{
"Section": "ST_TEXT_LINE_RECOGNITION",
"ImageParameterName": "ip_recognize_uppercase"
}
]
},
{
"Name": "task_recognize_number_uppercase",
"TextLineSpecificationNameArray": [
"tls_number_uppercase"
],
"SectionImageParameterArray": [
{
"Section": "ST_REGION_PREDETECTION",
"ImageParameterName": "ip_recognize_number_uppercase"
},
{
"Section": "ST_TEXT_LINE_LOCALIZATION",
"ImageParameterName": "ip_recognize_number_uppercase"
},
{
"Section": "ST_TEXT_LINE_RECOGNITION",
"ImageParameterName": "ip_recognize_number_uppercase"
}
]
},
{
"Name": "task_passport",
"ConfusableCharactersPath": "ConfusableChars.data",
"TextLineSpecificationNameArray": ["tls_mrz_passport"],
"SectionImageParameterArray": [
{
"Section": "ST_REGION_PREDETECTION",
"ImageParameterName": "ip_mrz"
},
{
"Section": "ST_TEXT_LINE_LOCALIZATION",
"ImageParameterName": "ip_mrz"
},
{
"Section": "ST_TEXT_LINE_RECOGNITION",
"ImageParameterName": "ip_mrz"
}
]
},
{
"Name": "task_id",
"ConfusableCharactersPath": "ConfusableChars.data",
"TextLineSpecificationNameArray": ["tls_mrz_id_td1", "tls_mrz_id_td2"],
"SectionImageParameterArray": [
{
"Section": "ST_REGION_PREDETECTION",
"ImageParameterName": "ip_mrz"
},
{
"Section": "ST_TEXT_LINE_LOCALIZATION",
"ImageParameterName": "ip_mrz"
},
{
"Section": "ST_TEXT_LINE_RECOGNITION",
"ImageParameterName": "ip_mrz"
}
]
},
{
"Name": "task_passport_and_id",
"ConfusableCharactersPath": "ConfusableChars.data",
"TextLineSpecificationNameArray": ["tls_mrz_passport", "tls_mrz_id_td1", "tls_mrz_id_td2"],
"SectionImageParameterArray": [
{
"Section": "ST_REGION_PREDETECTION",
"ImageParameterName": "ip_mrz"
},
{
"Section": "ST_TEXT_LINE_LOCALIZATION",
"ImageParameterName": "ip_mrz"
},
{
"Section": "ST_TEXT_LINE_RECOGNITION",
"ImageParameterName": "ip_mrz"
}
]
},
{
"Name": "task_vin_text",
"TextLineSpecificationNameArray": [
"tls_vin_text"
],
"SectionImageParameterArray": [
{
"Section": "ST_REGION_PREDETECTION",
"ImageParameterName": "ip_recognize_vin"
},
{
"Section": "ST_TEXT_LINE_LOCALIZATION",
"ImageParameterName": "ip_recognize_vin"
},
{
"Section": "ST_TEXT_LINE_RECOGNITION",
"ImageParameterName": "ip_recognize_vin"
}
]
}
],
"DocumentNormalizerTaskSettingOptions": [
{
"Name": "task_detect_and_normalize_document",
"SectionImageParameterArray": [
{
"Section": "ST_REGION_PREDETECTION",
"ImageParameterName": "ip_detect_and_normalize"
},
{
"Section": "ST_DOCUMENT_DETECTION",
"ImageParameterName": "ip_detect_and_normalize"
},
{
"Section": "ST_DOCUMENT_NORMALIZATION",
"ImageParameterName": "ip_detect_and_normalize"
}
]
},
{
"Name": "task_detect_document_boundaries",
"TerminateSetting": {
"Section": "ST_DOCUMENT_DETECTION"
},
"SectionImageParameterArray": [
{
"Section": "ST_REGION_PREDETECTION",
"ImageParameterName": "ip_detect"
},
{
"Section": "ST_DOCUMENT_DETECTION",
"ImageParameterName": "ip_detect"
},
{
"Section": "ST_DOCUMENT_NORMALIZATION",
"ImageParameterName": "ip_detect"
}
]
},
{
"Name": "task_normalize_document",
"StartSection": "ST_DOCUMENT_NORMALIZATION",
"SectionImageParameterArray": [
{
"Section": "ST_REGION_PREDETECTION",
