IMAQ Read Barcode Doesn't Find My Barcode

Updated Mar 21, 2019

Reported In

Software

  • Vision Development Module
  • LabVIEW

Issue Details

I've changed the standard Vision Read 1D Barcode.vi example (from Help >> Find Examples... >> Toolkits and Modules >> Vision >> Barcodes) by adding vision acquisition from a webcam in order to find and recognize barcodes on the fly. But Read 1D Barcode.vi returns no barcodes from a live image or ead Data is incorrectly in the most of the time., however it reads barcodes perfectly from vision example offline images.

Are there any recommendations on how to improve the original image in order to locate and recognize barcodes correctly?

Solution

The following factors can cause errors in the decoding process:
  • Very low resolution of the image
  • Very high horizontal or vertical light drift
  • Contrast along the bars of the image
  • High level of noise

So the first step is to try to improve quality of the acquired image in the following ways:
  • An acquired image has enough luminance for a processing
    • An exposure time of a camera can be increased
    • A light source can be added
  • Make sure that a barcode is in a focus and is not blurred
  • Check if a barcode itself has an adequate size to be recognized
    • A barcode can be placed closer to a camera
    • A resolution of a camera can be increased

Additional Information

It is recommended to specify ROI in the image which helps localize the region occupied by the Barcode. It is optional, but it can increase the performance of the processing by reducing the size of the search region.

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