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.

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.

To allow for inverted barcodes, add the value GTM_INVERTED to GrayscaleTransformationModes as shown in the code snippet below:

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// Obtains the current runtime settings of DBR.
let settings = await scanner.getRuntimeSettings();
// Adds GTM_INVERTED to grayscaleTransformationModes.
settings.furtherModes.grayscaleTransformationModes = [Dynamsoft.DBR.EnumGrayscaleTransformationMode.GTM_ORIGINAL, Dynamsoft.DBR.EnumGrayscaleTransformationMode.GTM_INVERTED];
// Updates the settings.
await scanner.updateRuntimeSettings(settings);

// Obtain current runtime settings of `reader` instance.
PublicRuntimeSettings settings = reader.getRuntimeSettings();
// Add GTM_INVERTED to GrayscaleTransformationModes to decode inverted barcodes.
settings.furtherModes.grayscaleTransformationModes = new int[]{EnumGrayscaleTransformationMode.GTM_ORIGINAL, EnumGrayscaleTransformationMode.GTM_INVERTED};
// Update the settings.
reader.updateRuntimeSettings(settings);

NSError* err = nil;
// Obtain current runtime settings of `reader` instance.
iPublicRuntimeSettings* settings = [reader getRuntimeSettings:&err];
// Add GTM_INVERTED to GrayscaleTransformationModes to decode inverted barcodes.
settings.furtherModes.grayscaleTransformationModes = @[@(EnumGrayscaleTransformationModeOriginal),@(EnumGrayscaleTransformationModeInverted)];
// Update the settings.
[reader updateRuntimeSettings:settings error:&err];

// Obtain current runtime settings of `barcodeReader` instance.
let settings = try? barcodeReader.getRuntimeSettings()
// Add GTM_INVERTED to GrayscaleTransformationModes to decode inverted barcodes.
settings?.furtherModes.grayscaleTransformationModes = [EnumGrayscaleTransformationMode.original, EnumGrayscaleTransformationMode.inverted]
// Update the settings.
try? barcodeReader.updateRuntimeSettings(settings!)

PublicRuntimeSettings settings;
char szErrorMsg[256] = {0};
// Obtain current runtime settings of `reader` instance.
DBR_GetRuntimeSettings(reader, &settings);
// Add GTM_INVERTED to GrayscaleTransformationModes to decode inverted barcodes.
settings.furtherModes.grayscaleTransformationModes[0] = GTM_ORIGINAL;
settings.furtherModes.grayscaleTransformationModes[1] = GTM_INVERTED;
// Update the settings.
DBR_UpdateRuntimeSettings(reader, &settings, szErrorMsg, 256);

PublicRuntimeSettings settings;
char szErrorMsg[256] = {0};
// Obtain current runtime settings of `reader` instance.
reader.GetRuntimeSettings(&settings);
// Add GTM_INVERTED to GrayscaleTransformationModes to decode inverted barcodes.
settings.furtherModes.grayscaleTransformationModes[0] = GTM_ORIGINAL;
settings.furtherModes.grayscaleTransformationModes[1] = GTM_INVERTED;
// Update the settings.
reader.UpdateRuntimeSettings(&settings, szErrorMsg, 256);

// Obtain current runtime settings of `reader` instance.
PublicRuntimeSettings settings = reader.GetRuntimeSettings();
// Add GTM_INVERTED to GrayscaleTransformationModes to decode inverted barcodes.
settings.FurtherModes.GrayscaleTransformationModes[0] = GTM_ORIGINAL;
settings.FurtherModes.GrayscaleTransformationModes[1] = GTM_INVERTED;
// Update the settings.
reader.UpdateRuntimeSettings(settings);

// Obtain current runtime settings of `reader` instance.
PublicRuntimeSettings settings = reader.getRuntimeSettings();
// Add GTM_INVERTED to GrayscaleTransformationModes to decode inverted barcodes.
settings.furtherModes.grayscaleTransformationModes = new int[]{EnumGrayscaleTransformationMode.GTM_ORIGINAL, EnumGrayscaleTransformationMode.GTM_INVERTED};
// Update the settings.
reader.updateRuntimeSettings(settings);

# Obtain current runtime settings of `reader` instance.
settings = reader.get_runtime_settings()
# Add GTM_INVERTED to GrayscaleTransformationModes to decode inverted barcodes.
settings.grayscale_transformation_modes[0] = EnumGrayscaleTransformationMode.GTM_ORIGINAL
settings.grayscale_transformation_modes[1] = EnumGrayscaleTransformationMode.GTM_INVERTED
# Update the settings.
reader.update_runtime_settings(settings)