"ImageParameterName": "ip_normalize"
},
{
"Section": "ST_DOCUMENT_DETECTION",
"ImageParameterName": "ip_normalize"
},
{
"Section": "ST_DOCUMENT_NORMALIZATION",
"ImageParameterName": "ip_normalize"
}
]
}
],
"ImageParameterOptions": [
{
"Name": "ip_read_barcodes",
"BaseImageParameterName": "ip_read_single_barcode"
},
{
"Name" : "ip_localize_pdf417",
"BinarizationModes" :
[
{
"Mode" : "BM_LOCAL_BLOCK"
}
],
"GrayscaleEnhancementModes" :
[
{
"Mode" : "GEM_GENERAL"
}
]
},
{
"Name" : "ip_decode_pdf417",
"ScaleDownThreshold" : 99999
},
{
"Name": "ip_read_barcodes_speed_first",
"TextDetectionMode": {
"Mode": "TTDM_LINE",
"Direction": "UNKNOWN",
"Sensitivity": 3
},
"IfEraseTextZone": 1,
"BinarizationModes": [
{
"Mode": "BM_LOCAL_BLOCK",
"BlockSizeX": 0,
"BlockSizeY": 0,
"EnableFillBinaryVacancy": 0
}
]
},
{
"Name": "ip_read_barcodes_read_rate",
"TextDetectionMode": {
"Mode": "TTDM_LINE",
"Direction": "UNKNOWN",
"Sensitivity": 3
},
"IfEraseTextZone": 1,
"GrayscaleTransformationModes" : [
{
"Mode": "GTM_ORIGINAL"
},
{
"Mode": "GTM_INVERTED"
}
],
"ScaleDownThreshold" : 100000
},
{
"Name": "ip_read_single_barcode",
"TextDetectionMode": {
"Mode": "TTDM_LINE",
"Direction": "UNKNOWN",
"Sensitivity": 3
},
"IfEraseTextZone": 1,
"BinarizationModes": [
{
"Mode": "BM_LOCAL_BLOCK",
"BlockSizeX": 39,
"BlockSizeY": 39,
"EnableFillBinaryVacancy": 0
}
]
},
{
"Name": "ip_recognize_number_letter",
"TextDetectionMode": {
"Mode": "TTDM_LINE",
"Direction": "HORIZONTAL",
"CharHeightRange": [
20,
1000,
1
],
"Sensitivity": 7
}
},
{
"Name": "ip_recognize_textline_number",
"TextDetectionMode": {
"Mode": "TTDM_LINE",
"Direction": "HORIZONTAL",
"CharHeightRange": [
20,
1000,
1
],
"Sensitivity": 7
}
},
{
"Name": "ip_recognize_letter",
"TextDetectionMode": {
"Mode": "TTDM_LINE",
"Direction": "HORIZONTAL",
"CharHeightRange": [
20,
1000,
1
],
"Sensitivity": 7
}
},
{
"Name": "ip_recognize_uppercase",
"TextDetectionMode": {
"Mode": "TTDM_LINE",
"Direction": "HORIZONTAL",
"CharHeightRange": [
20,
1000,
1
],
"Sensitivity": 7
}
},
{
"Name": "ip_recognize_number_uppercase",
"TextDetectionMode": {
"Mode": "TTDM_LINE",
"Direction": "HORIZONTAL",
"CharHeightRange": [
20,
1000,
1
],
"Sensitivity": 7
}
},
{
"Name": "ip_detect_and_normalize",
"BinarizationModes": [
{
"Mode": "BM_LOCAL_BLOCK",
"BlockSizeX": 0,
"BlockSizeY": 0,
"EnableFillBinaryVacancy": 0
}
],
"TextDetectionMode": {
"Mode": "TTDM_WORD",
"Direction": "HORIZONTAL",
"Sensitivity": 7
}
},
{
"Name": "ip_detect",
"BinarizationModes": [
{
"Mode": "BM_LOCAL_BLOCK",
"BlockSizeX": 0,
"BlockSizeY": 0,
"EnableFillBinaryVacancy": 0
}
],
"TextDetectionMode": {
"Mode": "TTDM_WORD",
"Direction": "HORIZONTAL",
"Sensitivity": 7
}
},
{
"Name": "ip_normalize",
"BinarizationModes": [
{
"Mode": "BM_LOCAL_BLOCK",
"BlockSizeX": 0,
"BlockSizeY": 0,
"EnableFillBinaryVacancy": 0
}
],
"TextDetectionMode": {
"Mode": "TTDM_WORD",
"Direction": "HORIZONTAL",
"Sensitivity": 7
}
},
{
"Name": "ip_mrz",
"TextureDetectionModes": [
{
"Mode": "TDM_GENERAL_WIDTH_CONCENTRATION",
"Sensitivity": 8
}
],
"BinarizationModes": [
