How to Read Barcodes from a Specific Area/Region

Read from a specific region of an image

DBR will locate the code region and decode the entire image by default. However, if only a specific region of the image or video is required to locate the barcode, you can define a Region Of Interest (ROI) via the parameter RegionDefinition. After defining a specific region, DBR will only decode barcodes within that region. Of course, this is very conducive to increasing the speed.

RegionDefinition is the struct that is designed to specify the ROI.

• regionTop: The y coordinate of the Top border of the region.
• regionBottom: The y coordinate of the Bottom border of the region.
• regionLeft: The x coordinate of the left border of the region.
• regionRight: The x coordinate of the right border of the region.
• regionMeasuredByPercentage: If measured by percentage, the above values will be recognized as percentages (1 to 100). Otherwise, the above values will be recognized as pixel length.

Notes:

• You can either configure these settings via the PublicRuntimeSettings struct or via a JSON template.
• When using PublicRuntimeSettings, you can only specify one region.
• When using JSON template, you can specify more than one region.

Single Region Specification

To update the setting via PublicRuntimeSettings:

• Android
• Objective-C
• Swift

// Obtain current runtime settings of `reader` instance.
PublicRuntimeSettings settings = reader.getRuntimeSettings();
settings.region.regionTop = 10;
settings.region.regionBottom = 90;
settings.region.regionLeft = 10;
settings.region.regionRight = 90;
settings.region.regionMeasuredByPercentage = 1;
settings.barcodeFormatIds = EnumBarcodeFormat.BF_QR_CODE | EnumBarcodeFormat.BF_ONED;
// Update the settings.
reader.updateRuntimeSettings(settings);

NSError* err = nil;
// Obtain current runtime settings of `reader` instance.
iPublicRuntimeSettings* settings = [reader getRuntimeSettings:&err];
settings.region.regionTop = 10;
settings.region.regionBottom = 90;
settings.region.regionLeft = 10;
settings.region.regionRight = 90;
settings.region.regionMeasuredByPercentage = 1;
// Update the settings.
[reader updateRuntimeSettings:settings error:&err];

// Obtain current runtime settings of `barcodeReader` instance.
let settings = try? barcodeReader.getRuntimeSettings()
settings?.region.regionTop = 10
settings?.region.regionBottom = 90
settings?.region.regionLeft = 10
settings?.region.regionRight = 90
settings?.region.regionMeasuredByPercentage = 1
// Update the settings.
try? barcodeReader.updateRuntimeSettings(settings!)

To do the same with a JSON Template. Read more on RuntimeSettings and templates:

{ 
   "ImageParameter": {
      "BarcodeFormatIds": ["BF_ALL"],
      "RegionDefinitionNameArray": ["RP_1"]
   }, 
   "RegionDefinition": {
      "Name": "RP_1",
      "Top": 10,
      "Bottom": 90,
      "Left": 10,
      "Right": 90,
      "MeasuredByPercentage": 1,
   },
   "Version": "3.0"
}

Multiple Region Specification

If you need to specify more than one ROI, you have to use a JSON template. Furthermore, you can even configure different barcode-decoding parameter settings for each region. Read more on RuntimeSettings and templates

{
   "ImageParameter": {
      "RegionDefinitionNameArray": ["RP_1", "RP_2"]
   },
   "RegionDefinitionArray": [
      {
         // Settings for ROI 1
         "Name": "RP_1",
         "BarcodeFormatIds": ["BF_CODE_39"],
         "Top": 20,
         "Bottom": 80,
         "Left": 20,
         "Right": 80,
         "ExpectedBarcodesCount": 10,
         "MeasuredByPercentage": 0
      },
      {
         // Settings for ROI 2
         "Name": "RP_2",
         "BarcodeFormatIds": ["BF_CODE_93"],
         "BarcodeFormatIds_2": ["BF_DOTCODE"],
         "Top": 30,
         "Bottom": 70,
         "Left": 30,
         "Right": 80,
         "MeasuredByPercentage": 1
      }
   ],
   "Version": "3.0"
}

Read from a specific region of a video stream

If you are using DBR and DCE to read barcodes from a specific area of the video stream, you can simply define the scan area via DCE.

Note: Dynamsoft Camera Enhancer (DCE) is designed to provide APIs for camera control, camera preview, and other advanced features.

• Android
• Objective-C
• Swift

import com.dynamsoft.dce.CameraEnhancer;
RegionDefinition scanRegion = new RegionDefinition();
scanRegion.regionTop = 30;
scanRegion.regionBottom = 70;
scanRegion.regionRight = 15;
scanRegion.regionLeft = 85;
scanRegion.regionMeasuredByPercentage = 1;
try {
   // mCameraEnhancer is an instance of com.dynamsoft.dce.CameraEnhancer.
   mCameraEnhancer.setScanRegion(scanRegion);
} catch (CameraEnhancerException e) {
   e.printStackTrace();
}

NSError* err = nil;
iRegionDefinition* scanRegion = [[iRegionDefinition alloc] init];
scanRegion.regionTop = 10;
scanRegion.regionBottom = 90;
scanRegion.regionLeft = 10;
scanRegion.regionRight = 90;
scanRegion.regionMeasuredByPercentage = 1;
[dce setScanRegion:scanRegion error:&err];

let scanRegion:iRegionDefinition? = nil
scanRegion?.regionTop = 10
scanRegion?.regionBottom = 90
scanRegion?.regionLeft = 10
scanRegion?.regionRight = 90
scanRegion?.regionMeasuredByPercentage = 1
dce.setScanRegion(region, error:nil)