Read Inverted Barcodes

Typically, barcodes are dark on a light background. But in some cases, the barcodes are “inverted” – light barcodes on a dark background, as shown in the image below.

Inverted Barcodes

The feature to decode such inverted barcodes is not enabled by default. To control this feature, we must use the GrayscaleTransformationModes. Now for a quick breakdown of each of the modes:

With only GTM_ORIGINAL enabled in GrayscaleTransformationModes, DBR scans only general black-on-white barcodes.
With only GTM_INVERTED enabled in GrayscaleTransformationModes, DBR scans only inverted barcodes.
When GTM_ORIGINAL is enabled as the first mode and GTM_INVERTED is enabled as the second mode in GrayscaleTransformationModes, DBR will try to decode general barcodes first. If the count of decoded barcodes does not reach the expected number, DBR will then try decoding the inverted barcodes.

Example

Below is an example illustrating how to configure the parameter GrayscaleTransformationModes.

Update parameter GrayscaleTransformationModes in your JSON template

  {
      "CaptureVisionTemplates": [
          {
              "Name": "CV_0",
              "ImageROIProcessingNameArray": ["TA_0" ]
          }       
      ],
      "TargetROIDefOptions" : [
          {
              "Name": "TA_0",
              "TaskSettingNameArray": [ "BR_0" ]
          }
      ],
      "BarcodeReaderTaskSettingOptions": [
          {
              "Name" : "BR_0",
              "SectionArray": [
                  {
                      "Section": "ST_REGION_PREDETECTION",
                      "ImageParameterName": "IP_0"
                  },
                  {
                      "Section": "ST_BARCODE_LOCALIZATION",
                      "ImageParameterName": "IP_0"
                  },
                  {
                      "Section": "ST_BARCODE_DECODING",
                      "ImageParameterName": "IP_0"
                  }
              ]
          }
      ],
      "ImageParameterOptions": [
          {
              "Name": "IP_0",
              "ApplicableStages":[
                  { 
                      "Stage": "SST_TRANSFORM_GRAYSCALE",
                      "GrayscaleTransformationModes": [
                          {
                              "Mode": "GTM_ORIGINAL"
                          },
                          {
                              "Mode": "GTM_INVERTED"
                          }
                      ]
          }
      ]
  }

Apply the above settings following the article Use Templates for Configuring Parameters.