{
"EnableFillBinaryVacancy": 0,
"ThresholdCompensation": 21,
"Mode": "BM_LOCAL_BLOCK"
}
],
"TextDetectionMode": {
"Mode": "TTDM_LINE",
"CharHeightRange": [ 5, 1000, 1 ],
"Direction": "HORIZONTAL",
"Sensitivity": 7
}
},
{
"Name" : "ip_localize_vin",
"BinarizationModes" :
[
{
"Mode" : "BM_LOCAL_BLOCK",
"MorphOperation" : "Erode"
}
],
"GrayscaleEnhancementModes" :
[
{
"Mode" : "GEM_GENERAL",
"Sensitivity" : 5,
"SharpenBlockSizeX" : 3,
"SharpenBlockSizeY" : 3,
"SmoothBlockSizeX" : 3,
"SmoothBlockSizeY" : 3
}
],
"GrayscaleTransformationModes" :
[
{
"Mode" : "GTM_ORIGINAL"
},
{
"Mode" : "GTM_INVERTED"
}
]
},
{
"Name" : "ip_decode_vin",
"GrayscaleTransformationModes" :
[
{
"Mode" : "GTM_ORIGINAL"
}
],
"ScaleDownThreshold" : 99999
},
{
"Name": "ip_recognize_vin",
"TextDetectionMode": {
"Mode": "TTDM_LINE",
"Direction": "HORIZONTAL",
"CharHeightRange": [
5,
1000,
1
],
"Sensitivity": 7
},
"GrayscaleTransformationModes": [
{
"Mode": "GTM_ORIGINAL"
},
{
"Mode": "GTM_INVERTED"
}
],
"BinarizationModes" :
[
{
"EnableFillBinaryVacancy" : 1,
"Mode" : "BM_LOCAL_BLOCK"
}
]
}
\s
],
"CharacterModelOptions": [
{
"Name" : "Number"
},
{
"Name" : "Letter"
},
{
"Name" : "Uppercase"
},
{
"Name" : "NumberUppercase"
},
{
"Name" : "NumberLetter"
},
{
"Name": "MRZ"
},
{
"Name": "VIN"
}
],
"SemanticProcessingOptions": [
{
"Name": "sp_passport_and_id",
"ReferenceObjectFilter": {
"ReferenceTargetROIDefNameArray": [
"roi_passport_and_id"
]
},
"TaskSettingNameArray": [
"parse_passport_and_id"
]
},
{
"Name": "sp_passport",
"ReferenceObjectFilter": {
"ReferenceTargetROIDefNameArray": [
"roi_passport"
]
},
"TaskSettingNameArray": [
"parse_passport"
]
},
{
"Name": "sp_id",
"ReferenceObjectFilter": {
"ReferenceTargetROIDefNameArray": [
"roi_id"
]
},
"TaskSettingNameArray": [
"parse_id"
]
},
{
"Name": "sp_pdf_417",
"ReferenceObjectFilter": {
"ReferenceTargetROIDefNameArray": [
"roi_pdf_417"
]
},
"TaskSettingNameArray": [
"parse_pdf_417"
]
},
{
"Name": "sp_vin_barcode",
"ReferenceObjectFilter": {
"ReferenceTargetROIDefNameArray": [
"roi_vin_barcode"
]
},
"TaskSettingNameArray": [
"parse_vin_barcode"
]
},
{
"Name": "sp_vin_text",
"ReferenceObjectFilter": {
"ReferenceTargetROIDefNameArray": [
"roi_vin_text"
]
},
"TaskSettingNameArray": [
"parse_vin_text"
]
}
],
"CodeParserTaskSettingOptions": [
{
"Name": "parse_passport",
"CodeSpecifications": [ "MRTD_TD3_PASSPORT" ]
},
{
"Name": "parse_id",
"CodeSpecifications": [ "MRTD_TD1_ID", "MRTD_TD2_ID" ]
},
{
"Name": "parse_passport_and_id",
"CodeSpecifications": [ "MRTD_TD3_PASSPORT", "MRTD_TD1_ID", "MRTD_TD2_ID" ]
},
{
"Name": "parse_pdf_417",
"CodeSpecifications": ["AAMVA_DL_ID","AAMVA_DL_ID_WITH_MAG_STRIPE","SOUTH_AFRICA_DL"]
},
{
"Name": "parse_vin_barcode",
"CodeSpecifications": ["VIN"]
},
{
"Name": "parse_vin_text",
"CodeSpecifications": ["VIN"]
}
]
}
""";
try {
mRouter.initSettings(template);
} catch (CaptureVisionRouterException e) {
throw new RuntimeException(e);
}
}
We can also update the USB camera’s resolution by changing the PREVIEW_WIDTH and PREVIEW_HEIGHT. OCR requires a higher resolution.
