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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.
}

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