How to Filter and Sort Barcode Results

Dynamsoft Barcode Reader SDK is able to read multiple barcodes at once and return results of all the decoded barcodes. However, you may not want all the results. For example, you may need only the results of a specific barcode format, or you may need only the barcodes with a certain text string. The SDK provides the following parameters to help you filter the barcode results by barcode format, confidence, etc and order the results by confidence, position or format. These parameters can work both individually and in combination.

Available Filter Parameters:

Available Sort Parameter:

Filter by Barcode Angle, Width and Height

You can set the angle, width, and height requirements that the decoded result should meet. Results that do not meet the requirements will be filtered out.

BarcodeAngleRangeArray

Set the angle range that the returned result needs to meet. The value range is [0, 360] (in degrees).

The Angle is defined as the angle between the vector from the lower left corner to the lower right corner of the barcode and the X axis, measured clockwise. Here are some examples:

BarcodeWidthRangeArray

Set the width range that the returned result needs to meet. The value range is [0, 0x7fffffff] (in pixels).

BarcodeHeightRangeArray

Set the height range that the returned result needs to meet. The value range is [0, 0x7fffffff] (in pixels).

Filter by Text Length

Use BarcodeTextLengthRangeArray to set the length range of the decoded text. The value range is [0, 0x7fffffff] (in characters).

Filter by Regular Expression

Use BarcodeTextRegExPattern to specify a regular expression pattern that the decoded text must match. The default value is empty, which means there is no limitation.

For example, if you set BarcodeTextRegExPattern to "[0-9]\d{4,11}", then the result text should be 5 to 12 digits. A result like “123456” matches the expression and will be returned, while “123” (only 3 digits) or “a123456” (contains a letter) will not be returned.

For more information about regular expressions, check out About Regular Expression.

Filter by Confidence Score

The decoding results include a confidence score, and results with too low a score may be incorrect. Use MinResultConfidence to specify the minimum confidence score required for results to be returned. The default value is 30, which is the recommended value for 1D barcodes.

Sort Results with TextResultOrderModes

TextResultOrderModes is used to sort the decoding results. The following modes are available:

Example

Below is an example illustrating how to filter out QR Code results with confidence higher than 50 and then order the results by position.

• Update parameters in your JSON template

    {
        "CaptureVisionTemplates": [
            {
                "Name" : "CV_0",
                "ImageROIProcessingNameArray": ["TA_0" ]
            }       
        ],
        "TargetROIDefOptions" : [
            {
                "Name" : "TA_0",
                "TaskSettingNameArray": [ "BR_0" ]
            }
        ],
        "BarcodeReaderTaskSettingOptions": [
            {
                "Name" : "BR_0",
                "BarcodeFormatIds" : ["BF_QR_CODE"],
                "TextResultOrderModes" : [
                    {
                        "Mode" : "TROM_POSITION"
                    }
                ],
                "BarcodeFormatSpecificationNameArray": "FS_0"
            }
        ],
        "BarcodeFormatSpecificationOptions": [
            {
                "Name" : "FS_0",
                "MinResultConfidence" : 50
            }
        ]
    }
  

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

Advanced Example

Below is a more comprehensive example that demonstrates multiple filter and sort parameters:

{
    "CaptureVisionTemplates": [
        {
            "Name": "CV_0",
            "ImageROIProcessingNameArray": ["TA_0"]
        }
    ],
    "TargetROIDefOptions": [
        {
            "Name": "TA_0",
            "TaskSettingNameArray": ["BR_0"]
        }
    ],
    "BarcodeReaderTaskSettingOptions": [
        {
            "Name": "BR_0",
            "BarcodeFormatIds": ["BF_CODE_39"],
            "TextResultOrderModes": [
                {
                    "Mode": "TROM_CONFIDENCE"
                }
            ],
            "BarcodeFormatSpecificationNameArray": ["FS_0"]
        }
    ],
    "BarcodeFormatSpecificationOptions": [
        {
            "Name": "FS_0",
            "BarcodeAngleRangeArray": [
                {
                    "MinValue": 0,
                    "MaxValue": 90
                }
            ],
            "BarcodeHeightRangeArray": [
                {
                    "MinValue": 0,
                    "MaxValue": 500
                }
            ],
            "BarcodeWidthRangeArray": [
                {
                    "MinValue": 100,
                    "MaxValue": 200
                }
            ],
            "BarcodeTextLengthRangeArray": [
                {
                    "MinValue": 4,
                    "MaxValue": 20
                }
            ],
            "BarcodeTextRegExPattern": "[0-9]{4,}",
            "MinResultConfidence": 30
        }
    ]
}

This template:

• Decodes only CODE_39 barcodes
• Filters results by angle (0-90 degrees), height (0-500 px), width (100-200 px), and text length (4-20 characters)
• Only returns results matching a regular expression (4 or more digits)
• Requires a minimum confidence score of 30
• Orders results by confidence score in descending order