How to Read High-Density QR Codes

A QR code can store up to 7,089 numbers, 4,296 alphanumeric characters, 2,953 bytes, or 1,817 Japanese Kanjis. As the encoded information increases, the QR code becomes denser. The diagram below displays a QR code that has high density.

High-density QR Code

Figure 1 – High-density QR Code

In some scenarios, high-density QR codes become more difficult to locate and recognize due to small barcode images, perspective, and distortion.

We can do the following to optimize the read rate of high-density QR codes:

Scale up modules if they are too small
Sharpen the image
Run gray equalization

Sample Code

Below is an example illustrating how to configure the parameters to read density QR Codes.

update parameters in your JSON template

  {
      "CaptureVisionTemplates": [
          {
              "Name": "CV_0",
              "ImageROIProcessingNameArray": ["TA_0" ],
              "Timeout":5000
          }       
      ],
      "TargetROIDefOptions" : [
          {
              "Name": "TA_0",
              "TaskSettingNameArray": [ "BR_0" ]
          }
      ],
      "BarcodeReaderTaskSettingOptions": [
          {
              "Name" : "BR_0",
              "BarcodeFormatIds" : ["BF_QR_CODE"],
              "ExpectedBarcodesCount" : 1,
              "SectionImageParameterArray": [
                  {
                      "Section": "ST_REGION_PREDETECTION",
                      "ImageParameterName": "IP_0"
                  },
                  {
                      "Section": "ST_BARCODE_LOCALIZATION",
                      "ImageParameterName": "IP_0"
                  },
                  {
                      "Section": "ST_BARCODE_DECODING",
                      "ImageParameterName": "IP_0"
                  }
              ],
              "LocalizationModes":[
                  {
                      "Mode": "LM_CONNECTED_BLOCKS"
                  }
              ],
              "DeblurModes":[
                  {
                      "Mode": "DM_SHARPENING"
                  },
                  {
                      "Mode": "DM_GRAY_EQUALIZATION"
                  }
              ]
          }
      ],
      "ImageParameterOptions": [
          {
              "Name": "IP_0",
              "ScaleDownThreshold": 10000,
              "ScaleUpModes": [
                  {
                      "Mode": "SUM_LINEAR_INTERPOLATION",
                      "AcuteAngleWithXThreshold": 0,
                      "ModuleSizeThreshold": 4,
                      "TargetModuleSize": 6
                  }
              ]
          }
      ]
  }

apply settings by calling method InitSettingsFromFile

JavaScript
C++
Android
Objective-C
Swift

// `router` is an instance of `CaptureVisionRouter`.
// In the JS edition, the method name we use for initialization is different.
router.initSettings("PATH-TO-YOUR-SETTING")

char szErrorMsg[256] = {0};
CCaptureVisionRouter* cvr = new CCaptureVisionRouter;
cvr->InitSettingsFromFile("PATH-TO-YOUR-SETTING-FILE", szErrorMsg, 256);
// more process here

try {
   // `cvr` is an instance of `CaptureVisionRouter`.
   cvr.initSettingsFromFile("PATH-TO-YOUR-SETTING-FILE");
} catch (CaptureVisionRouterException e) {
   e.printStackTrace();
}

NSError *error;
// `cvr` is an instance of `DSCaptureVisionRouter`.
[self.cvr initSettingsFromFile:@"PATH-TO-YOUR-SETTING-FILE" error:&error];

do{
   //`cvr` is an instance of `CaptureVisionRouter`.
   try cvr.initSettingsFromFile("PATH-TO-YOUR-SETTING-FILE")
}catch{
   // Add code to do when error occurs.
}