Process Camera Frames Continuously
When a camera is connected, start processing using a timer.
private Timer timer = null;
private void startProcessing(){
TimerTask task = new TimerTask() {
@Override
public void run() {
Bitmap bmp = mUVCCameraView.captureStillImage();
recognize(bmp);
}
};
timer = new Timer();
timer.scheduleAtFixedRate(task, 1000, 100);
}
private void stopProcessing(){
if (timer != null){
timer.cancel();
timer = null;
}
}
private final USBMonitor.OnDeviceConnectListener mOnDeviceConnectListener = new USBMonitor.OnDeviceConnectListener() {
//......
@Override
public void onConnect(final UsbDevice device, final USBMonitor.UsbControlBlock ctrlBlock, final boolean createNew) {
if (mCameraHandler != null) {
mCameraHandler.open(ctrlBlock);
startPreview();
startProcessing(); //newly added
}
}
@Override
public void onDisconnect(final UsbDevice device, final USBMonitor.UsbControlBlock ctrlBlock) {
stopProcessing(); //newly added
}
}
The preview is captured as bitmap for the Dynamsoft SDK to process. The result will be displayed in a TextView.
private void recognize(final Bitmap bitmap){
try {
CapturedResult result = mRouter.capture(bitmap, "ReadPassportAndId"); //recognize MRZ
RecognizedTextLinesResult linesResult = result.getRecognizedTextLinesResult();
runOnUiThread(
new Runnable() {
@Override
public void run() {
if (linesResult != null) {
TextLineResultItem[] results = linesResult.getItems();
StringBuilder linesBuilder = new StringBuilder();
for (TextLineResultItem result : results){
linesBuilder.append(result.getText());
linesBuilder.append("\n");
}
try {
StringBuilder result = new StringBuilder();
ParsedResultItem item = mParser.parse(linesBuilder.toString().getBytes(StandardCharsets.UTF_8),""); //parse MRZ
for (HashMap.Entry<String, String> entry : item.getParsedFields().entrySet()) {
String key = entry.getKey();
String value = entry.getValue();
result.append(key).append(": ").append(value).append("\n");
}
resultTextView.setText(result.toString());
} catch (CodeParserException e) {
resultTextView.setText(e.getMessage());
}
}
}
}
);
} catch (Exception e){
e.printStackTrace();
}
}
Compatibility Notes for Android 9+
On Android 9+, the library may not work if the targetSdkVersion is set larger than 27. You can check out this post to learn more.
Common Issues & Edge Cases
- Camera not recognized after plug-in: The
onAttachcallback fires, butonConnectis not triggered until the user selects the device viaCameraDialog. EnsuremUSBMonitor.register()is called inonStart()and that the USB host feature is declared inAndroidManifest.xml. - Blurry or unreadable MRZ: The default 640×480 resolution is often too low for OCR. Increase
PREVIEW_WIDTHandPREVIEW_HEIGHTto at least 1280×720 for reliable MRZ recognition, especially for TD1-format ID cards. setPreviewSizethrows an exception: Not all USB cameras support every resolution and mode combination. If YUYV mode (PREVIEW_MODE = 0) fails at higher resolutions, switch to MJPEG mode (PREVIEW_MODE = 1), which is more widely supported.
Frequently Asked Questions
How do I scan a passport MRZ using a USB camera on Android?
Connect the USB camera via the Android device’s USB host port, use the UVCCamera library to capture preview frames as Bitmaps, then pass each frame to CaptureVisionRouter.capture(bitmap, "ReadPassportAndId") from Dynamsoft Label Recognizer. The parsed MRZ fields are returned as a ParsedResultItem containing name, nationality, date of birth, and document number.
What resolution does an Android USB camera need for reliable MRZ recognition?
A minimum of 640×480 works for passport TD3 format, but 1280×720 is recommended for TD1 ID cards or when the document is held at distance. Dynamsoft Label Recognizer’s MRZ character model requires at least 30 pixels per character height for reliable recognition.
Why does my UVCCamera preview not work on Android 9 or higher?
The UVCCamera library accesses native USB interfaces that conflict with Android 9+’s stricter enforcement of non-SDK interfaces when targetSdkVersion is above 27. Set targetSdkVersion to 27 or below, or consult the library maintainer’s blog post for available workarounds.